Copper-Catalyzed Synthesis of 1,2-Disubstituted Cyclopentanes from 1,6-Dienes by Ring-Closing Kharasch Addition of Carbon Tetrachloride

The reaction of carbon tetrachloride (CCl4) with various 1,6-heptadienes catalyzed by copper homoscorpionate complexes affords cyclization products in moderate to high yields. The process involves the addition of the trichloromethyl radical to the diene followed by a 5-exo-trig cyclization reaction, resulting in the formation of the cis-3-chloromethyl-4-(2,2,2-trichloroethyl)cyclopentane isomers in a highly regiospecific and stereospecific manner. We have studied the use of magnesium (Mg) as reducing agent for the regeneration of copper(I) catalysts. This method has afforded heterocycles in high yields even in the cases of diallyl ether (DAE) and tert-butyl NN-diallylcarbamate (TBDAC).