Because of the importance of hydrogen atom transfer (HAT) in biology and chemistry, there is increased interest in new strategies to perform HAT in a sustainable manner. Here, we describe a sustainable, net redox-neutral HAT process involving hydrosilanes and alkali metal Lewis base catalysts - eliminating the use of transition metal catalysts - and report an associated mechanism concerning Lewis base-catalysed, complexation-induced HAT (LBCI-HAT). The catalytic LBCI-HAT is capable of accessing both branch-specific hydrosilylation and polymerization of vinylarenes in a highly selective fashion, depending on the Lewis base catalyst used. In this process, earth abundant, alkali metal Lewis base catalyst plays a dual role. It first serves as a HAT initiator and subsequently functions as a silyl radical stabilizing group, which is critical to highly selective cross-radical coupling. EPR study identified a potassiated paramagnetic species and multistate density function theory revealed a high HAT character, yet multiconfigurational nature in the transition state of the reaction.
Bibliographical noteFunding Information:
We are grateful for financial support from the National Institutes of Health (NIGMS; GM116031 to J.J. and GM117511-01 to B.S.P.), ACS Petroleum Research Fund (PRF number 54831-DNI1 to J.J.), National Science Foundation (CHE; 1709369 to B.S.P.), Swedish Research Council (VR 2015-04114 to K.N.) and University of Texas at Arlington (to K.N.). We acknowledge the NSF (CHE-0234811 and CHE-0840509) for partial funding of the purchases of the NMR spectrometers used in this work.
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