Triprenylstannyl radical or benzenethiyl radical promotedtransformation of 1,1-dialk oxycarronyl-2-(1,3-butadienyl)cyclopropanes into 2-ethenyl-3-cyclopentenes

Dimethyl 2-(1,3-butadienyl)cyclopropane-1,1-dicarboxylate reacts with catalytic amount of Ph3SnH in benzene at 80°C to provide dimethyl 2-ethenyl-3-cyclopentene-1,1-dicarboxylate in good yield. The transformation of N-tosyl-2-(1,3-butadienyl)aziridine into N-tosyl-2-vinyl-3-pyrroline is also described.