σ-Complexes as biochemical probes. Part 1. σ-Complex formation by 7-methoxy-4-nitrobenzofurazan 1-oxide

Abstract

The reaction of 7-methoxy-4-nitrobenzofurazan 1-oxide with methoxide ion in dimethyl sulphoxide–methanol (or in dimethyl sulphoxide–methanol–chloroform) gives rise to a kinetically controlled C-5 adduct and a thermo-dynamically controlled C-7 adduct. Some unusual features in the n.m.r. spectra are discussed.