Backbone amide linker (BAL) strategy for solid-phase synthesis of C- terminal-modified and cyclic peptides

Journal of the American Chemical Society

Volumn 120, Issue 22, 1998, Pages 5441-5452

  Jensen, Knud J ^a,c   Alsina, Jordi ^a,b   Songster, Michael F ^a,d   Vágner, Josef ^a,e   Albericio, Fernando ^a,b   Barany, George ^a  

^a UNIVERSITY OF MINNESOTA   (United States)

^b UNIVERSITY OF BARCELONA   (Spain)

^c TECHNICAL UNIVERSITY OF DENMARK   (Denmark)

^d Solid Phase Sciences

^e NOVO NORDISK A S   (Denmark)

Author keywords

[No Author keywords available]

Indexed keywords

CYCLOPEPTIDE;

ACYLATION; ARTICLE; CARBOXY TERMINAL SEQUENCE; HIGH PERFORMANCE LIQUID CHROMATOGRAPHY; PEPTIDE SYNTHESIS; REACTION ANALYSIS;

EID: 0032503569     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja974116f     Document Type: Article

References (104)

1. Taken in part from the Ph.D. theses of M.F.S. (University of Minnesota, July, 1996) and J.A. (University of Barcelona, October, 1997).
2. Portions of this work were reported in preliminary form: (a) Jensen, K. J.; Songster, M. F.; Vágner, J.; Alsina, J.; Albericio, F.; Barany, G. In Peptides - Chemistry, Structure and Biology: Proceedings of the Fourteenth American Peptide Symposium, Columbus, OH, June 18-23, 1995; Kaumaya, P. T. P., Hodges, R. S., Eds.; Mayflower Scientific: Kingswinford, U.K., 1996; pp 30-32. (b) Jensen, K. J.; Songster, M. F.; Vágner, J.; Alsina, J.; Albericio, F.; Barany, G. In Innovation and Perspectives in Solid Phase Synthesis & Combinatorial Libraries, 1996, Collected Papers, Fourth International Symposium, Edinburgh, Scotland, September 12-16, 1995; Epton, R., Ed.; Mayflower Scientific: Kingswinford, U.K., 1997; pp 187-190.
3. Portions of this work were reported in preliminary form: (a) Jensen, K. J.; Songster, M. F.; Vágner, J.; Alsina, J.; Albericio, F.; Barany, G. In Peptides - Chemistry, Structure and Biology: Proceedings of the Fourteenth American Peptide Symposium, Columbus, OH, June 18-23, 1995; Kaumaya, P. T. P., Hodges, R. S., Eds.; Mayflower Scientific: Kingswinford, U.K., 1996; pp 30-32. (b) Jensen, K. J.; Songster, M. F.; Vágner, J.; Alsina, J.; Albericio, F.; Barany, G. In Innovation and Perspectives in Solid Phase Synthesis & Combinatorial Libraries, 1996, Collected Papers, Fourth International Symposium, Edinburgh, Scotland, September 12-16, 1995; Epton, R., Ed.; Mayflower Scientific: Kingswinford, U.K., 1997; pp 187-190.
4. After our preliminary reports on BAL (ref 2), we became aware of two conceptually related handles, neither of which was exploited to its full potential: (a) Rivier, J.; Porter, J.; Hoeger, C. In Peptides: Chemistry, Biology, Interactions with Proteins; Penke, B., Török, A., Eds.; Walter de Gruyter. Berlin, 1988; pp 75-78. (b) Renil, M.; Pillai, V. N. R. Tetrahedron Lett. 1994, 35, 3809-3812. In addition, the aldehyde precursor to PAL was subjected to reductive amination with amino acid methyl esters to achieve a linkage akin to BAL, in work that was submitted later than our disclosures: (c) Boojamra, C. G.; Burow, K. M.; Ellman, J. A. J. Org. Chem. 1995, 60, 5742-5743. (d) Boojamra, C. G.; Burow, K. M.; Thompson, L. A.; Ellman, J. A. J. Org. Chem. 1997, 62, 1240-1256. Finally, BAL chemistry is implicit in the anchoring of modified purines through an aniline side chain, as reported by (e) Gray, N. S.; Kwon, S.; Schultz, P. G. Tetrahedron Lett. 1997, 38, 1161-1164, and in the anchoring of O-protected hydroxylamines to access hydroxamates, see (f) Ngu, K.; Patel, D. V. J. Org. Chem. 1997, 62, 7088-7089.
5. After our preliminary reports on BAL (ref 2), we became aware of two conceptually related handles, neither of which was exploited to its full potential: (a) Rivier, J.; Porter, J.; Hoeger, C. In Peptides: Chemistry, Biology, Interactions with Proteins; Penke, B., Török, A., Eds.; Walter de Gruyter. Berlin, 1988; pp 75-78. (b) Renil, M.; Pillai, V. N. R. Tetrahedron Lett. 1994, 35, 3809-3812. In addition, the aldehyde precursor to PAL was subjected to reductive amination with amino acid methyl esters to achieve a linkage akin to BAL, in work that was submitted later than our disclosures: (c) Boojamra, C. G.; Burow, K. M.; Ellman, J. A. J. Org. Chem. 1995, 60, 5742-5743. (d) Boojamra, C. G.; Burow, K. M.; Thompson, L. A.; Ellman, J. A. J. Org. Chem. 1997, 62, 1240-1256. Finally, BAL chemistry is implicit in the anchoring of modified purines through an aniline side chain, as reported by (e) Gray, N. S.; Kwon, S.; Schultz, P. G. Tetrahedron Lett. 1997, 38, 1161-1164, and in the anchoring of O-protected hydroxylamines to access hydroxamates, see (f) Ngu, K.; Patel, D. V. J. Org. Chem. 1997, 62, 7088-7089.
6. After our preliminary reports on BAL (ref 2), we became aware of two conceptually related handles, neither of which was exploited to its full potential: (a) Rivier, J.; Porter, J.; Hoeger, C. In Peptides: Chemistry, Biology, Interactions with Proteins; Penke, B., Török, A., Eds.; Walter de Gruyter. Berlin, 1988; pp 75-78. (b) Renil, M.; Pillai, V. N. R. Tetrahedron Lett. 1994, 35, 3809-3812. In addition, the aldehyde precursor to PAL was subjected to reductive amination with amino acid methyl esters to achieve a linkage akin to BAL, in work that was submitted later than our disclosures: (c) Boojamra, C. G.; Burow, K. M.; Ellman, J. A. J. Org. Chem. 1995, 60, 5742-5743. (d) Boojamra, C. G.; Burow, K. M.; Thompson, L. A.; Ellman, J. A. J. Org. Chem. 1997, 62, 1240-1256. Finally, BAL chemistry is implicit in the anchoring of modified purines through an aniline side chain, as reported by (e) Gray, N. S.; Kwon, S.; Schultz, P. G. Tetrahedron Lett. 1997, 38, 1161-1164, and in the anchoring of O-protected hydroxylamines to access hydroxamates, see (f) Ngu, K.; Patel, D. V. J. Org. Chem. 1997, 62, 7088-7089.
