The periodate oxidation of some Cycloalk[b]indoles and their N-methyl derivatives: Effect of ring size on the spectral and chemical properties of the resultant lactams

Abstract

The sodium periodate oxidation of several cycloalk[b]indoles and their N-methyl derivatives gave a series of lactams, the ring size of which varied from 8 to 11 members. The effect of ring size on the spectral (ultraviolet, infrared and proton magnetic resonance) properties of these lactams and on their behaviour towards alkali (the Camps reaction), acid and heat is discussed.

Oxidation of 1,2,3-trimethylindole with periodate gave N-methyl-o-acetamidoacetophenone which exists in solution as a mixture of the exo and endo conformers. Solvent shift [δl(CDCl₃) - δ(C₆H₆)] data were useful in assigning structures not only to these conformers but also to the conformers of several related N-methyl-o-substituted acetanilides.

The ultraviolet and proton magnetic resonance spectra (including solvent shift data) of several related quinol-2(1H)- and -4(1H)-ones (obtained by the alkaline treatment of the above lactams) are discussed.