Reagent-controlled asymmetric homologation of boronic esters by enantioenriched main-group chiral carbenoids

Organic Letters

Volumn 8, Issue 4, 2006, Pages 773-776

  Blakemore, Paul R ^a   Marsden, Stephen P ^b   Vater, Huw D ^b  

^a OREGON STATE UNIVERSITY   (United States)

^b UNIVERSITY OF LEEDS   (United Kingdom)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 33644783530     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol053055k     Document Type: Article

References (45)

1. (a) Catalytic Asymmetric Synthesis; Ojimia, I., Ed.; Wiley: New York, 2000.
2. (b) Stereoselective Synthesis; Helmchen, G., Hoffmann, R. W., Mulzer, J., Schaumann, E., Eds.; Thieme: Stuttgart, 1995.
3. (c) Asymmetric Catalysis in Organic Synthesis; Noyori, R., Ed.; Wiley: New York, 1994.
4. (d) Hoveyda, A. H.; Evans, D. A.; Fu, G. C. Chem. Rev. 1993, 93, 1307.
5. The common observation of matching and mismatching of substrate/ reagent pairs in "double" asymmetric synthesis is a manifestation of this fundamental weakness; see: Asymmetric Synthesis; Procter, G., Ed.; Oxford University Press: Oxford, 1996.
6. For recent synthetic applications of 1,2-metalate rearrangements, see: (a) Jarowicki, K.; Kocienski, P. J. Synlett 2005, 167.
7. (b) Abramovitch, A.; Varghese, J. P.; Marek, I. Org. Lett. 2004, 6, 621.
8. (c) Pommier, A.; Stepanenko, V.; Jarowicki, K.; Kocienski, P. J. J. Org. Chem. 2003, 68, 4008.
9. (d)Le Menez, P.; Brion, J.-D.; Lensen, N.; Chelain, E.; Pancrazi, A.; Ardisson, J. Synthesis 2003, 2530.
10. (e) Kasatkin, A. N.; Whitby, R. J. Tetrahedron Lett. 2000, 41, 6201.
11. (f) Sidduri, A.; Rozema, M. K.; Knochel, P. J. Org. Chem. 1993, 58, 2694 and references therein.
12. Presented in part at the 229th ACS National Meeting, San Diego, CA, March 13-17, 2005; Blakemore, P. R.; Vater, H. D. paper ORGN 269.
13. Matteson, D. S.; Mah, R. W. H. J. Am. Chem. Soc. 1963, 85, 2599.
14. Hoffmann, R. W.; Nell, P. G.; Leo, R.; Harms, K. Chem. Eur. J. 2000, 6, 3359.
15. A stereoretentive electrophilic substitution (transmetalation) reaction between an enantioenriched secondary Grignard reagent and a borate ester has been reported, see: Hoffmann, R. W.; Hölzer, B.; Knopff, O. Org. Lett. 2001, 3, 1945.
16. 2O was found to be superior to acetone (as reported by Hoffmann) for the purpose of obtaining this compound in an isomerically homogeneous form (single stereoisomer by chiral HPLC analysis after three recrystallation cycles).
17. In each case, no deuterium was incorporated into sulfoxide 10 and the level of deuterium incorporation in 11 was 90%; % ee for 10 and 11 was not determined.
18. % ee for epoxides cis-12 and trans-12 was determined by HPLC analysis. Hoffmann and co-workers reported 69% overall yield for a closely related transformation employing EtMgBr in place of EtMgCl and found cis:trans = 88:12 and % ee (cis-12) = 93 ±3% (see ref 6). Diastereoselectivity in this type of addition has been studied in detail; see: Schulze, V.; Nell, P. G.; Burton, A.; Hoffmann, R. W. J. Org. Chem. 2003, 68, 4546.
19. Satoh and co-workers have investigated many other aspects of the chemistry of α-halo Grignard species. For recent work, with leading references, see: (a) Satoh, T.; Ogino, Y.; Ando, K. Tetrahedron 2005, 61, 10262.
20. (b) Miyashita, K.; Satoh, T. Tetrahedron 2005, 61, 5067.