7. After our preliminary reports on BAL (ref 2), we became aware of two conceptually related handles, neither of which was exploited to its full potential: (a) Rivier, J.; Porter, J.; Hoeger, C. In Peptides: Chemistry, Biology, Interactions with Proteins; Penke, B., Török, A., Eds.; Walter de Gruyter. Berlin, 1988; pp 75-78. (b) Renil, M.; Pillai, V. N. R. Tetrahedron Lett. 1994, 35, 3809-3812. In addition, the aldehyde precursor to PAL was subjected to reductive amination with amino acid methyl esters to achieve a linkage akin to BAL, in work that was submitted later than our disclosures: (c) Boojamra, C. G.; Burow, K. M.; Ellman, J. A. J. Org. Chem. 1995, 60, 5742-5743. (d) Boojamra, C. G.; Burow, K. M.; Thompson, L. A.; Ellman, J. A. J. Org. Chem. 1997, 62, 1240-1256. Finally, BAL chemistry is implicit in the anchoring of modified purines through an aniline side chain, as reported by (e) Gray, N. S.; Kwon, S.; Schultz, P. G. Tetrahedron Lett. 1997, 38, 1161-1164, and in the anchoring of O-protected hydroxylamines to access hydroxamates, see (f) Ngu, K.; Patel, D. V. J. Org. Chem. 1997, 62, 7088-7089.
8. After our preliminary reports on BAL (ref 2), we became aware of two conceptually related handles, neither of which was exploited to its full potential: (a) Rivier, J.; Porter, J.; Hoeger, C. In Peptides: Chemistry, Biology, Interactions with Proteins; Penke, B., Török, A., Eds.; Walter de Gruyter. Berlin, 1988; pp 75-78. (b) Renil, M.; Pillai, V. N. R. Tetrahedron Lett. 1994, 35, 3809-3812. In addition, the aldehyde precursor to PAL was subjected to reductive amination with amino acid methyl esters to achieve a linkage akin to BAL, in work that was submitted later than our disclosures: (c) Boojamra, C. G.; Burow, K. M.; Ellman, J. A. J. Org. Chem. 1995, 60, 5742-5743. (d) Boojamra, C. G.; Burow, K. M.; Thompson, L. A.; Ellman, J. A. J. Org. Chem. 1997, 62, 1240-1256. Finally, BAL chemistry is implicit in the anchoring of modified purines through an aniline side chain, as reported by (e) Gray, N. S.; Kwon, S.; Schultz, P. G. Tetrahedron Lett. 1997, 38, 1161-1164, and in the anchoring of O-protected hydroxylamines to access hydroxamates, see (f) Ngu, K.; Patel, D. V. J. Org. Chem. 1997, 62, 7088-7089.
9. After our preliminary reports on BAL (ref 2), we became aware of two conceptually related handles, neither of which was exploited to its full potential: (a) Rivier, J.; Porter, J.; Hoeger, C. In Peptides: Chemistry, Biology, Interactions with Proteins; Penke, B., Török, A., Eds.; Walter de Gruyter. Berlin, 1988; pp 75-78. (b) Renil, M.; Pillai, V. N. R. Tetrahedron Lett. 1994, 35, 3809-3812. In addition, the aldehyde precursor to PAL was subjected to reductive amination with amino acid methyl esters to achieve a linkage akin to BAL, in work that was submitted later than our disclosures: (c) Boojamra, C. G.; Burow, K. M.; Ellman, J. A. J. Org. Chem. 1995, 60, 5742-5743. (d) Boojamra, C. G.; Burow, K. M.; Thompson, L. A.; Ellman, J. A. J. Org. Chem. 1997, 62, 1240-1256. Finally, BAL chemistry is implicit in the anchoring of modified purines through an aniline side chain, as reported by (e) Gray, N. S.; Kwon, S.; Schultz, P. G. Tetrahedron Lett. 1997, 38, 1161-1164, and in the anchoring of O-protected hydroxylamines to access hydroxamates, see (f) Ngu, K.; Patel, D. V. J. Org. Chem. 1997, 62, 7088-7089.
10. Review: Songster, M. F.; Barany, G. Methods Enzymol. 1997, 259, 126-174.
11. Reviews: (a) Ovchinnikov, Y. A.; Ivanov, V. T. In The Proteins; Neurath, H., Hill, R. L., Eds.; Academic: New York, 1982; pp 307-642. (b) Rizo, J.; Gierasch, L. M. Annu. Rev. Biochem. 1992, 61, 387-418. (c) Kates, S. A.; Solé, N. A.; Albericio, F.; Barany, G. In Peptides: Design, Synthesis, and Biological Activity; Basava, C., Anantharamaiah, G. M., Eds.; Birkhäuser: Boston, MA, 1994; pp 39-58.
12. Reviews: (a) Ovchinnikov, Y. A.; Ivanov, V. T. In The Proteins; Neurath, H., Hill, R. L., Eds.; Academic: New York, 1982; pp 307-642. (b) Rizo, J.; Gierasch, L. M. Annu. Rev. Biochem. 1992, 61, 387-418. (c) Kates, S. A.; Solé, N. A.; Albericio, F.; Barany, G. In Peptides: Design, Synthesis, and Biological Activity; Basava, C., Anantharamaiah, G. M., Eds.; Birkhäuser: Boston, MA, 1994; pp 39-58.
13. Reviews: (a) Ovchinnikov, Y. A.; Ivanov, V. T. In The Proteins; Neurath, H., Hill, R. L., Eds.; Academic: New York, 1982; pp 307-642. (b) Rizo, J.; Gierasch, L. M. Annu. Rev. Biochem. 1992, 61, 387-418. (c) Kates, S. A.; Solé, N. A.; Albericio, F.; Barany, G. In Peptides: Design, Synthesis, and Biological Activity; Basava, C., Anantharamaiah, G. M., Eds.; Birkhäuser: Boston, MA, 1994; pp 39-58.
14. For reviews describing convergent approaches for syntheses of longer peptides, see: (a) Barany, G.; Merrifield, R. B. In The Peptides; Gross, E., Meienhofer, J., Eds.; Academic: New York, 1979; Vol. 2, pp 1-284. (b) Lloyd-Williams, P.; Albericio, F.; Giralt, E. Tetrahedron 1993, 49, 11065-11133. (c) Benz, H. Synthesis 1994, 337-358. (d) Albericio, F.; Lloyd-Williams, P.; Giralt, E. Methods Enzymol. 1997, 289, 313-336.
15. For reviews describing convergent approaches for syntheses of longer peptides, see: (a) Barany, G.; Merrifield, R. B. In The Peptides; Gross, E., Meienhofer, J., Eds.; Academic: New York, 1979; Vol. 2, pp 1-284. (b) Lloyd-Williams, P.; Albericio, F.; Giralt, E. Tetrahedron 1993, 49, 11065-11133. (c) Benz, H. Synthesis 1994, 337-358. (d) Albericio, F.; Lloyd-Williams, P.; Giralt, E. Methods Enzymol. 1997, 289, 313-336.
16. For reviews describing convergent approaches for syntheses of longer peptides, see: (a) Barany, G.; Merrifield, R. B. In The Peptides; Gross, E., Meienhofer, J., Eds.; Academic: New York, 1979; Vol. 2, pp 1-284. (b) Lloyd-Williams, P.; Albericio, F.; Giralt, E. Tetrahedron 1993, 49, 11065-11133. (c) Benz, H. Synthesis 1994, 337-358. (d) Albericio, F.; Lloyd-Williams, P.; Giralt, E. Methods Enzymol. 1997, 289, 313-336.
17. For reviews describing convergent approaches for syntheses of longer peptides, see: (a) Barany, G.; Merrifield, R. B. In The Peptides; Gross, E., Meienhofer, J., Eds.; Academic: New York, 1979; Vol. 2, pp 1-284. (b) Lloyd-Williams, P.; Albericio, F.; Giralt, E. Tetrahedron 1993, 49, 11065-11133. (c) Benz, H. Synthesis 1994, 337-358. (d) Albericio, F.; Lloyd-Williams, P.; Giralt, E. Methods Enzymol. 1997, 289, 313-336.
