Stereoselective Alkylidenation of Ketones with 2-(<i>p</i>-Toluenesulfinyl)benzyl Iodide: Synthesis of Enantiomerically Pure Trisubstituted Epoxides

Alkylidenation of arylmethyl, dialkyl, and cyclic ketones with 2-(p-toluenesulfinyl)benzyl iodide in the presence of NaN(SiMe3)2 takes place with a high or complete control of the facial selectivity at the carbonyl group (up to 98% de) and the carbanion (>98% de), respectively, yielding mixtures of only two optically pure trisubstituted epoxides (E/Z ratio ranges between 2:1 and >50:1). Removal of the p-tolylsulfinyl group with t-BuLi provides the corresponding (E)-3-phenyl-2,2-disubstituted epoxides without affecting their optical purity.