Hydroxy- and amino-protection based on the 4-dimethylcarbamoylbenzyl group

0-4-Dimethylcarbamoylbenzyl-L-tyrosine, N (epsilon)-4-dimethylcarbamoylbenzyloxycarbonyl-L-lysine, and simple derivatives, have been prepared. The protecting groups are markedly more stable to trifluoroacetic acid than are the unsubstituted benzylanalogues. N-t-Butoxycarbonyl-O-4-dimethylcarbamoylbenzyl-L-serine (cyclohexylammonium salt) is also described.