18. The use of C-terminal-modified peptides in convergent syntheses has been covered in several further reviews, see: (a) Lloyd-Williams, P.; Albericio, F.; Giralt, E. Chemical Approaches to the Synthesis of Peptides and Proteins; CRC: Boca Raton, FL, 1997. (b) Muir, T. W.; Dawson, P. E.; Kent, S. B. H. Methods Enzymol. 1997, 289, 266-298. (c) Tam, J. P.; Spetzler, J. C. Methods Enzymol. 1997, 289, 612-637.
19. The use of C-terminal-modified peptides in convergent syntheses has been covered in several further reviews, see: (a) Lloyd-Williams, P.; Albericio, F.; Giralt, E. Chemical Approaches to the Synthesis of Peptides and Proteins; CRC: Boca Raton, FL, 1997. (b) Muir, T. W.; Dawson, P. E.; Kent, S. B. H. Methods Enzymol. 1997, 289, 266-298. (c) Tam, J. P.; Spetzler, J. C. Methods Enzymol. 1997, 289, 612-637.
20. The use of C-terminal-modified peptides in convergent syntheses has been covered in several further reviews, see: (a) Lloyd-Williams, P.; Albericio, F.; Giralt, E. Chemical Approaches to the Synthesis of Peptides and Proteins; CRC: Boca Raton, FL, 1997. (b) Muir, T. W.; Dawson, P. E.; Kent, S. B. H. Methods Enzymol. 1997, 289, 266-298. (c) Tam, J. P.; Spetzler, J. C. Methods Enzymol. 1997, 289, 612-637.
21. (a) Stewart, J. M.; Young, J. D. Solid-Phase Peptide Synthesis, 2nd ed.; Pierce Chemical: Rockford, IL, 1984.
22. (b) Merrifield, R. B. Science 1986, 232, 341-347.
23. (c) Barany, G.; Kneib-Cordonier, N.; Mullen, D. G. Int. J. Pept. Protein Res. 1987, 30, 705-739.
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25. (e) Fields, G. B.; Tian, Z.; Barany, G. In Synthetic Peptides: A User's Guide; Grant, G. A., Ed.; W. H. Freeman: New York, 1992; pp 259-345.
26. Handles are defined as bifunctional spacers which serve to attach the initial residue to the polymeric support in two discrete steps. One end of the handle incorporates features of a smoothly cleavable protecting group, and the other end allows facile coupling to a previously functionalized support. For reviews and extensive tabulations of handles, see refs 6, 8, and 10c,e.
27. (a) Albericio, F.; Barany, G. Int. J. Pept. Protein Res. 1987, 30, 206-216.
28. (b) Albericio, F.; Kneib-Cordonier, N.; Biancalana, S.; Gera, L.; Masada, R. I.; Hudson, D.; Barany, G. J. Org. Chem. 1990, 55, 3730-3743.
29. (c) Sharma, S. K.; Songster, M. F.; Colpitts, T. L.; Hegyes, P.; Barany, G.; Castellino, F. J. J. Org. Chem. 1993, 58, 4993-4996.
30. (d) Songster, M. F.; Vágner, J.; Barany, G. Lett. Pept. Sci. 1996, 2, 265-270.
31. (a) Breipohl, G.; Knolle, J.; Stüber, W. Int. J. Pepl. Protein Res. 1990, 55, 281-283.
32. (b) Albericio, F.; Van Abel, R.; Barany, G. Int. J. Pept. Protein Res. 1990, 35, 284-286.
33. (c) Trzeciak, A.; Bannwarth, W. Tetrahedron Lett. 1992, 33, 4557-4560.
34. (d) Kates, S. A.; Sole, N. A.; Johnson, C. R.; Hudson, D.; Barany, G.; Albericio, F. Tetrahedron Lett. 1993, 34, 1549-1552.
35. (e) Lee, J.; Griffin, J. H.; Nicas, T. I. J. Org. Chem. 1996, 61, 3983-3986.
36. (f) Alsina, J.; Chiva, C.; Ortiz, M.; Rabanal, F.; Giralt, E.; Albericio, F. Tetrahedron Lett. 1997, 38, 883-886.
37. (a) Weygand, F.; Steglich, W.; Bjarnason, J. Tetrahedron Lett. 1966, 3483-3487.
38. (b) Narita, M.; Fukunaga, T.; Wakabayashi, A.; Ishikawa, K.; Nakano, H. Int. J. Pept. Protein Res. 1984, 23, 306-314.
39. (c) Blaakmeer, J.; Tijsse-Klasen, T.; Tesser, G. I. Int. J. Pept. Protein Res. 1991, 37, 556-564.
40. (d) Johnson, T.; Quibell, M.; Sheppard, R. C. J. Pept. Sci. 1995, 1, 11-25.
41. (e) Quibell, M.; Packman, L. C.; Johnson, T. J. Am. Chem. Soc. 1995, 117, 11656-11668.
42. (f) Simmonds, R. G. Int. J. Pept. Protein Res. 1996, 47, 36-41.
43. (g) Clausen, N.; Goldammer, C.; Jauch, K.; Bayer, E. In Peptides - Chemistry, Structure and Biology: Proceedings of the Fourteenth American Peptide Symposium; Kaumaya, P. T. P., Hodges, R. S., Eds.; Mayflower Scientific: Kingswinford, U.K., 1996; pp 71-72.
44. (h) Nicolás, E.; Pujades, M.; Bacardit, J.; Giralt, E.; Albericio, F. Tetrahedron Lett. 1997, 38, 2317-2320.
45. For all structural formulas in this paper, PALdehyde and BAL handles are depicted as the isomer in which the aminomethyl group is para to the valeryl linking group (refs 12b,d). Some experiments described herein started instead with a mixture (1:2) of the ortho and para isomers of PALdehyde, i.e. o,p-PALdehyde (refs 12a-c); furthermore, the side-chain moiety had one fewer carbon (substitution of butyryl for valeryl). The latter compound is commercially available from the BioSearch division of PerSeptive Biosystems (Framingham, MA).
46. Similar results were obtained using as solvent HOAc-MeOH (1:100), MeOH-THF (1:4), or allyl alcohol. Reaction was incomplete in iPrOH, while in DMF (neat) or HOAc-DMF (1:100), the desired secondary amines (3) were sometimes minor while the major products were the di-BAL-kylated tertiary amines, apparently formed by addition of a second equiv of 2 (see ref 12c for precedents).
47. (a) Barany, G.; Albericio, F.; Sole, N. A.; Griffin, G. W.; Kates, S. A.; Hudson, D. In Peptides 1992: Proceedings of the Twenty-Second European Peptide Symposium; Schneider, C. H., Eberle, A. N., Eds.; ESCOM Science Publishers: Leiden, The Netherlands, 1993; pp 267-268.
48. (b) Zalipsky, S.; Chang, J. L.; Albericio, F.; Barany, G. React. Polym. 1994, 22, 243-258.
49. (c) Barany, G.; Albericio, F.; Kates, S. A.; Kempe, M. In Chemistry and Biological Application of Polyethylene Glycol; ACS Symposium Series 680; Harris, J. M., Zalipsky, S., Eds.; American Chemical Society Books: Washington, DC, 1997; pp 239-264.
50. Sasaki, Y.; Coy, D. H. Peptides 1987, 8, 119-121.
