A convergent route to substituted azetidines and to Boc-protected 4-aminomethylpyrroles

The radical addition of xanthates to Boc-protected azetine gives adducts, which can be reductively dexanthylated to furnish variously substituted azetidines. In the case of α-xanthyl ketones, treatment of the initial adducts with ammonia or primary amines, furnishes 2,4-disubstituted, 2,3,4-trisubstituted, and polycyclic pyrroles having a protected aminomethyl group at position-4. An unusual ring opening was observed in the case of a cyclobutanone precursor. It also proved possible to add an azetidinyl radical to an indole ring. Most of these products would be very difficult to obtain by more conventional routes.