21. (c) Satoh, T.; Musashi, J.; Kondo, A. Tetrahedron Lett. 2005, 46, 599.
22. (d) Satoh, T.; Kondo, A.; Musashi, J. Tetrahedron 2004, 60, 5453.
23. (a) Sadhu, K. M.; Matteson, D. S. Organometallics 1985, 4, 1687.
24. (b) Michnick, T. J.; Matteson, D. S. Synlett 1991, 631.
25. (c) Wallace, R. H.; Zong, K. K. Tetrahedron Lett. 1992, 33, 6941.
26. (d) Soundararajan, R.; Li, G.; Brown, H. C. Tetrahedron Lett. 1994, 35, 8957.
27. 2 species (X = Cl, Br) has been extensively studied by Matteson and co-workers and constitutes an important method for substrate controlled asymmetric chain extension. For reviews, see: (a) Matteson, D. S. Tetrahedron 1998, 54, 10555.
28. (b) Matteson, D. S. Chem. Rev. 1989, 89, 1535.
29. For recent applications, see: (c) Hiscox, W. C.; Matteson, D. S. J. Organomet. Chem. 2000, 614-615, 314.
30. (d) Davoli, P.; Spaggiari, A.; Castagnetti, L.; Prati, F. Org. Biomol. Chem. 2004, 2, 38.
31. Matteson, D. S.; Majumdar, D. Organometallics 1983, 2, 230.
32. 2X species have been encountered, see: Ren, L.; Crudden, C. M. Chem. Commun. 2000, 721.
33. α-Haloalkylmetal reagents are relatively poor nucleophiles and in many of their characteristic reactions are best considered as electrophilic species, see: Boche, G.; Lohrenz, J. C. W. Chem. Rev. 2001, 101, 697.
34. 2.
35. For discussion of this topic as it relates to organolithiums, see ref 22.
36. 1H NMR analysis of its derived MTPA-ester according to Mosher's method: Dale, J. A.; Mosher, H. S. J. Am. Chem. Soc. 1973, 95, 512.
37. To establish absolute configuration for ent-23, an authentic sample of its antipode was prepared by enantioselective reduction of benzyl cyclohexyl ketone with (S)-methyl-CBS-oxazaborolidine according to Corey's method: Corey, E. J.; Helal, C. J. Angew. Chem., Int. Ed. 1998, 37, 1986. See Supporting Information for details.
38. Satoh, T.; Takano, K. Tetrahedron 1996, 52, 2349.
39. Hoffmann and co-workers have demonstrated that α-bromo- alkyllithiums are configurationally stable for short periods of time at -110 °C. See: (a) Hoffmann, R. W.; Ruhland, T.; Bewersdorf, M. J. Chem. Soc., Chem. Commun. 1991, 195.
40. (b) Hoffmann, R. W.; Bewersdorf, M. Chem. Ber. 1991, 124, 1249.
41. (c) Hoffmann, R. W.; Julius, M.; Chemla, F.; Ruhland, T.; Frenzen, G. Tetrahedron 1994, 50, 6049.
42. For reviews concerning the configurational stability of organolithium species, see: (a) Organolithiums: Selectivity for Synthesis; Clayden, J., Ed.; Pergamon: New York, 2002.
43. (b) Basu, A.; Thayumanavan, S. Angew. Chem., Int. Ed. 2002, 41, 716.
44. Carbenoid 26 presumably decomposed via β-hydrogen insertion and dimerization pathways; see: Carbene Chemistry; Kirmse, W., Ed.; Academic Press: New York, 1971.
45. The expected exchange product from this reaction, butyl p-tolyl sulfoxide, was also isolated (53% based on 8), as were phenethyl chloride (10% based on 8) and recovered chlorosulfoxide 8 (23%). The latter exhibited significant epimerization (dr (syn:anti) = 48:52), believed to be the result of deprotonation by BuLi followed by poorly diastereoselective reprotonation upon quench. Satoh and Takano reported that alkyllithium-mediated ligand exchange from sulfoxide substrates possessing acidic α-hydrogen atoms is complicated by competing deprotonation. See ref 20.