51. Solvents of choice were DMF, as reported by Sasaki and Coy in ref 18, or MeOH, as suggested by solution precedents (this work, covered previously). Given the tendency for dialkylation in solution with DMF as solvent (see footnote 16), the relative absence of such an unfavorable side reaction in the solid-phase case is taken as evidence for relative site isolation, as has been covered in numerous review articles (e.g., ref 8a). The success of on-resin monoreductive amination in DMF is also attributable to the considerable excess of amine, later removed readily by filtration and washing, that can be used in the reaction. In the solution case, use of excess amine leads to complications in the workup and purification of the Fmoc-protected preformed handle 1.
52. (a) Atherton, E.; Clive, D. L.; Sheppard, R. C. J. Am. Chem. Soc. 1975, 97, 6584-6585.
53. (b) Matsueda, G. R.; Haber, E. Anal. Biochem. 1980, 104, 215-227.
54. (c) Albericio, F.; Barany, G. Int. J. Pept. Protein Res. 1993, 41, 307-312.
55. The development and applications of the revelant coupling reagents are reported by the following: (a) Castro, B.; Dormoy, J. R.; Evin, G.; Selve, C. Tetrahedron Lett. 1975, 1219-1222. (b) Dourtoglou, V.; Ziegler, J.-C; Gross, B. Tetrahedron Lett. 1978, 1269-1272. (c) Fournier, A.; Wang, C. T.; Felix, A. M. Int. J. Pept. Protein Res. 1988, 31, 86-97. (d) Hudson, D. J. Org. Chem. 1988, 53, 617-624. (e) Knorr, R.; Trzeciak, A.; Bannwarth, W.; Gillessen, D. Tetrahedron Lett. 1989, 30, 1219-1222. (f) Frérot, E.; Coste, J.; Pantaloni, A.; Dufour, M.-N.; Jouin, P. Tetrahedron 1991, 47, 259-270. (g) Carpino, L. A. J. Am. Chem. Soc. 1993, 115, 4397-4398. (h) Carpino, L. A.; El-Faham, A.; Minor, C. A.; Albericio, F. J. Chem. Soc., Chem. Commun. 1994, 201-203. (i) Kates, S. A.; Minor, C. A.; Shroff, H.; Haaseth, R. C.; Triolo, S.; El-Faham, A.; Carpino, L. A.; Albericio, F. In Peptides 1994: Proceedings of the Twenty-Third European Peptide Symposium; Maia, H. L. S., Ed.; ESCOM: Leiden, The Netherlands, 1995; pp 248-249. (j) Carpino, L. A.; El-Faham, A. J. Am. Chem. Soc. 1995, 117, 5401-5402. (k) Carpino, L. A.; Beyermann, M.; Wenschuh, H.; Bienert, M. Acc. Chem. Res. 1996, 29, 268-274. (l) Albericio, F.; Carpino, L. A. Methods Enzymol. 1997, 289, 104-126.
56. The development and applications of the revelant coupling reagents are reported by the following: (a) Castro, B.; Dormoy, J. R.; Evin, G.; Selve, C. Tetrahedron Lett. 1975, 1219-1222. (b) Dourtoglou, V.; Ziegler, J.-C; Gross, B. Tetrahedron Lett. 1978, 1269-1272. (c) Fournier, A.; Wang, C. T.; Felix, A. M. Int. J. Pept. Protein Res. 1988, 31, 86-97. (d) Hudson, D. J. Org. Chem. 1988, 53, 617-624. (e) Knorr, R.; Trzeciak, A.; Bannwarth, W.; Gillessen, D. Tetrahedron Lett. 1989, 30, 1219-1222. (f) Frérot, E.; Coste, J.; Pantaloni, A.; Dufour, M.-N.; Jouin, P. Tetrahedron 1991, 47, 259-270. (g) Carpino, L. A. J. Am. Chem. Soc. 1993, 115, 4397-4398. (h) Carpino, L. A.; El-Faham, A.; Minor, C. A.; Albericio, F. J. Chem. Soc., Chem. Commun. 1994, 201-203. (i) Kates, S. A.; Minor, C. A.; Shroff, H.; Haaseth, R. C.; Triolo, S.; El-Faham, A.; Carpino, L. A.; Albericio, F. In Peptides 1994: Proceedings of the Twenty-Third European Peptide Symposium; Maia, H. L. S., Ed.; ESCOM: Leiden, The Netherlands, 1995; pp 248-249. (j) Carpino, L. A.; El-Faham, A. J. Am. Chem. Soc. 1995, 117, 5401-5402. (k) Carpino, L. A.; Beyermann, M.; Wenschuh, H.; Bienert, M. Acc. Chem. Res. 1996, 29, 268-274. (l) Albericio, F.; Carpino, L. A. Methods Enzymol. 1997, 289, 104-126.
57. The development and applications of the revelant coupling reagents are reported by the following: (a) Castro, B.; Dormoy, J. R.; Evin, G.; Selve, C. Tetrahedron Lett. 1975, 1219-1222. (b) Dourtoglou, V.; Ziegler, J.-C; Gross, B. Tetrahedron Lett. 1978, 1269-1272. (c) Fournier, A.; Wang, C. T.; Felix, A. M. Int. J. Pept. Protein Res. 1988, 31, 86-97. (d) Hudson, D. J. Org. Chem. 1988, 53, 617-624. (e) Knorr, R.; Trzeciak, A.; Bannwarth, W.; Gillessen, D. Tetrahedron Lett. 1989, 30, 1219-1222. (f) Frérot, E.; Coste, J.; Pantaloni, A.; Dufour, M.-N.; Jouin, P. Tetrahedron 1991, 47, 259-270. (g) Carpino, L. A. J. Am. Chem. Soc. 1993, 115, 4397-4398. (h) Carpino, L. A.; El-Faham, A.; Minor, C. A.; Albericio, F. J. Chem. Soc., Chem. Commun. 1994, 201-203. (i) Kates, S. A.; Minor, C. A.; Shroff, H.; Haaseth, R. C.; Triolo, S.; El-Faham, A.; Carpino, L. A.; Albericio, F. In Peptides 1994: Proceedings of the Twenty-Third European Peptide Symposium; Maia, H. L. S., Ed.; ESCOM: Leiden, The Netherlands, 1995; pp 248-249. (j) Carpino, L. A.; El-Faham, A. J. Am. Chem. Soc. 1995, 117, 5401-5402. (k) Carpino, L. A.; Beyermann, M.; Wenschuh, H.; Bienert, M. Acc. Chem. Res. 1996, 29, 268-274. (l) Albericio, F.; Carpino, L. A. Methods Enzymol. 1997, 289, 104-126.
58. The development and applications of the revelant coupling reagents are reported by the following: (a) Castro, B.; Dormoy, J. R.; Evin, G.; Selve, C. Tetrahedron Lett. 1975, 1219-1222. (b) Dourtoglou, V.; Ziegler, J.-C; Gross, B. Tetrahedron Lett. 1978, 1269-1272. (c) Fournier, A.; Wang, C. T.; Felix, A. M. Int. J. Pept. Protein Res. 1988, 31, 86-97. (d) Hudson, D. J. Org. Chem. 1988, 53, 617-624. (e) Knorr, R.; Trzeciak, A.; Bannwarth, W.; Gillessen, D. Tetrahedron Lett. 1989, 30, 1219-1222. (f) Frérot, E.; Coste, J.; Pantaloni, A.; Dufour, M.-N.; Jouin, P. Tetrahedron 1991, 47, 259-270. (g) Carpino, L. A. J. Am. Chem. Soc. 1993, 115, 4397-4398. (h) Carpino, L. A.; El-Faham, A.; Minor, C. A.; Albericio, F. J. Chem. Soc., Chem. Commun. 1994, 201-203. (i) Kates, S. A.; Minor, C. A.; Shroff, H.; Haaseth, R. C.; Triolo, S.; El-Faham, A.; Carpino, L. A.; Albericio, F. In Peptides 1994: Proceedings of the Twenty-Third European Peptide Symposium; Maia, H. L. S., Ed.; ESCOM: Leiden, The Netherlands, 1995; pp 248-249. (j) Carpino, L. A.; El-Faham, A. J. Am. Chem. Soc. 1995, 117, 5401-5402. (k) Carpino, L. A.; Beyermann, M.; Wenschuh, H.; Bienert, M. Acc. Chem. Res. 1996, 29, 268-274. (l) Albericio, F.; Carpino, L. A. Methods Enzymol. 1997, 289, 104-126.
