Silanones from silanols

The platinum complex [ Pt(dmpe) 2( X-H)2](OTf)2 can catalyze the generation of silanones from secondary silanols under very mild conditions (at room tempera-... 

In the reaction of lithiated alkylbenzothiazoles with BTSP, the formation of methylated products always competes with the formation of silyl ethers. The demethylation of BTSP can tentatively be conceived as being derived from the nucleophilic attack of alkylben-zothiazole anion at the methyl group of BTSP with displacement of silanone and silanolate anion, while silyl ethers would form by nucleophilic attack of the alkylbenzothiazole anion at the oxygen of BTSP (Scheme 8/. ... 

Most recently, Milstein and coworkers reported a new type of homogeneous catalytic reaction that generates silanones from secondary silanols under extremely mild conditions. The platinum complex (dmpe)Pt(Me)OTf) (27) (dmpe = Me2PCH2CH2PMe2, OTf = OSO2CF3 was treated with an equimolar amount of the silanol, (i-PrhSilKOII) (28), in acetone to yield a new dimeric hydrido-bridged complex 29 and the trimer 30 of diisopropylsilanone, 31 (Scheme 12)29. 

Eabom and Stanczyk deduced from kinetic data that under basic conditions silanone 10 can be formed by loss of a proton and a carbanion R from the silanols 22 (R = m-CIC6H4CH2 or PhC=C) (Scheme 10)25. 

The generation of methane in the reaction was evidenced by the 111 NMR spectrum of the reaction mixture. It was also shown that the newly obtained complex 29 reacts catalytically with silanol 28 to give the trimer 30 (presumably from trimerization of 31) with the evolution of hydrogen gas. In the presence of MesSiOMe the same reaction resulted in the formation of an insertion product of the intermediate silanone 31 as shown in the lower part of Scheme 12. The proposed catalytic cycle for the dehydrogenation of 28 with 29 is shown in Scheme 13. It should be noted, however, that spectroscopic evidence for the proposed silanones was not presented. 

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