Reissert compound chemistry. Part IV. N-acyl pseudo-base formation and stereochemistry

Abstract

The formation is reported of a series of heterocyclic N-acyl pseudo-bases from 5-nitroisoquinoline, 3-methyl-5-nitroisoquinoline, and 6-nitroquinoline. The compounds were obtained under conditions for Reissert compound formation, only small yields of the latter being present in most cases. The N-acyl pseudo-bases appear to be covalent in character, and do not, in general, display tautomerism with an open chain or ionic form, in contrast to N-alkyl pseudo-bases. Long-range coupling observed in the n.m.r. of the N-acyl pseudo-bases and 1,2-dihydroisoquinolines and -quinolines of the Reissert type suggests the stereochemistry to be such that the substituent at the saturated carbon is adopting a quasi-axial position, analogous to substituted 1,2-dihydronaphthalenes. Characteristic resonance frequencies are indicated.