59. The development and applications of the revelant coupling reagents are reported by the following: (a) Castro, B.; Dormoy, J. R.; Evin, G.; Selve, C. Tetrahedron Lett. 1975, 1219-1222. (b) Dourtoglou, V.; Ziegler, J.-C; Gross, B. Tetrahedron Lett. 1978, 1269-1272. (c) Fournier, A.; Wang, C. T.; Felix, A. M. Int. J. Pept. Protein Res. 1988, 31, 86-97. (d) Hudson, D. J. Org. Chem. 1988, 53, 617-624. (e) Knorr, R.; Trzeciak, A.; Bannwarth, W.; Gillessen, D. Tetrahedron Lett. 1989, 30, 1219-1222. (f) Frérot, E.; Coste, J.; Pantaloni, A.; Dufour, M.-N.; Jouin, P. Tetrahedron 1991, 47, 259-270. (g) Carpino, L. A. J. Am. Chem. Soc. 1993, 115, 4397-4398. (h) Carpino, L. A.; El-Faham, A.; Minor, C. A.; Albericio, F. J. Chem. Soc., Chem. Commun. 1994, 201-203. (i) Kates, S. A.; Minor, C. A.; Shroff, H.; Haaseth, R. C.; Triolo, S.; El-Faham, A.; Carpino, L. A.; Albericio, F. In Peptides 1994: Proceedings of the Twenty-Third European Peptide Symposium; Maia, H. L. S., Ed.; ESCOM: Leiden, The Netherlands, 1995; pp 248-249. (j) Carpino, L. A.; El-Faham, A. J. Am. Chem. Soc. 1995, 117, 5401-5402. (k) Carpino, L. A.; Beyermann, M.; Wenschuh, H.; Bienert, M. Acc. Chem. Res. 1996, 29, 268-274. (l) Albericio, F.; Carpino, L. A. Methods Enzymol. 1997, 289, 104-126.
60. The development and applications of the revelant coupling reagents are reported by the following: (a) Castro, B.; Dormoy, J. R.; Evin, G.; Selve, C. Tetrahedron Lett. 1975, 1219-1222. (b) Dourtoglou, V.; Ziegler, J.-C; Gross, B. Tetrahedron Lett. 1978, 1269-1272. (c) Fournier, A.; Wang, C. T.; Felix, A. M. Int. J. Pept. Protein Res. 1988, 31, 86-97. (d) Hudson, D. J. Org. Chem. 1988, 53, 617-624. (e) Knorr, R.; Trzeciak, A.; Bannwarth, W.; Gillessen, D. Tetrahedron Lett. 1989, 30, 1219-1222. (f) Frérot, E.; Coste, J.; Pantaloni, A.; Dufour, M.-N.; Jouin, P. Tetrahedron 1991, 47, 259-270. (g) Carpino, L. A. J. Am. Chem. Soc. 1993, 115, 4397-4398. (h) Carpino, L. A.; El-Faham, A.; Minor, C. A.; Albericio, F. J. Chem. Soc., Chem. Commun. 1994, 201-203. (i) Kates, S. A.; Minor, C. A.; Shroff, H.; Haaseth, R. C.; Triolo, S.; El-Faham, A.; Carpino, L. A.; Albericio, F. In Peptides 1994: Proceedings of the Twenty-Third European Peptide Symposium; Maia, H. L. S., Ed.; ESCOM: Leiden, The Netherlands, 1995; pp 248-249. (j) Carpino, L. A.; El-Faham, A. J. Am. Chem. Soc. 1995, 117, 5401-5402. (k) Carpino, L. A.; Beyermann, M.; Wenschuh, H.; Bienert, M. Acc. Chem. Res. 1996, 29, 268-274. (l) Albericio, F.; Carpino, L. A. Methods Enzymol. 1997, 289, 104-126.
61. The development and applications of the revelant coupling reagents are reported by the following: (a) Castro, B.; Dormoy, J. R.; Evin, G.; Selve, C. Tetrahedron Lett. 1975, 1219-1222. (b) Dourtoglou, V.; Ziegler, J.-C; Gross, B. Tetrahedron Lett. 1978, 1269-1272. (c) Fournier, A.; Wang, C. T.; Felix, A. M. Int. J. Pept. Protein Res. 1988, 31, 86-97. (d) Hudson, D. J. Org. Chem. 1988, 53, 617-624. (e) Knorr, R.; Trzeciak, A.; Bannwarth, W.; Gillessen, D. Tetrahedron Lett. 1989, 30, 1219-1222. (f) Frérot, E.; Coste, J.; Pantaloni, A.; Dufour, M.-N.; Jouin, P. Tetrahedron 1991, 47, 259-270. (g) Carpino, L. A. J. Am. Chem. Soc. 1993, 115, 4397-4398. (h) Carpino, L. A.; El-Faham, A.; Minor, C. A.; Albericio, F. J. Chem. Soc., Chem. Commun. 1994, 201-203. (i) Kates, S. A.; Minor, C. A.; Shroff, H.; Haaseth, R. C.; Triolo, S.; El-Faham, A.; Carpino, L. A.; Albericio, F. In Peptides 1994: Proceedings of the Twenty-Third European Peptide Symposium; Maia, H. L. S., Ed.; ESCOM: Leiden, The Netherlands, 1995; pp 248-249. (j) Carpino, L. A.; El-Faham, A. J. Am. Chem. Soc. 1995, 117, 5401-5402. (k) Carpino, L. A.; Beyermann, M.; Wenschuh, H.; Bienert, M. Acc. Chem. Res. 1996, 29, 268-274. (l) Albericio, F.; Carpino, L. A. Methods Enzymol. 1997, 289, 104-126.
62. The development and applications of the revelant coupling reagents are reported by the following: (a) Castro, B.; Dormoy, J. R.; Evin, G.; Selve, C. Tetrahedron Lett. 1975, 1219-1222. (b) Dourtoglou, V.; Ziegler, J.-C; Gross, B. Tetrahedron Lett. 1978, 1269-1272. (c) Fournier, A.; Wang, C. T.; Felix, A. M. Int. J. Pept. Protein Res. 1988, 31, 86-97. (d) Hudson, D. J. Org. Chem. 1988, 53, 617-624. (e) Knorr, R.; Trzeciak, A.; Bannwarth, W.; Gillessen, D. Tetrahedron Lett. 1989, 30, 1219-1222. (f) Frérot, E.; Coste, J.; Pantaloni, A.; Dufour, M.-N.; Jouin, P. Tetrahedron 1991, 47, 259-270. (g) Carpino, L. A. J. Am. Chem. Soc. 1993, 115, 4397-4398. (h) Carpino, L. A.; El-Faham, A.; Minor, C. A.; Albericio, F. J. Chem. Soc., Chem. Commun. 1994, 201-203. (i) Kates, S. A.; Minor, C. A.; Shroff, H.; Haaseth, R. C.; Triolo, S.; El-Faham, A.; Carpino, L. A.; Albericio, F. In Peptides 1994: Proceedings of the Twenty-Third European Peptide Symposium; Maia, H. L. S., Ed.; ESCOM: Leiden, The Netherlands, 1995; pp 248-249. (j) Carpino, L. A.; El-Faham, A. J. Am. Chem. Soc. 1995, 117, 5401-5402. (k) Carpino, L. A.; Beyermann, M.; Wenschuh, H.; Bienert, M. Acc. Chem. Res. 1996, 29, 268-274. (l) Albericio, F.; Carpino, L. A. Methods Enzymol. 1997, 289, 104-126.
63. The development and applications of the revelant coupling reagents are reported by the following: (a) Castro, B.; Dormoy, J. R.; Evin, G.; Selve, C. Tetrahedron Lett. 1975, 1219-1222. (b) Dourtoglou, V.; Ziegler, J.-C; Gross, B. Tetrahedron Lett. 1978, 1269-1272. (c) Fournier, A.; Wang, C. T.; Felix, A. M. Int. J. Pept. Protein Res. 1988, 31, 86-97. (d) Hudson, D. J. Org. Chem. 1988, 53, 617-624. (e) Knorr, R.; Trzeciak, A.; Bannwarth, W.; Gillessen, D. Tetrahedron Lett. 1989, 30, 1219-1222. (f) Frérot, E.; Coste, J.; Pantaloni, A.; Dufour, M.-N.; Jouin, P. Tetrahedron 1991, 47, 259-270. (g) Carpino, L. A. J. Am. Chem. Soc. 1993, 115, 4397-4398. (h) Carpino, L. A.; El-Faham, A.; Minor, C. A.; Albericio, F. J. Chem. Soc., Chem. Commun. 1994, 201-203. (i) Kates, S. A.; Minor, C. A.; Shroff, H.; Haaseth, R. C.; Triolo, S.; El-Faham, A.; Carpino, L. A.; Albericio, F. In Peptides 1994: Proceedings of the Twenty-Third European Peptide Symposium; Maia, H. L. S., Ed.; ESCOM: Leiden, The Netherlands, 1995; pp 248-249. (j) Carpino, L. A.; El-Faham, A. J. Am. Chem. Soc. 1995, 117, 5401-5402. (k) Carpino, L. A.; Beyermann, M.; Wenschuh, H.; Bienert, M. Acc. Chem. Res. 1996, 29, 268-274. (l) Albericio, F.; Carpino, L. A. Methods Enzymol. 1997, 289, 104-126.
