Tin(iv) chloride mediated (3 + 2) annulation of trans -2-aroyl-3-styrylcyclopropane-1,1-dicarboxylates with nitriles: diastereoselective access to 5-vinyl-1-pyrroline derivatives.

A tin(iv) chloride promoted (3 + 2) annulation of trans -2-aroyl-3-styrylcyclopropane-1,1-dicarboxylates with nitriles is reported. The transformation involves the Lewis acid assisted formation of 1,5-dipolar intermediates from the cyclopropane dicarboxylates and nitriles followed by cyclization. The reactions proceed in a highly diastereoselective manner and afford 5-vinyl-1-pyrroline derivatives in 60-88% yields.