Addition reactions of heterocyclic compounds. Part 66. The 13C nuclear magnetic resonance spectra and structures of adducts from 2-alkylquinolines and other heterocycles possessing activated 2-substituents with dialkyl acetylenedicarboxylates

Abstract

The ¹³C n.m.r. spectrum for tetramethyl 3-bromo-7a,8,9,9a-tetrahydrocyclobuta[4,5]pyrrolo[1,2-a]quinoline-7,r-7a,t-9,c-9a-tetracarboxylate, obtained from 6-bromo-2-methylquinoline, has been compared with those of compounds formed both from quinolines and from a variety of nitrogen-containing heterocycles with similarly activated alkyl groups. The presence of the postulated azepine rings in some of these compounds has been confirmed, but in the majority the seven-membered ring previously suggested is actually a cyclobutapyrrole system. Spectral differences between the azepine and cyclobutapyrrole types are summarised.