Unprecedented Migration of N-Alkoxycarbonyl Groups in Protected Pyroglutaminol

<UFIGR ID="ol0069397n00001">Cleavage of an O-silyl ether in an N-BOC-protected pyroglutaminol using TBAF led to an unprecedented migration of the BOC group. An investigation of the mechanism, based on experimental data and quantum mechanical calculations, is presented. Similar migration was observed for N-Cbz and N-methoxycarbonyl groups.