A novel process for the reductive magnesiation of 2-substituted oxetanes and the metalative
cyclization of ω-alkynyl oxetanes is developed using n-propylmagnesium chloride in the presence of an iron catalyst. The generated intermediate
organomagnesium compounds react with electrophiles. The reactions of 2,3-disubstituted
oxetanes and their subsequent allylation with allyl halides in the presence or absence
of copper(I) cyanide as the catalyst is studied with a unique switching of stereoselectivity
being observed in the absence or presence of copper(I) cyanide . In addition, it is
found that the metalative cyclization of 3-substituted 2-alkynyl oxetanes proceeds
in an anti-selective manner starting from both syn- and anti-substrates. In all cases, the stereochemistry at the 2-position of the oxetanes is
lost during the reactions suggesting the involvement of a radical process.
Key words
iron catalyst - oxetanes - reductive magnesiation - metalative cyclization - (3-oxidopropyl)magnesium
- diastereoselective reaction