Cyclization of 2,4‐dinitronaphth‐1‐yl amino acids and their analogues to naphthimindazol‐N‐oxides: Kinetics and mechanism

Abstract

AbstractA variety of novel naphthimindazol‐N‐oxides and naphththiazol‐N‐oxide have been prepared in a simple two‐step process. The first step involves the reaction of 1‐chloro‐2,4‐dinitronaphthalene with glycine, alanine, glycolic acid, thioglycolic acid, and their methyl esters affording substitution products, the subsequent treatment of which with base furnishes naphthimindazol‐N‐oxide and naphththiazol‐N‐oxide derivatives. Stepwise reaction mechanisms via carbanions, nitrogen anions, and spiro Meisenheimer intermediates are proposed. The action of 10% NaOH in dioxane on the substitution products was measured spectrophotochemically, and the kinetic studies suggested that the N‐naphthyl glycine and N‐naphthyl alanine follow a second‐order rate law while S‐naphthyl thioglycolic acid is accurately first‐order kinetics.