Calcium-Catalyzed Dehydrogenative Silylation of Aromatic Ethers with Hydrosilane

The catalytic regioselective C–H silylation of a wide range of alkoxy-substituted benzene derivatives with primary hydrosilane was achieved by the use of scorpionate-supported calcium benzyl complex [(TpAd,iPr)­Ca­(p-CH2C6H4Me)­(THP)] (1) (TpAd,iPr = hydrotris­(3-adamantyl-5-isopropylpyrazolyl)­borate, THP = tetrahydropyran) as the precatalyst. This protocol offers an atom-efficient and straightforward method for the synthesis of a variety of silyl-substituted aromatic ether derivatives without a hydrogen acceptor and free of transition metal. Calcium anisyl complexes [(TpAd,iPr)­Ca­(o-MeO-m-Br-C6H3)] (5) and [(TpAd,iPr)­Ca­(o-Me-OCH2C6H4)] (6), proposed as the catalytic reaction intermediates, were isolated and structurally characterized.