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Ligand-Controlled Remarkable Regio- and Stereodivergence in Intermolecular Hydrosilylation of Internal Alkynes: Experimental and Theoretical Studies

2013; American Chemical Society; Volume: 135; Issue: 37 Linguagem: Inglês

10.1021/ja405752w

1943-2984

Shengtao Ding, Lijuan Song, Lung Wa Chung, Xinhao Zhang, Jianwei Sun, Yun‐Dong Wu,

Asymmetric Synthesis and Catalysis

The first highly efficient ligand-controlled regio- and stereodivergent intermolecular hydrosilylations of internal alkynes have been disclosed. Cationic ruthenium complexes [Cp*Ru(MeCN)3]+ and [CpRu(MeCN)3]+ have been demonstrated to catalyze intermolecular hydrosilylations of silyl alkynes to form a range of vinyldisilanes with excellent but opposite regio- and stereoselectivity, with the former being α anti addition and the latter β syn addition. The use of a silyl masking group not only provides sufficient steric bulk for high selectivity but also leads to versatile product derivatizations toward a variety of useful building blocks. DFT calculations suggest that the reactions proceed by a mechanism that involves oxidative hydrometalation, isomerization, and reductive silyl migration. The energetics of the transition states and intermediates varies dramatically with the catalyst ligand (Cp* and Cp). Theoretical studies combined with experimental evidence confirm that steric effect plays a critical role in governing the regio- and stereoselectivity, and the interplay between the substituent in the alkyne (e.g., silyl group) and the ligand ultimately determines the observed remarkable regio- and stereodivergence.