Triethylsilane Carbocation Scavenger for Boc Deprotection

Abstract

The use of triethylsilane as a carbocation scavenger in the presence of trifluoroacetic acid in dichloromethane leads to increased yields, decreased reaction times, simple work-up and improved selectivity for the deprotection of t-butyl ester and t-butoxycarbonyl sites in protected amino-acids and peptides in the presence of other acid-sensitive protecting groups such as the benzyloxycarbonyl, 9-fluorenylmethoxycarbonyl, O- and S-benzyl and t-butylthio groups. A mild procedure is described for Boc and tbutyl ester removal by Et3SiH/TFA (in the presence of Z, Fmoc, BzlS, BzlO and ButS groups) and does not lead to trytophan side-chain reduction.