[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.
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.
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).
Raymond S. Gross
Marion Merrell Dow Research Institute, Cincinnati, OH, USA