Rhodium-Catalyzed O–H Insertion Reactions to (2-Diazo-1,1,3,3,3-pentafluoropropyl)phosphonate: A Convenient Route to Fluorinated β-Alkoxy Vinylphosphonates

The rhodium(II)-catalyzed insertion of benzyl and alkyl alcohols with 2-diazo-1,1,3,3,3-pentafluoropropylphosphonate unexpectedly afforded fluorinated β-alkoxy vinylphosphonates. The reaction proceeds under mild conditions and shows broad substrate scope. Twenty-four new derivatives were synthesized in moderate to excellent yields with excellent diastereoselectivity (up to 99%). DFT calculations support the proposed mechanism where <i>Z</i>-isomers consistently predominate over <i>E</i>-isomers. For selected tertiary, benzylic, allylic, and acidic alcohols, however, diethyl (1,3,3,3-tetrafluoro-2,2-dihydroxypropyl)phosphonate was obtained as the major product, instead of vinyl phosphonate.