Trimethylsilyl thiane

Free intermediate thioaldehydes 598 or 602 and the selenoaldehydes 605 and HMDSO 7 are obtained in THF at 0°C on treatment of aliphatic and aromatic aldehydes with bis(trimethylsilyl)thiane 601 or bis(trimethylsilyl)selenide 604 in the presence of traces of butyllithium, while trapping the sensitive intermediate thio- or selenoaldehydes 602 and 605 with cyclopentadiene or cyclohexadiene to furnish mixtures of endo and exo Diels-Alder adducts such as 603 a and 606 a and 603 b and 603 b [148-150], the exo/endo ratio of which can be controlled [150] (Scheme 5.48). Analogous reaction of ketones such as 2-adamantanone or acetylene ketones with MesSiXSiMes 608 (a. X=S (601) b. X=Se (604)) in the presence of... 

CoCl2 6H20 [149] or TMSOTf 20 [150-152] in acetonitrile afford Diels-Alder adducts in yields of up to 85%. The dienals 607 are converted by bis(trimethyl-silyl)thiane 601 or bis(trimethylsilyl)selenide 604 and catalytic amounts of BuLi, via 609, to the intramolecular Diels-Alder products 610 in up to 70% yield [153, 154]. 

The chemistry of rran5-4-r-butyl(diphenyl)silyloxythiane oxide has been investigated by Simpkins in the synthesis of protected, substituted secondary alcohols. Simpkins has found that the anion of fra s-4-r-butyl(diphenyl) silyloxythiane oxide, when treated with trimethylsilyl chloride, can form a 2,4-disubstituted thiane in turn, this product may be easily desulfurized with Raney nickel to liberate (S)-3-r-butyl(diphenyl)silyloxy-l-trimethylsilylpentane in good yield (Scheme 4.49) [101]. 

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