3-Substituted Blatter Radicals: Cyclization of N-Arylguanidines and N-Arylamidines to Benzo[e][1,2,4]triazines and PhLi Addition

Abstract

A series of 3-amino- and 3-alkyl-substituted 1-phenyl-1,4-dihydrobenzo[e][1,2,4]triazin-4-yls was prepared in four steps involving N-arylation, cyclization of N-arylguanidines and N-arylamidines, reduction of the resulting N-oxides to benzo[e][1,2,4]triazines, and subsequent addition of PhLi followed by aerial oxidation. The resulting seven C(3)-substituted benzo[e][1,2,4]triazin-4-yls were analyzed by spectroscopic and electrochemical methods augmented with density functional theory (DFT) methods. Electrochemical data were compared to DFT results and correlated with substituent parameters.