64. The development and applications of the revelant coupling reagents are reported by the following: (a) Castro, B.; Dormoy, J. R.; Evin, G.; Selve, C. Tetrahedron Lett. 1975, 1219-1222. (b) Dourtoglou, V.; Ziegler, J.-C; Gross, B. Tetrahedron Lett. 1978, 1269-1272. (c) Fournier, A.; Wang, C. T.; Felix, A. M. Int. J. Pept. Protein Res. 1988, 31, 86-97. (d) Hudson, D. J. Org. Chem. 1988, 53, 617-624. (e) Knorr, R.; Trzeciak, A.; Bannwarth, W.; Gillessen, D. Tetrahedron Lett. 1989, 30, 1219-1222. (f) Frérot, E.; Coste, J.; Pantaloni, A.; Dufour, M.-N.; Jouin, P. Tetrahedron 1991, 47, 259-270. (g) Carpino, L. A. J. Am. Chem. Soc. 1993, 115, 4397-4398. (h) Carpino, L. A.; El-Faham, A.; Minor, C. A.; Albericio, F. J. Chem. Soc., Chem. Commun. 1994, 201-203. (i) Kates, S. A.; Minor, C. A.; Shroff, H.; Haaseth, R. C.; Triolo, S.; El-Faham, A.; Carpino, L. A.; Albericio, F. In Peptides 1994: Proceedings of the Twenty-Third European Peptide Symposium; Maia, H. L. S., Ed.; ESCOM: Leiden, The Netherlands, 1995; pp 248-249. (j) Carpino, L. A.; El-Faham, A. J. Am. Chem. Soc. 1995, 117, 5401-5402. (k) Carpino, L. A.; Beyermann, M.; Wenschuh, H.; Bienert, M. Acc. Chem. Res. 1996, 29, 268-274. (l) Albericio, F.; Carpino, L. A. Methods Enzymol. 1997, 289, 104-126.
65. The development and applications of the revelant coupling reagents are reported by the following: (a) Castro, B.; Dormoy, J. R.; Evin, G.; Selve, C. Tetrahedron Lett. 1975, 1219-1222. (b) Dourtoglou, V.; Ziegler, J.-C; Gross, B. Tetrahedron Lett. 1978, 1269-1272. (c) Fournier, A.; Wang, C. T.; Felix, A. M. Int. J. Pept. Protein Res. 1988, 31, 86-97. (d) Hudson, D. J. Org. Chem. 1988, 53, 617-624. (e) Knorr, R.; Trzeciak, A.; Bannwarth, W.; Gillessen, D. Tetrahedron Lett. 1989, 30, 1219-1222. (f) Frérot, E.; Coste, J.; Pantaloni, A.; Dufour, M.-N.; Jouin, P. Tetrahedron 1991, 47, 259-270. (g) Carpino, L. A. J. Am. Chem. Soc. 1993, 115, 4397-4398. (h) Carpino, L. A.; El-Faham, A.; Minor, C. A.; Albericio, F. J. Chem. Soc., Chem. Commun. 1994, 201-203. (i) Kates, S. A.; Minor, C. A.; Shroff, H.; Haaseth, R. C.; Triolo, S.; El-Faham, A.; Carpino, L. A.; Albericio, F. In Peptides 1994: Proceedings of the Twenty-Third European Peptide Symposium; Maia, H. L. S., Ed.; ESCOM: Leiden, The Netherlands, 1995; pp 248-249. (j) Carpino, L. A.; El-Faham, A. J. Am. Chem. Soc. 1995, 117, 5401-5402. (k) Carpino, L. A.; Beyermann, M.; Wenschuh, H.; Bienert, M. Acc. Chem. Res. 1996, 29, 268-274. (l) Albericio, F.; Carpino, L. A. Methods Enzymol. 1997, 289, 104-126.
66. The development and applications of the revelant coupling reagents are reported by the following: (a) Castro, B.; Dormoy, J. R.; Evin, G.; Selve, C. Tetrahedron Lett. 1975, 1219-1222. (b) Dourtoglou, V.; Ziegler, J.-C; Gross, B. Tetrahedron Lett. 1978, 1269-1272. (c) Fournier, A.; Wang, C. T.; Felix, A. M. Int. J. Pept. Protein Res. 1988, 31, 86-97. (d) Hudson, D. J. Org. Chem. 1988, 53, 617-624. (e) Knorr, R.; Trzeciak, A.; Bannwarth, W.; Gillessen, D. Tetrahedron Lett. 1989, 30, 1219-1222. (f) Frérot, E.; Coste, J.; Pantaloni, A.; Dufour, M.-N.; Jouin, P. Tetrahedron 1991, 47, 259-270. (g) Carpino, L. A. J. Am. Chem. Soc. 1993, 115, 4397-4398. (h) Carpino, L. A.; El-Faham, A.; Minor, C. A.; Albericio, F. J. Chem. Soc., Chem. Commun. 1994, 201-203. (i) Kates, S. A.; Minor, C. A.; Shroff, H.; Haaseth, R. C.; Triolo, S.; El-Faham, A.; Carpino, L. A.; Albericio, F. In Peptides 1994: Proceedings of the Twenty-Third European Peptide Symposium; Maia, H. L. S., Ed.; ESCOM: Leiden, The Netherlands, 1995; pp 248-249. (j) Carpino, L. A.; El-Faham, A. J. Am. Chem. Soc. 1995, 117, 5401-5402. (k) Carpino, L. A.; Beyermann, M.; Wenschuh, H.; Bienert, M. Acc. Chem. Res. 1996, 29, 268-274. (l) Albericio, F.; Carpino, L. A. Methods Enzymol. 1997, 289, 104-126.
67. Although initial reports (refs 21b,e,g,h) showed the structures of HBTU and HATU as uranium salts, it has been shown more recently that both compounds crystallize as aminium salts (guanidinium N-oxides). See: (a) Abdelmoty, I.; Albericio, F.; Carpino, L. A.; Foxman, B. M.; Kates, S. A. Lett. Pept. Sci. 1994, 1, 57-67. (b) Henklein, P.; Costisella, B.; Wray, V.; Domke, T.; Carpino, L. A.; El-Faham, A.; Kates, S. A.; Abdelmoty, I.; Foxman, B. M. In Peptides 1996: Proceedings of the Twenty-Fourth European Peptide Symposium; Ramage, R., Epton, R., Eds.; Mayflower Scientific; Kingswinford, England, 1998, in press.
68. Although initial reports (refs 21b,e,g,h) showed the structures of HBTU and HATU as uranium salts, it has been shown more recently that both compounds crystallize as aminium salts (guanidinium N-oxides). See: (a) Abdelmoty, I.; Albericio, F.; Carpino, L. A.; Foxman, B. M.; Kates, S. A. Lett. Pept. Sci. 1994, 1, 57-67. (b) Henklein, P.; Costisella, B.; Wray, V.; Domke, T.; Carpino, L. A.; El-Faham, A.; Kates, S. A.; Abdelmoty, I.; Foxman, B. M. In Peptides 1996: Proceedings of the Twenty-Fourth European Peptide Symposium; Ramage, R., Epton, R., Eds.; Mayflower Scientific; Kingswinford, England, 1998, in press.
69. Carpino, L. A.; Sadat-Aalaee, D.; Chao, H. G.; DeSeims, R. H. J. Am. Chem. Soc. 1990, 112, 9651-9652.
70. (a) Angell, Y. M.; García-Echeverría, C.; Rieh, D. H. Tetrahedron Lett. 1994, 35, 5981-5984.
71. (b) Angell, Y. M.; Thomas, T. L.; Flentke, G. R.; Rieh, D. H. J. Am. Chem. Soc. 1995, 117, 7279-7280.
72. (a) Wang, S. S. J. Am. Chem. Soc. 1973, 95, 1328-1333.
73. (b) Atherton, E.; Benoiton, N. L.; Brown, E.; Sheppard, R. C.; Williams, B. J. J. Chem. Soc., Chem. Commun. 1981, 336-337.
74. (c) Wang, S. S.; Tam, J. P.; Wang, S. B.; Merrifield, R. B. Int. J. Pept. Protein Res. 1981, 18, 459-467.
75. (a) Neugebauer, W.; Escher, E. Helv. Chim. Acta 1989, 72, 1319-1323.
76. (b) Swistok, J.; Tilley, J. W.; Danho, W.; Wagner, R.; Mulkerins, K. Tetrahedron Lett. 1989, 30, 5045-5048.
77. (c) Mergler, M.; Nyfeler, R. In Peptides 1992: Proceedings of the Twenty-Second European Peptide Symposium; Schneider, C. H., Eberle, A. N., Eds.; ESCOM: Leiden, The Netherlands, 1992; pp 177-178.
