Among the carbonic acid derivatives used as protecting groups, tert-butyl carbonates and carbamates are of great importance in organic chemistry due to both their resistance to nucleophilic reagents and ease of removal under specific conditions. 1 We previously reported on the use of 1-tert-butoxy-2-tert-butoxycarbonyl-1,2-dihydroisoquinoline (BBDI) prepared by the reaction of isoquinoline with Boc 2 O as a novel and chemoselective tert-butoxycarbonylation ...