The formation of a novel Pd/C-ethylenediamine complex catalyst: Chemoselective hydrogénation without deprotection of the o-benzyl and ZV-Cbz groups

Journal of Organic Chemistry

Volumn 63, Issue 22, 1998, Pages 7990-7992

  Sajiki, Hironao ^a   Hattori, Kazuyuki ^a   Hirota, Kosaku ^a  

^a GIFU PHARMACEUTICAL UNIVERSITY   (Japan)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 0001345246     PISSN: 00223263     EISSN: None     Source Type: Journal    
DOI: 10.1021/jo9814694     Document Type: Article

References (38)

1. (a) Freifelder, M. In Practical Catalytic Hydrogénation Techniques and Applications; Wiley-Interscience: New York, 1971; p 398.
2. (b) Rylander, P. N. In Catalytic Hydrogénation in Organic Synthesis; Academic Press: New York, 1979; p 271.
3. (c) Idem. In Hydrogénation Methods; Academic Press: New York, 1985; p 157.
4. (d) Siegel, S. In Comprehensive Organic Synthesis; Trost, B. M., Fleming, I., Eds.; Pergamon Press: New York, 1991; Vol. 8, p 417.
5. (e) Hudlicky, M. In Reductions in Organic Chemistry; American Chemical Society: Washington, DC, 1996.
6. An ingenious Pd-based catalyst using catalyst poisons for the improvement of the desired selectivity is represented by the Lindlar catalyst: (a) Lindlar, H. Helv. Chim. Acta 1953, 35, 446.
7. (b) Ulan, J. G.; Kuo, E.; Maier, F.; Rai, R. S.; Thomas, G. J. Org. Chem. 1987, 52, 3126.
8. (c) Ulan, J. G.; Maier, W. F.; Smith, D. A. J. Org. Chem. 1987 752, 3132 and references therein.
9. (a) Sajiki, H. Tetrahedron Lett. 1995, 36, 3465.
10. 2 to form benzyl undecyl ether: Czech, B. P.; Bartsh, R. A. J. Org. Chem. 1984, 49, 4077.
11. Sajiki, H.; Kuno, H.; Hirota, K. Tetrahedron Lett. 1997,38, 399.
12. Control experiment was run with no ethylenediamine in the presence of the commercial 5% Pd/C for the hydrogénation of 1 in MeOH. The hydrogénation does not tolerate the O-benzyl protective group of 1 even after 30 h prestirring.
13. The catalysts used were 5% Pd/C (Aldrich, Nakarai or Kishida), and no difference in the quality among 5% Pd/C(en) catalysts was detected depending upon their supplier.
14. The mixture was stirred for appropriate time (48 h) just to make sure.
15. 5% Pd/C(en) catalyst contains 1.35-1.75% nitrogen.
16. The zerovalent Pd complexes that consist of an electron-rich d10 metal center with an electron-donating nitrogen ligand should (A) be stabilized with an electron-accepting species or (B) be supported by a polymer-backbone. (A) For examples: (a) Cavell, K. J.; Stufkens, D. J.; Vrieze, K. Inorg.- Chim. Acta 1980, 47, 67.
17. (b) Sustmann, R.; Lau, J.; Zipp, M. Tetrahedron Lett. 1986, 705, 356.
18. (c) Idem. Keel. Trav. Chim. Pays-Bas 1986, 705, 356.
19. (d) van Asselt, R; Eisevier: C. J.; Smeets, W. J. J.; Spek, A. L. Inorg. Chem. 1994, 33, 1521.
20. (e) Klein, R. A.; Witte, P.; van Beizen, R.; Fraanje, J.; Goubitz, K.; Numan, M.; Schenk, H.; Ernsting, J. M.; Elscvier: C. J. Eur. J. Inorg. Chem. 1998, 379, 9 and references therein. (B) For examples
21. (f) Card, R. J.; Neckers, D. C. J. Am. Chem. Soc. 1977, 99, 9, 7733.
22. (g) Idem. Inorg. Chem. 1978, 77, 2345.
23. (h) Idem. Isr. J. Chem. 1978, 77, 269.
24. (i) Card, R. J.; Liesner, C. E.; Neckers, D. C. J. Org. Chem. 1979, 44, 1095.
25. Maier, W. F.; Chettle, S. J.; Rai, R. S.; Thomas, G. J. Am. Chem. Soc. 1986, 108, 2608.
26. Ghosh and Krishnan have recently reported a chemoselective catalytic hydrogénation of alkenes using the Lindlar catalyst. In their report, they mentioned that the N-Cbz protective group does not survive even using the Lindlar catalyst: Ghosh, A. K.; Krishnan, K. Tetrahedron Lett. 1998, 39, 947.
27. A feature of the hydrogénation of an N-Cbz derivatives is that the catalyst activity of Pd/C(en) toward the N-Cbz protective group is strongly influenced by the solvent. The N-Cbz group of AT-Cbz-diallylamine and Af-Cbz-propargylamine were completely deprotected in MeOH as a solvent within only 3 and 0.5 h, respectively. However, no deprotection of the N-Cbz group was observed in THF as a solvent as can be seen from entries 13 and 14. Further, limitations of this methodology are that complete deprotection of the N-Cbz protective group of aromatic amine would be observed even in THF.
28. Green, T. W.; Wuts, P. G. In Protective Groups in Organic Synthesis; 2nd ed.; John Wiley & Sons: New York, 1991; p 335 and references therein.
29. Al though the hydrogénation of Boc-Tyr(Bn)-OMe, which does not possess a carboxylic acid moiety, gave only recovery (Table 1, entry 8), the addition of AcOH to the reaction mixture resulted in a hydrogenolysis of the benzyl group to give Boc-Tyr-OMe in 95% yield.
30. 16 using 5% Pd/C(en) catalyst in AcOH as a solvent for 50 h also gave only recovery.
31. (a) Torii, S.; Takagishi, S.; Inokuchi, T.; Okumoto, H. Bull. Chern. Soc. Jpn. 1987, 60, 775.
32. (b) Akiyama, T.; Hirofuji, H.; Ozaki, S. Ibid. Bull. Chern. Soc. Jpn. 1992, 65, 1932.
33. 3OBn was not observed no matter how great a pressure (42 atm, 24 h) of hydrogen was applied.
34. Balderman, D.; Kalir, A. Synthesis 1978, 24.
35. (a) Lappas, L. C.; Jenkins, G. L. J. Am. Pharm. Assoc. Sei. Ed. 1952,41, 257.
36. (b) Armarego, W. L. F.; Milloy, B. A.; Pendergast, W. J. Chem. Soc., Ferkln Trans. 1 1976, 2229.
37. (c) Bernotas, R. C.; Cube, R. V. Synth. Commun. 1990, 20, 1209.
38. 3OBn was smoothly hydrogenolyzed with 5% PoVC(en) in the presence of coned HC1 in MeOH.