Novel α-amino squaric acid analogs were synthesized by initial addition reaction of a dianion enolate generated from N-Boc aminoacid tert-butyl ester to squaric acid diisopropyl ester, and subsequent decarboxylation of the resulting carboxylic acid moiety.
A simple, mild and efficient method for the hydrolysis of tert-butyl esters using molecular iodine as a catalyst is described. Acid labile protecting groups, such as N-Boc, OBn, OAc and double bonds, are compatible under the reaction conditions.