In the course of studies designed to investigate peptide trmspnrt, in biological systems,' tripeptides of l-aminocyclopentane-1-carboxylic acid (cycloleucine)2 were needed. The present report is concerned with the synthesis of glycylcycloleuc+Lvaline and glycylcycloleucyl-alanine. A number of other cgcloleucine peptides have previously been synthesized fly authors interested in the tumor growth inhibition shoxn by cy~loleucine.~-6 Transport, studies with Lactobucillus casci 7469 have shown that this organism has pathways for the uptake of tripeptides distinct from those for the nptake of free amino :icids.'
Experimental*Carbobenzoxyglycylcycloleucine Ethyl Ester (I).-To a solution containing 5.8 g. (0.03 mole) of cycloleucine ethyl ester hydrochloride,3 4.2 i d . (0.03 mole) of triethylamine, and 6.3 g. (0.03 mole) of carbobenzoxyglycine in 150 ml. of methylene chloride, G.2 g. (0.03 mole) of dicyclohexylcarbodiimide xa,s added. The mixture was stirred for 16 hr. in a cold room (4"). filtered to remove dicyclohexylurea, washed successively with 0.5 -V HCI, 0.5 N iYaHC03, and m t e r , and dried overnight (Nal-
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.