78. (d) Murphy, A. M.; Dagnino, R.; Vallar, P. L.; Trippe, A. J.; Sherman, S. L.; Lumpkin, R. H.; Tamura, S. Y.; Webb, T. R. J. Am. Chem. Soc. 1992, 114, 3156-3157.
79. (e) Wenschuh, H.; Beyermann, M.; Haber, H.; Seydel, J. K.; Krause, E.; Bienert, M.; Carpino, L. A.; El-Faham, A.; Albericio, F. J. Org. Chem. 1995, 60, 405-410.
80. (f) Fehrentz, J. A.; Paris, M.; Heitz, A.; Velek, J.; Wintemitz, F.; Martinez, J. J. Org. Chem. 1997, 62, 6792-6796.
81. +). Such branching did not occur in the text synthesis of H-Tyr-Gly-Gly-Phe-Leu-Phe-oh with tert-butyl protection of the alcohol.
82. Experiments to exploit this observation for intentional preparation of diketopiperazines have been reported elsewhere: del Fresno, M.; Alsina, J.; Royo, M.; Barany, G.; Albericio, F. Tetrahedron Lett. 1998, 39, 2639-2642.
83. (a) Gisin, B. F.; Merrifield, R. B. J. Am. Chem. Soc. 1972, 94, 3102-3106.
84. (b) Khosla, M. C.; Smeby, R. R.; Bumpus, F. M. J. Am. Chem. Soc. 1972, 94, 4721-4724.
85. (c) Giralt, E.; Eritja, R.; Pedroso, E. Tetrahedron Lett. 1981, 22, 3779-3782.
86. (d) Alsina, J.; Giralt, E.; Albericio, F. Tetrahedron Lett. 1996, 37, 4195-4198 and references therein.
87. An earlier synthesis directed at the same peptide, using all-Fmoc chemistry as had been done successfully for Leu-enkephalin with BAL-anchored Leu-OrBu, gave only 25% of the desired product along with 75% of the diketopiperazine cyclo(Phe-Leu).
88. This peptide was described first by: McMurray, J. S. Tetrahedron Lett. 1991, 32, 7679-7682. See also Kates et al. (ref 13d) for syntheses using side-chain anchoring strategies, with varying yields and purities depending on the point of cyclization.
89. Reviews: (a) Gordon, E. M.; Barrett, R. W.; Dower, W. J.; Fodor, S. P. A.; Gallop, M. A. J. Med. Chem. 1994, 37, 1385-1401; (b) Früchtel, J. S.; Jung, G. Angew. Chem., Int. Ed. Engl. 1996, 35, 17-42; Angew. Chem. 1996, 108, 19-44. (c) Thompson, L. A.; Ellman, J. A. Chem. Rev. 1996, 96, 555-600. (d) Hermkens, P. H. H.; Ottenheijm, H. C. J.; Rees, D. Tetrahedron 1996, 52, 4527-4554. (e) Lam, K. S.; Lebl, M.; Krchnák, V. Chem. Rev. 1997, 97, 411-448. (f) Nefzi, A.; Ostresh, J. M.; Houghten, R. A. Chem. Rev. 1997, 97, 449-472. (g) Combinatorial Chemistry, Synthesis and Application; Wilson, S. R., Czarnik, A. W., Eds.; Wiley: New York, 1997. (h) Annual Reports in Combinatorial Chemistry and Molecular Diversity; Moos, W. H., Pavia, M. R., Ellington, A. D., Kay, B. K., Eds.; ESCOM: Leiden, Netherlands, 1997; Vol. 1. (i) Barany, G.; Kempe, M. In A Practical Guide to Combinatorial Chemistry; Czarnik, A. W., DeWitt, S. H., Eds.; American Chemical Society: Washington, DC, 1997; pp 51-97 and other chapters in this monograph.
90. Reviews: (a) Gordon, E. M.; Barrett, R. W.; Dower, W. J.; Fodor, S. P. A.; Gallop, M. A. J. Med. Chem. 1994, 37, 1385-1401; (b) Früchtel, J. S.; Jung, G. Angew. Chem., Int. Ed. Engl. 1996, 35, 17-42; Angew. Chem. 1996, 108, 19-44. (c) Thompson, L. A.; Ellman, J. A. Chem. Rev. 1996, 96, 555-600. (d) Hermkens, P. H. H.; Ottenheijm, H. C. J.; Rees, D. Tetrahedron 1996, 52, 4527-4554. (e) Lam, K. S.; Lebl, M.; Krchnák, V. Chem. Rev. 1997, 97, 411-448. (f) Nefzi, A.; Ostresh, J. M.; Houghten, R. A. Chem. Rev. 1997, 97, 449-472. (g) Combinatorial Chemistry, Synthesis and Application; Wilson, S. R., Czarnik, A. W., Eds.; Wiley: New York, 1997. (h) Annual Reports in Combinatorial Chemistry and Molecular Diversity; Moos, W. H., Pavia, M. R., Ellington, A. D., Kay, B. K., Eds.; ESCOM: Leiden, Netherlands, 1997; Vol. 1. (i) Barany, G.; Kempe, M. In A Practical Guide to Combinatorial Chemistry; Czarnik, A. W., DeWitt, S. H., Eds.; American Chemical Society: Washington, DC, 1997; pp 51-97 and other chapters in this monograph.
91. Reviews: (a) Gordon, E. M.; Barrett, R. W.; Dower, W. J.; Fodor, S. P. A.; Gallop, M. A. J. Med. Chem. 1994, 37, 1385-1401; (b) Früchtel, J. S.; Jung, G. Angew. Chem., Int. Ed. Engl. 1996, 35, 17-42; Angew. Chem. 1996, 108, 19-44. (c) Thompson, L. A.; Ellman, J. A. Chem. Rev. 1996, 96, 555-600. (d) Hermkens, P. H. H.; Ottenheijm, H. C. J.; Rees, D. Tetrahedron 1996, 52, 4527-4554. (e) Lam, K. S.; Lebl, M.; Krchnák, V. Chem. Rev. 1997, 97, 411-448. (f) Nefzi, A.; Ostresh, J. M.; Houghten, R. A. Chem. Rev. 1997, 97, 449-472. (g) Combinatorial Chemistry, Synthesis and Application; Wilson, S. R., Czarnik, A. W., Eds.; Wiley: New York, 1997. (h) Annual Reports in Combinatorial Chemistry and Molecular Diversity; Moos, W. H., Pavia, M. R., Ellington, A. D., Kay, B. K., Eds.; ESCOM: Leiden, Netherlands, 1997; Vol. 1. (i) Barany, G.; Kempe, M. In A Practical Guide to Combinatorial Chemistry; Czarnik, A. W., DeWitt, S. H., Eds.; American Chemical Society: Washington, DC, 1997; pp 51-97 and other chapters in this monograph.
92. Reviews: (a) Gordon, E. M.; Barrett, R. W.; Dower, W. J.; Fodor, S. P. A.; Gallop, M. A. J. Med. Chem. 1994, 37, 1385-1401; (b) Früchtel, J. S.; Jung, G. Angew. Chem., Int. Ed. Engl. 1996, 35, 17-42; Angew. Chem. 1996, 108, 19-44. (c) Thompson, L. A.; Ellman, J. A. Chem. Rev. 1996, 96, 555-600. (d) Hermkens, P. H. H.; Ottenheijm, H. C. J.; Rees, D. Tetrahedron 1996, 52, 4527-4554. (e) Lam, K. S.; Lebl, M.; Krchnák, V. Chem. Rev. 1997, 97, 411-448. (f) Nefzi, A.; Ostresh, J. M.; Houghten, R. A. Chem. Rev. 1997, 97, 449-472. (g) Combinatorial Chemistry, Synthesis and Application; Wilson, S. R., Czarnik, A. W., Eds.; Wiley: New York, 1997. (h) Annual Reports in Combinatorial Chemistry and Molecular Diversity; Moos, W. H., Pavia, M. R., Ellington, A. D., Kay, B. K., Eds.; ESCOM: Leiden, Netherlands, 1997; Vol. 1. (i) Barany, G.; Kempe, M. In A Practical Guide to Combinatorial Chemistry; Czarnik, A. W., DeWitt, S. H., Eds.; American Chemical Society: Washington, DC, 1997; pp 51-97 and other chapters in this monograph.
