Despite the fact that the hydrosilylation reaction has been known for decades, this widely used synthetic tool still throws up interesting challenges and opportunities. Our use of Karstedt's catalyst to study of the reduction of DMF (Me2NCHO) by the popular �dual SiH� containing tetramethyldisiloxane, HMe2SiOSiMe2H, 1 , has revealed that the first step in the process involves a single initial hydrosilylation to form HSiMe2OSiMe2OCH2NMe2, 2 . This intermediate is readily isolated and purified via distillation at 500C/15mm Hg; In the presence of a series of transition metal catalysts, including Karstedt's, this material readily transforms to trimethylamine, Me3N, and a transient material that we propose is (Me2SiO)2, D2, that itself transforms to (Me2SiO)n , n = 4, D4, and n =6, D6. The result demonstrates that the �dual SiH� effect may come about by virtue of the facile intramolecular elimination of the amine Me3N from 1,  indicating that a single molecule of 1  effectively reduces the amide rather than 2 for the monosilanes. Despite this reactivity 2  can also be used to perform the expected metal-catalysed hydrosilylation chemistry of the SiH group as well as reactions of the SiOCH2NMe2 functionality involving siloxane chain extension.

Transition metal catalyzed activation of the SiH bond: New insights into the dual SiH effect

247th National Meeting (2014)

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