Organoaluminum Cation Catalyzed Selective Hydrosilylation of Carbonyls, Alkenes, and Alkynes
Nabin Sarkar, Rajata Kumar Sahoo, Sayantan Mukhopadhyay, Sharanappa Nembenna
Abstract
Abstract The N , N’ ‐chelated β ‐diketiminate analogue i. e ., conjugated bis‐guanidine (CBG) ligand L(3H) [L= {(ArHN)(ArN)−C=N−C=(NAr)(NHAr)}; Ar=2,6‐Et 2 ‐C 6 H 3 ], has been used to synthesize mono‐ and dinuclear Al(III) dimethyl complexes, [L(2H) AlMe 2 ] ( 1) and [L(H)(AlMe 2 ) 2 ] ( 2 ). Compounds 1 and 2 are synthesized by deprotonation method using free ligand and appropriate stoichiometric amounts of AlMe 3 and are structurally characterized by a single‐crystal X‐ray diffraction technique. Moreover, the reaction of compound 1 with B(C 6 F 5 ) 3 afforded a three‐coordinate aluminum methyl cation [L(2H)AlMe] + [MeB(C 6 F 5 ) 3 ] − 3 in good yield. Compound 3 was thermally stable and characterized by multinuclear NMR spectroscopy. Furthermore, we demonstrated that compound 3 catalyzed hydrosilylation of carbonyls, alkenes, and alkyne with triethylsilane (HSiEt 3 ) under solvent‐free conditions. We found that catalyst 3 is also effective for large‐scale hydrosilylation reactions. Additionally, we have shown that compound 3 catalyzed benzaldehyde's intermolecular chemoselective hydrosilylation over other reducible functional groups.