Electrochemical reactions. Part 23. Intramolecular radical substitution during the reduction of 2-halogeno-N-methyl-N-naphthylbenzamides

Abstract

Phenyl radical intermediates formed by the reductive cleavage of the carbon-halogen bond in 2-halogeno-N-methyl-N-(1-naphthyl)benzamides undergo intramolecular substitution to give N-methyl-2-(1-naphthyl)benzamide, and no N-methylbenzo[c]phenanthridone is formed. Reduction of 2-halogeno-N-methyl-N-(2-naphthyl)benzamides gives N-methyl-2-(2-naphthyl)benzamide, N-methylbenzo[a]phenanthridone, and N-methylbenzo[b]phenanthridone. These results complete our comparison of this electrochemical reaction with related radical Pschorr cyclisations. Further reduction of these initial reaction products occurs so that only qualitative conclusions can be drawn from the product yields.