Asymmetric alkylation catalyzed by chiral alkali metal alkoxides of TADDOL. Synthesis of alpha-methyl amino acids

Authors
Belokon, YN Kochetkov, KA Churkina, TD Ikonnikov, NS Chesnokov, AA Larionov, OV Kagan, HV
Citation
Yn. Belokon et al., Asymmetric alkylation catalyzed by chiral alkali metal alkoxides of TADDOL. Synthesis of alpha-methyl amino acids, RUSS CHEM B, 48(5), 1999, pp. 917-923
Citations number
28
Categorie Soggetti
Chemistry
Journal title
RUSSIAN CHEMICAL BULLETIN
ISSN journal
10665285 → ACNP
Volume
48
Issue
5
Year of publication
1999
Pages
917 - 923
Database
ISI
SICI code
1066-5285(199905)48:5<917:AACBCA>2.0.ZU;2-3
Abstract
It is shown that sodium alkoxides formed from (4R,SR)-2,2-dimethyl-1,3-diox olane-4,5-bis(diphenylmethanol) ((R,R)-TADDOL) and some of its derivatives can be used as chiral catalysts for enantioselective alkylation of Schiff's bases derived from alanine with reactive alkyl halides. Acid hydrolysis of the reaction products affords (R)-alpha-methylphenyl-alanine, (R)-alpha-al lylalanine, and (R)-alpha-methytnaphthylalanine in 61-93% yields and with e e 69-94%. When (S,S)-TADDOL is used, the (S)-amino acid is formed. A mechan ism explaining the observed features of the reaction is proposed.