Silanones reactions with carbonyl compounds

All known silenes react violently with molecular oxygen with the exception of the stable 1-silaallenes which are air-stable. Along with carbonyl compounds the products of the oxidation of silenes are cyclic siloxanes from the corresponding silanone, depending on the reaction conditions3,8,28. For example, when the stable adamantylsilene 150 is... 

Reactions of silylenes with unsaturated organic substrates are valuable for the synthesis of novel silicon compounds (1,2). Over the past three decades, the reactions of silylenes with carbonyl compounds have been extensively investigated (3—5). It has been shown that these reactions produce diverse types of products via siloxirane or carbonyl silaylide intermediates while the carbonyl C—O a bond is generally maintained (3—5). Complete cleavage of the C—O bond has only been observed in several cases (4). Furthermore, the synthesis and physical properties of siloles and related unsaturated carbon—silicon heterocycles are of great interest as heteroaromatic molecular precursors and potential molecular optical materials (6). In this experiment, reaction of a NHC-stabilized silacyclopentadienylidene (silole silylene) with aldehydes, leading to the formation of the novel NHC-stabilized a,(3-unsaturated silanone, was described. 

Some remarkable chemistry is observed when silenes react with heteroatom systems, in particular carbonyl compounds (]>C=0) and imines Q>C=N—R). The reaction with ketones was first described by Sommer (203), who postulated formation of an intermediate siloxetane which could not be observed and hence was considered to be unstable even at room temperature, decomposing spontaneously to a silanone (normally isolated as its trimer and other oligomers) and the observed alkene [Eq. (14)]. Many efforts have been made to demonstrate the existence of the siloxetane, but it is only very recently that claims have been advanced for the isolation of this species. In one case (86) an alternative formulation for the product obtained has been advanced (204). In a second case (121) involving reaction of a highly hindered silene with cyclopentadienones,... 

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