Epoxides of Bicyclic Phospholane Derivatives. Stereochemistry of Epoxidation of 2- and 3-Phospholene Oxides

Article abstract of DOI:10.1021/jo01311a029

3-Phospholene oxides fused at the b or c faces to cyclohexano or cyclopentano rings were smoothly epoxidized by m-chloroperbenzoic acid in a stereospecific manner. 2-Phospholene oxides joined to cycloalkano groups at the b face were also easily epoxidized, again with stereospecificity, but with the opposite orientation of incoming oxygen relative to the phosphoryl oxygen.This was determined by converting epoxides of each type in the 1-methylperhydrophosphindole 1-oxide system to a common structure (1-methyl-3a-hydroxyperhydrophosphindole 1-oxide) which, however, had different stereochemical features. 13C NMR evidence was gathered to support an earlier suggestion that epoxidation of 1-substituted 3-phospholene 1-oxides occurs anti to the phosphoryl oxygen.Several epoxyphospholane oxides were deoxygenated to give the first examples of epoxyphosphines, and from them were formed 1,1-dibromides, 1-sulfides, and methiodides.The epoxy ring from a bicyclic 2-phospholene oxide gave an amino alcohol from attack at the α-position by cyclohexylamine; the epoxide from the isomeric 3-phospholene oxide was rearranged to the allylic alcohol under the same conditions or with triethylamine or Li-ethylenediamine, although pyrrolidine did give some amino alcohol by attack at the 3-position.