Stereocontrolled Preparation of Diversely Trifunctionalized Cyclobutanes

Abstract

The expedient and stereoselective syntheses of small libraries of trifunctionalized cyclobutane scaffolds bearing an acid, an amine, and a third functional group are described. Starting from a single precursor, the readily available protected derivative of <i>all-cis</i>-2-amino-3-hydroxycyclobutane-1-carboxylic acid, <i>cis-trans</i> stereoisomers are obtained following an S_N2-type reaction, while <i>all-trans</i> stereoisomers are obtained using the same strategy preceded by a C1 epimerization reaction.