Direct synthesis of isoxazolidinylphosphines by cycloaddition of nitrones to diphenylphosphinoethenes and x-ray structure of 7,7-dimethyl-1-oxo-1-phenyl-3-diphenylphosphinyl-hexahydro-1H-pyrrolo [1,2-c] [1,3,2] oxazaphosphorine

Abstract

The 1,3-dipolar cycloaddition reaction of N-alkyl nitrones with diphenylvinylphosphines affords directly isoxazolidinylphosphines in satisfactory yields and in regio- and stereoselective manner. The parent diphenylvinylphosphine was found to favor the formation of 5-phosphinoisoxazolidines whereas diphenylpropenylphosphine gave instead the 4-phosphinoisoxazolidine regioisomer. However, in reactions utilizing on alkylarylvinylphosphine and/or N-arylnitrone, oxidation of the phosphine by the nitrone reagent was found to precede the cycloaddition. An attempted conversion of the bicyclic isoxazolidine derived from 2,2-dimethyl-dihydro-2H-pyrrole 1-oxide and diphenylvinylphosphine to the perhydropyrrolo[1,2-c] [1,3,2]oxaza-phosphorine ring system was accomplished through the use of the corresponding phosphine oxide derivative and provided a single diastereoisomer of the desired pyrrolooxazaphosphorinane characterized ultimately in the form of its dioxide hydrate by the X-ray diffraction technique.