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P-heterocyclic γ-ketophosphonateswere synthesized by the Michael reaction of methyl vinyl ketone with dibenzo-1,2-oxaphosphorine 2-oxide, 1,3,2-dioxaphosphorine 2-oxide and benzo-1,3,2-dioxaphospholane 2-oxide, respectively. In the first two cases, 50% of 1,8-diazabicyclo[5.4.0]undec-7-ene had to be used that was also required in the addition of dibenzooxaphosphorine oxide to cyclohexenone to result in the formation of the corresponding γ-ketophosphonate. The addition of dibenzooxaphosphorine oxide to less reactive 1,2-dihydrophosphinine oxide was accomplished after activation by an equimolar amount of trimethylaluminum to afford a 3-P(O)<-1,2,3,6-tetrahydrophosphinine oxide, which was subjected to catalytic hydrogenation to provide the corresponding 1,2,3,4,5,6-hexahydrophosphinine oxide.

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