Chemoselective hydrolysis of tert-butyl esters inthe presence of other acid-labile groups has been exploredby employing α-amino esters and ZnBr2 in DCM. AlthoughN-Boc and N-trityl groups were found to be labile, PhFprotected amines were compatible with these Lewis aciddeprotection conditions such that a variety of N-(PhF)aminoacids were prepared in good yields from their correspondingtert-butyl esters.
