Bis methylthio trimethylsilyl methane

Preparative Methods prepared from lithiobis(methylthio)-methane by silylation with chlorotrimethylsilane (eq 1). Both bis(methylthio)methane and chlorotrimethylsilane are commercially available. 

A list of General Abbreviations appears on the front Endpapers 

Lithiobis(methylthio)(trimethylsilyl)methane. The anion is generated by treatment of the title compound with -butyllithium in THF at — 60°C (eq 2). This species is well-behaved at low temperature. Useful reactions of this anion are discussed in the following sections. 

Reaction of the lithio species with a-oxo ketones and aldehydes allows the formation of 8, 8-disubstituted enones, useful intermediates for the preparation of unsaturated 1,5-diketones (eq 5).  

Acyl Anion Conjugate Additions. The lithio reagent readily undergoes 1,4-addition to unsaturated substrates (eq 6), in direct contrast to the corresponding 2-lithio-2-trimethylsilyl-l,3-dithiane, which is a poor Michael donor. The initial Michael adducts can also be alkylated to provide highly functionalized products. Very good levels of diastereoselectivity have been observed in the 1,4-addition and enolate alkylations of cyclic enoates (eq 7)2 and acyclic enones (eq 8).  

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I his reagent is prepared from bis(methylthio)(trimethylsilyl) methane. 

Lithiated bis(methylthio)(trimethylsilyl)methane undergoes a Michael addition with cyclohept-2-enone to give (309) after hydrolysis. 4-Chloro-2,6-bis(methylthio) thiopyrylium perchlorate condenses with P-diketones in the presence of triethylamine to give thiopyranylidene derivatives, e.g. cycloheptane-1,3-dione gave (310). ... 

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