Expedient Preparation of All Isomers of2-Aminocyclobutanecarboxylic Acid inEnantiomerically Pure Form

摘要

A short, convenient, gram scale protocol has been establishedto allow facile access to all four stereoisomers of 2-ami-nocyclobutanecarboxylic acid, each in enantiomerically pureform (ee >99%). Starting from the readily available cisracemate, the procedure combines efficient a-phenylethy-lamine derivative resolution and controlled cis-to-transepimerization procedures, and proceeds with invariably highyields.