Synthesis of 4-substituted phenylalanines by cross-coupling reactions: Extension of the methodology to aryl chlorides

Tetrahedron Letters

Volumn 39, Issue 23, 1998, Pages 3985-3988

  Firooznia, Fariborz ^a   Gude, Candido ^a   Chan, Kenneth ^a   Satoh, Yoshitaka ^a  

^a NOVARTIS PHARMA AG   (Switzerland)

Author keywords

[No Author keywords available]

Indexed keywords

BORONIC ACID DERIVATIVE; CHLORIDE; PHENYLALANINE DERIVATIVE;

ARTICLE; CATALYSIS; REACTION ANALYSIS; SYNTHESIS;

EID: 0032482519     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0040-4039(98)00749-7     Document Type: Article

References (16)

1. (1) For a recent review, see: Miyaura, N.; Suzuki, A. Chem. Rev. 1995, 95, 2457.
2. (2) Satoh, Y.; Gude, C.; Chan, K.; Firooznia, F. Tetrahedron Lett. 1997, 38, 7645.
3. (3) (a) Subsequent to our report (ref. 2), a recent publication described a synthesis of 4-aryl and 4-vinylphenylalanines by Stille cross-coupling reactions of N-Boc-4-trimethylstannylphenylalanine methyl ester. Morera, E.; Ortar, G. Synlett 1997, 1403.
4. (b) For a review of other approaches for the synthesis of unnatural amino acids, see: Williams, R. M. Synthesis of Optically Active α-Amino Acids; Pergamon Press: Oxford, 1989.
5. (4) (a) Indolese, A. F. Tetrahedron Lett. 1997, 38, 3513.
6. (b) Saito, S.; Oh-Tani, S.; Miyaura, N. J. Org. Chem. 1997, 62, 8024.
7. (5) Shen, W. Tetrahedron Lett. 1997, 38, 5575.
8. 2(dppb) as the catalyst, see: Mitchell, M. B.; Wallbank, P. J. Tetrahedron Lett. 1991, 32, 2273.
9. (7) For palladium-catalyzed coupling reactions of aryl chlorides and tetraphenylborate sodium, see: Bumagin, N. A.; Bykov, V. Tetrahedron 1997, 53, 14437, and references cited therein.
10. (8) (a) Firooznia, F.; Gude, C. unpublished results.
11. (b) N. Miyaura, private communication.
12. 2(dppf) as the catalyst for the coupling reactions, since the ligands on Pd were not labile phosphine groups that could be easily replaced with the imine functionality.
13. 6B 420 (M+1).
14. 4 395 (M+1).
15. 6B 338 (M+1), 336 (M-1).
16. (13) The boronate ester 6 is more readily purified by chromatography on silica gel than the more polar 8. Moreover, 8 is often contaminated with its trimer, a problem common to boronic acids.