ホスホン酸ジアルキルを用いる選択的官能基変換

概要

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Dialkyl phosphonate works as a reducing agent in the presence of triethylamine towards gem-dibromocyclopropanes and gem-dibromoolefins to give the corresponding monobromo derivatives, respectively. Reduction of gem-bromochlorocyclopropanes, 1, 1, 1-trichloromethane derivatives, 1, 1-dibromo-2-benzyloxyethylene, methyl α-bromocinnamate, α, p-dibromoacetophenone, and (1, 2-dibromoethyl) benzene is surveyed. Treatment of α-bromo- α, β-unsaturated carbonyl compounds or 1, 1-dibromo-2-trimethylsiloxycyclopropanes with dialkyl phosphonate and triethylamine affords, β, γ-unsaturated carbonyl compounds stereoselectively. This reductive deconjugation is applied to the syntheses of naturally occurring compounds, recifeiolide and pyrenophorin. Reductive phoshonation of gem-dibromocyclopropanes is performed by treatment with trialkyl phosphite-dialkyl phosphonate-triethylamine or trialkyl phosphite-triethylamine-water resulting in the formation of dialkyl cyclopropylphosphonates. The palladium-catalyzed reactions of aryl bromides or iodides with dialkyl phosphonates in the presence of triethylamine give the corresponding arylphosphonates. This method is extended to the stereospecific phosphonation of vinyl bromides.
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