Novel Cinchona alkaloid derived ammonium salts as catalysts for the asymmetric synthesis of beta-hydroxy alpha-amino acids via aldol reactions

摘要

Using the cinchonidine-derived phase-transfer catalyst developed by Park and Jew as a lead structure,we have prepared novel chiral ammonium salts and investigated their efficacy for the preparation of p-hydroxy alpha-amino acids via asymmetric aldol reactions.The modifications were performed at C3 of the cinchonidine nucleus and include dimers as well as catalysts possessing electron-deficient alkyne and alkene moieties.Some of the new catalysts yielded improvements relative to the Park-Jew catalyst in the aldol reaction.