Treatment of 1-methyl-2-methylene-1-cyclohexyl hydroperoxide with a mixture of FeSO4/CuCl2 yielded 1-(1-chlorocyclohexyl)ethanone as the major product consistent with 6-endo-trig cyclization of the intermediate 5-acetylhex-5-enyl radical. This strategy was extended to the ring enlargement of a series of 1-isopropenylcycloalkyl hydroperoxides. Regioselective 7- or 8-endo-trig cyclization reactions could be achieved by treatment of the corresponding cyclopentyl or cyclohexyl hydroperoxides with either a mixture of FeSO4/CuCl2 or with FeSO4 only. The influence of substituents on the efficiency of the 8-endo-trig cyclization process was also explored. © 2003 Published by Elsevier Science Ltd.
- Allylic hydroperoxide
- endo-trig radical cyclization
- Iron(II) sulfate
- Ring enlargement