Synthesis of Both Enantiomers of Chiral Phenylalanine Derivatives Catalyzed by Cinchona Alkaloid Quaternary Ammonium Salts as Asymmetric Phase Transfer Catalysts.

ABSTRACT: A practical synthesis of both enantiomers of unnatural phenylalanine derivatives by using two pseudoenantiomeric phase transfer catalysts is described. Through asymmetric ?-alkylation of glycine Schiff base with substituted benzyl bromides and 1-(bromomethyl)naphthalene under the catalysis of O-allyl-N-(9-anthracenmethyl) cinchoninium bromide (1f) and O-allyl-N-(9-anthracenylmethyl)cinchonidium bromide (1i), respectively, a series of both (R)- and (S)-enantiomers of unnatural ?-amino acid derivatives were obtained in excellent yields and enantioselectivity. The synthetic method is simple and scalable, and the stereochemistry of the products is fully predictable and controlled: the cinchonine-type phase transfer catalyst 1f resulted in (R)-?-amino acid derivatives, and the cinchonidine-type phase transfer catalyst 1i afforded (S)-?-amino acid derivatives.

SUBMITTER: Jin L 

PROVIDER: S-EPMC6099405 | biostudies-literature | 2018 Jun

REPOSITORIES: biostudies-literature