Silylenes enolizable ketones

Products of the type (24) also result from enolizable ketones without the formation of silyl enol ethers if the reaction is carried out in the presence of tertiary phosphines. The proposed mechanism involves the betaine R3P—SiMe2 as the silylene transfer agent. In preventing a 1,3-hydrogen migration, the phosphine may well induce dimerization prior to oxasilacyclopropane formation. The dioxadisilacyclohexane (24) can be reduced with LiAIHU to give dimethylsilyl-substituted carbinols, so the reaction is of synthetic value (Scheme 34) (78JA7074). 

Photochemically generated silylenes react with enolizable ketones to give silyl enol ethers. Irradiation of 20 with a low-pressure mercury lamp in the presence of acetone, diethyl ketone, or cyclohexanone gives the re-... 

Enolizable ketones can be silylated using ReSia and HMPT in the presence of catalytic amounts of sodium, while 1,2-disilacyclobutenes will ring expand with oxygen, silylenes, acetylenes, and Fe2(CO)8 (Scheme 18). The Grignard reagent... 

This preparative method can be applied to the synthesis of various silylene and germylene complexes this nonphotochemi-cal method is especially useful for the synthesis of light-sensitive complexes. ( 7 -C5Me4Et)(OC)(H)Ru=Si(H)[C(SiMe3)3] was also synthesized by this method (1). Cp (OC)(H)Ru=Si(H)[C(SiMe3)3] underwent C—C bond activation of nitriles (1), a-hydrogen abstraction of enolizable ketones (4), hydrosilylation of non-enolizable ketones (4), isocyanates (5), and C=S bond cleavage of isothiocyanates (5). 

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