93. Reviews: (a) Gordon, E. M.; Barrett, R. W.; Dower, W. J.; Fodor, S. P. A.; Gallop, M. A. J. Med. Chem. 1994, 37, 1385-1401; (b) Früchtel, J. S.; Jung, G. Angew. Chem., Int. Ed. Engl. 1996, 35, 17-42; Angew. Chem. 1996, 108, 19-44. (c) Thompson, L. A.; Ellman, J. A. Chem. Rev. 1996, 96, 555-600. (d) Hermkens, P. H. H.; Ottenheijm, H. C. J.; Rees, D. Tetrahedron 1996, 52, 4527-4554. (e) Lam, K. S.; Lebl, M.; Krchnák, V. Chem. Rev. 1997, 97, 411-448. (f) Nefzi, A.; Ostresh, J. M.; Houghten, R. A. Chem. Rev. 1997, 97, 449-472. (g) Combinatorial Chemistry, Synthesis and Application; Wilson, S. R., Czarnik, A. W., Eds.; Wiley: New York, 1997. (h) Annual Reports in Combinatorial Chemistry and Molecular Diversity; Moos, W. H., Pavia, M. R., Ellington, A. D., Kay, B. K., Eds.; ESCOM: Leiden, Netherlands, 1997; Vol. 1. (i) Barany, G.; Kempe, M. In A Practical Guide to Combinatorial Chemistry; Czarnik, A. W., DeWitt, S. H., Eds.; American Chemical Society: Washington, DC, 1997; pp 51-97 and other chapters in this monograph.
94. Reviews: (a) Gordon, E. M.; Barrett, R. W.; Dower, W. J.; Fodor, S. P. A.; Gallop, M. A. J. Med. Chem. 1994, 37, 1385-1401; (b) Früchtel, J. S.; Jung, G. Angew. Chem., Int. Ed. Engl. 1996, 35, 17-42; Angew. Chem. 1996, 108, 19-44. (c) Thompson, L. A.; Ellman, J. A. Chem. Rev. 1996, 96, 555-600. (d) Hermkens, P. H. H.; Ottenheijm, H. C. J.; Rees, D. Tetrahedron 1996, 52, 4527-4554. (e) Lam, K. S.; Lebl, M.; Krchnák, V. Chem. Rev. 1997, 97, 411-448. (f) Nefzi, A.; Ostresh, J. M.; Houghten, R. A. Chem. Rev. 1997, 97, 449-472. (g) Combinatorial Chemistry, Synthesis and Application; Wilson, S. R., Czarnik, A. W., Eds.; Wiley: New York, 1997. (h) Annual Reports in Combinatorial Chemistry and Molecular Diversity; Moos, W. H., Pavia, M. R., Ellington, A. D., Kay, B. K., Eds.; ESCOM: Leiden, Netherlands, 1997; Vol. 1. (i) Barany, G.; Kempe, M. In A Practical Guide to Combinatorial Chemistry; Czarnik, A. W., DeWitt, S. H., Eds.; American Chemical Society: Washington, DC, 1997; pp 51-97 and other chapters in this monograph.
95. Reviews: (a) Gordon, E. M.; Barrett, R. W.; Dower, W. J.; Fodor, S. P. A.; Gallop, M. A. J. Med. Chem. 1994, 37, 1385-1401; (b) Früchtel, J. S.; Jung, G. Angew. Chem., Int. Ed. Engl. 1996, 35, 17-42; Angew. Chem. 1996, 108, 19-44. (c) Thompson, L. A.; Ellman, J. A. Chem. Rev. 1996, 96, 555-600. (d) Hermkens, P. H. H.; Ottenheijm, H. C. J.; Rees, D. Tetrahedron 1996, 52, 4527-4554. (e) Lam, K. S.; Lebl, M.; Krchnák, V. Chem. Rev. 1997, 97, 411-448. (f) Nefzi, A.; Ostresh, J. M.; Houghten, R. A. Chem. Rev. 1997, 97, 449-472. (g) Combinatorial Chemistry, Synthesis and Application; Wilson, S. R., Czarnik, A. W., Eds.; Wiley: New York, 1997. (h) Annual Reports in Combinatorial Chemistry and Molecular Diversity; Moos, W. H., Pavia, M. R., Ellington, A. D., Kay, B. K., Eds.; ESCOM: Leiden, Netherlands, 1997; Vol. 1. (i) Barany, G.; Kempe, M. In A Practical Guide to Combinatorial Chemistry; Czarnik, A. W., DeWitt, S. H., Eds.; American Chemical Society: Washington, DC, 1997; pp 51-97 and other chapters in this monograph.
96. Reviews: (a) Gordon, E. M.; Barrett, R. W.; Dower, W. J.; Fodor, S. P. A.; Gallop, M. A. J. Med. Chem. 1994, 37, 1385-1401; (b) Früchtel, J. S.; Jung, G. Angew. Chem., Int. Ed. Engl. 1996, 35, 17-42; Angew. Chem. 1996, 108, 19-44. (c) Thompson, L. A.; Ellman, J. A. Chem. Rev. 1996, 96, 555-600. (d) Hermkens, P. H. H.; Ottenheijm, H. C. J.; Rees, D. Tetrahedron 1996, 52, 4527-4554. (e) Lam, K. S.; Lebl, M.; Krchnák, V. Chem. Rev. 1997, 97, 411-448. (f) Nefzi, A.; Ostresh, J. M.; Houghten, R. A. Chem. Rev. 1997, 97, 449-472. (g) Combinatorial Chemistry, Synthesis and Application; Wilson, S. R., Czarnik, A. W., Eds.; Wiley: New York, 1997. (h) Annual Reports in Combinatorial Chemistry and Molecular Diversity; Moos, W. H., Pavia, M. R., Ellington, A. D., Kay, B. K., Eds.; ESCOM: Leiden, Netherlands, 1997; Vol. 1. (i) Barany, G.; Kempe, M. In A Practical Guide to Combinatorial Chemistry; Czarnik, A. W., DeWitt, S. H., Eds.; American Chemical Society: Washington, DC, 1997; pp 51-97 and other chapters in this monograph.
97. Reviews: (a) Gordon, E. M.; Barrett, R. W.; Dower, W. J.; Fodor, S. P. A.; Gallop, M. A. J. Med. Chem. 1994, 37, 1385-1401; (b) Früchtel, J. S.; Jung, G. Angew. Chem., Int. Ed. Engl. 1996, 35, 17-42; Angew. Chem. 1996, 108, 19-44. (c) Thompson, L. A.; Ellman, J. A. Chem. Rev. 1996, 96, 555-600. (d) Hermkens, P. H. H.; Ottenheijm, H. C. J.; Rees, D. Tetrahedron 1996, 52, 4527-4554. (e) Lam, K. S.; Lebl, M.; Krchnák, V. Chem. Rev. 1997, 97, 411-448. (f) Nefzi, A.; Ostresh, J. M.; Houghten, R. A. Chem. Rev. 1997, 97, 449-472. (g) Combinatorial Chemistry, Synthesis and Application; Wilson, S. R., Czarnik, A. W., Eds.; Wiley: New York, 1997. (h) Annual Reports in Combinatorial Chemistry and Molecular Diversity; Moos, W. H., Pavia, M. R., Ellington, A. D., Kay, B. K., Eds.; ESCOM: Leiden, Netherlands, 1997; Vol. 1. (i) Barany, G.; Kempe, M. In A Practical Guide to Combinatorial Chemistry; Czarnik, A. W., DeWitt, S. H., Eds.; American Chemical Society: Washington, DC, 1997; pp 51-97 and other chapters in this monograph.
98. Reviews: (a) Gordon, E. M.; Barrett, R. W.; Dower, W. J.; Fodor, S. P. A.; Gallop, M. A. J. Med. Chem. 1994, 37, 1385-1401; (b) Früchtel, J. S.; Jung, G. Angew. Chem., Int. Ed. Engl. 1996, 35, 17-42; Angew. Chem. 1996, 108, 19-44. (c) Thompson, L. A.; Ellman, J. A. Chem. Rev. 1996, 96, 555-600. (d) Hermkens, P. H. H.; Ottenheijm, H. C. J.; Rees, D. Tetrahedron 1996, 52, 4527-4554. (e) Lam, K. S.; Lebl, M.; Krchnák, V. Chem. Rev. 1997, 97, 411-448. (f) Nefzi, A.; Ostresh, J. M.; Houghten, R. A. Chem. Rev. 1997, 97, 449-472. (g) Combinatorial Chemistry, Synthesis and Application; Wilson, S. R., Czarnik, A. W., Eds.; Wiley: New York, 1997. (h) Annual Reports in Combinatorial Chemistry and Molecular Diversity; Moos, W. H., Pavia, M. R., Ellington, A. D., Kay, B. K., Eds.; ESCOM: Leiden, Netherlands, 1997; Vol. 1. (i) Barany, G.; Kempe, M. In A Practical Guide to Combinatorial Chemistry; Czarnik, A. W., DeWitt, S. H., Eds.; American Chemical Society: Washington, DC, 1997; pp 51-97 and other chapters in this monograph.
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