Combinatorial design of simplified high-performance chiral phase-transfer catalysts for practical asymmetric synthesis of alpha-alkyl- and alpha,alpha-dialkyl-alpha-amino acids.
A very efficient, chiral phase-transfer catalyst, (S)-2 Db, was prepared by taking advantage of the combinatorial approach from the readily available (S)-1,1'-binaphthyl-2,2'-dicarboxylic acid. This catalyst exhibited high catalytic performance (0.01-0.1 mol %) in the asymmetric alkylation of N-(diphenylmethylene)glycine tert-butyl ester and N-(p-chlorophenylmethylene)alanine tert-butyl ester relative to other chiral phase-transfer catalysts in current use. This has created a general and highly practical procedure for the enantioselective synthesis of structurally diverse natural and unnatural alpha-alkyl-alpha-amino acids as well as alpha,alpha-dialkyl-alpha-amino acids. A similar simplified catalyst, (S)-2 Fb, is also applicable to the direct asymmetric aldol reaction between glycine Schiff base and aldehydes with moderate syn selectivity and high enantioselectivity.
Kitamura
Masanori
M
Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Japan.
Shirakawa
Seiji
S
Arimura
Yuichiro
Y
Wang
Xisheng
X
Maruoka
Keiji
K
D000478:Alkylation; D000596:Amino Acids / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D020650:Combinatorial Chemistry Techniques; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D015394:Molecular Structure; D013237:Stereoisomerism
D000596:Amino Acids