Synthesis of (+)-(1S,2R) and (-)-(1R,2S)-2-aminocyclobutane-1-carboxylic acids

(+)-(I S,2R) and (-)-(I R,2S)-2-aminocyclobutane-1-carboxylic acids have been prepared in >97% ee and in 33% and 20% overall yields starting from a single, chiral, bicyclic compound perceived as a chiral uracil equivalent. Construction of the cyclobutane ring is achieved via a [2+2] photocycloaddition reaction of this chiral precursor with ethylene. (C) 2004 Elsevier Ltd. All rights reserved.