Tert-Butyldimethylchlorosilane

The simplest example of such a system is depicted in Eq. (5.28). The lithium enolate of 2-(trimethylsilyl)cyclopropanone is formed by the reaction of [l-(tri-methylsilyl)vinyl]lithium with carbon monoxide (Eq. (5.29)). Treatment of the vi-nyllithium with CO, at atmospheric pressure, in THF at 15 C for 2 h followed by quenching with trimethylchlorosilane at -78 "C afforded a somewhat labile product, which decomposed during the usual hydrolytic work-up. Quenching with tert-butyldimethylchlorosilane/HMPA instead allowed isolation of the products. The major product was a silylated cyclopropane enolate. It is noteworthy that the overall sequence follows a formal [2-1-1 jcycloaddition (Eq. (5.28)). The silylated alle-nolate was also formed as a by-product as the result of a 1,2-anionic silicon rearrangement. 

N- 0 anionic rearrangement has also been observed in monosilylhydroxylamines, and the results of derivatization experiments provide good evidence for equilibrium between N and O anions (2). For instance, lithiation of 0-trimethylsilylhydroxylamine followed by reaction with tert-butyldimethylchlorosilane produces a 3 1 mixture of rearranged and unrearranged products 23). 

Thiol and Disulfide Synthesis. Reaction of 2-tetrahydrofu-ranyl(thiomethyl)lithium with tert-butyldimethylchlorosilane, followed by n-BuLi and a second equivalent of t-butyldimethyl-chlorosilane followed by hydrolysis of the adduct with sil-ver(I) nitrate or mercury(II) chloride followed hy hydrogen sulfide or hydrogen chloride gives bis(f-butyldimethylsilyl)-methanethiol (t-BuMe2Si)2CHSH 91%) (eq 1). ... 

DBU proved to be an effective and selective catalyst for the tert-butyldimethylsilylation of primary and secondary alcohols at ambient temperature in different solvents in the presence of DBU (85BCJ3669). It is assumed that DBU forms a complex 602 with tcrt-butyldimethylchlorosilane, which subsequently reacts with alcohols. The fcrt-butyldimethylsilylation of the tertiary hydroxy group did not occur after even a prolonged reaction time. When 2-ethyl-l,3-hexanediol, 1,3-butanediol, and 1-phenyl-1,2-ethanediol were reacted, the corresponding primary silyl ether was obtained almost exclusively. 

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