[28872-77-7]  · C6H16SSi  · Trimethylsilylmethylenedimethylsulfurane  · (MW 148.38)

(vinyl sulfide preparation; preparation of silylcyclopropyl ketones from a,b-unsaturated ketones)

Physical Data: bp 46 °C/7 mmHg.

Analysis of Reagent Purity: 1H NMR.

Preparative Methods: from trimethylsilylmethyldimethylsulfonium iodide by treatment with n-Butyllithium in Et2O,1 s-Butyllithium in THF,2 or Potassium t-Butoxide in DMSO.3

Purification: distillation at reduced pressure or fractional condensation in a -45 °C trap.

Handling, Storage, and Precautions: undergoes thermal decomposition; best prepared in situ with s-BuLi.

General Discussion.

The addition of this ylide to a,b-unsaturated ketones affords silylcyclopropyl ketones in moderate yields (36-65%) (eq 1).2 The choice of conditions is very important as silylcyclopropanation is observed only with the reagent prepared in situ from trimethylsilylmethyldimethylsulfonium iodide and s-BuLi in THF.

Treatment of aryl or saturated ketones with trimethylsilylmethylenedimethylsulfurane affords vinyl sulfides (eq 2).2 The use of t-BuOK in DMSO leads to desilylation of the vinylsulfonium intermediate, giving a mixture of products depending upon the substrate used.3 The most predominant product results from elimination of trimethylsilanol followed by a 2,3-sigmatropic rearrangement of the allyl substituted sulfurane intermediate (eq 3).

1. McMullen, J. C.; Miller, N. E. IC 1970, 9, 2291.
2. Cooke, F.; Magnus, P.; Bundy, G. L. CC 1978, 714.
3. Fleischmann, C.; Zbiral, E. T 1978, 34, 317.

Raymond S. Gross

Marion Merrell Dow Research Institute, Cincinnati, OH, USA

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