Cyclopropane amino acid ester dipeptide sweeteners

Abstract
A series of esters of L-aspartyl-l-aminocyclopropane carboxylic acid has been prepared and their sweet tastes determined. The sweetest ester prepared was about 300 times sweeter than sucrose. An attempt to use basic conditions during preparation of the dipeptide allyl ester led to succinimide formation of the aspartyl peptide even though the .beta.-carboxyl group was protected by a t-butyl ester function. The X-ray structure of the propyl ester (1c) was determined and its conformation is discussed.