Reaction of (α,β‐Epoxyalkyl)silanes with α‐Sulfonyl Anions and α‐Sulfonyl Anions in the Presence of a Lewis Acid. A Method for the Synthesis of ( Z )‐ sec ‐Allylic Alcohols and β,γ‐Unsaturated Alkyl Phenyl Sulfones

The reaction of 2‐alkyl‐3‐(trimethylsilyl)oxiranes ( la or 1b ) with anions generated from alkyl phenyl sulfones ( 2a‐f ) followed by hydrolysis affords sec ‐allyl alcohols 3 – 7. An analogous reaction in the presence of BF 3 · Et 2 O affords adducts 8 – 11. Treatment of 8 – 11 with NaOH under phase‐transfer conditions affords stereospecifically the corresponding allylic alcohols 4a – 5c. Reaction of oxirane 1a with anions derived from sterically hindered sulfones 2e or 2f in the presence of BF 3 · Et 2 O was investigated. Reaction of compounds 8 , 9 with phosphorus tribromide in pyridine affords β,γ‐unsaturated sulfones 19 .