Conjugate Addition of Diethyl 1‑Fluoro-1-phenylsulfonylmethanephosphonate to α,β-Unsaturated Compounds

Diethyl
1-fluoro-1-phenylsulfonylmethanephosphonate (1) in the
presence of cesium carbonate undergoes efficient 1,4-addition
to Michael acceptors having terminal double bonds such as α,β-unsaturated
ketones, esters, sulfones, sulfoxides, and phosphonates to yield the
corresponding adducts in good to excellent yields. In the presence
of sodium hydride, 1 reacts with α,β-enones
to provide γ-fluoro-γ-phenylsulfonylenol phosphates arising
from 1,4-addition followed by phosphonate to phosphate rearrangement.