Iron(II)-Catalyzed Activation of Si–N and Si–O Bonds Using Hydroboranes

Abstract

We report the activation and functionalization of Si–N bonds with pinacol borane catalyzed by a three-coordinate iron­(II) β-diketiminate complex. The reactions proceed via the mild activation of silazanes to yield useful hydrosilanes and aminoboranes. The reaction is studied by kinetic analysis, along with a detailed investigation of decomposition pathways using catecholborane as an analogue of the pinacol borane used in catalysis. We have extended the methodology to develop a polycarbosilazane depolymerization strategy, which generates hydrosilane quantitatively along with complete conversion to the Bpin-protected diamine. The analogous Si–O bond cleavage can also be achieved with heating, using silyl ether starting materials to generate hydrosilane and alkoxyborane products. Depolymerization of poly­(silyl ether)­s using our strategy successfully converts the polymer to 90% Bpin-protected alcohols.