Synthesis of representative 10‐aryl‐, 10‐aralkyl‐ and 10‐heteraryl‐9H‐naphtho[1′,2′:4,5]thiazolo[3,2‐b]‐ [1,2,4]triazin‐9‐ones as potential anti‐HIV agents

Abstract

AbstractTo prepare the title compounds, cyclocondensation of 1‐amino‐2‐iminonaphtho[1,2‐d]thiazole (2) with some representative glyoxylic acid derivatives was investigated. Heating 2 with methyl phenylglyoxylate (3a) in methanol afforded only the open chain intermediates 4a,b. However, when this reaction was performed in re‐fluxing glacial acetic acid, the expected compound, 10‐phenyl‐9H‐naphtho[1′,2′:4,5]thiazolo[3,2‐b][1,2,4]‐ triazin‐9‐one (5a) was produced in 27% yield. Similar treatment of 2 with benzyl‐, 2‐furyl‐ and 2‐thienylgly‐oxylic acids 3b‐d gave the corresponding 10‐benzyl‐, 10‐(2‐furyl)‐ and 10‐(2‐thienyl)‐9H‐naphtho[1′,2′:4,5]thi‐azolo[3,2‐b][1,2,4]triazin‐9‐ones 5b‐d in 48–67% yields. As by‐products, 9‐benzoyl‐ and 9‐(2‐thenoyl)naphtho‐[1′,2′:4,5]thiazolo[3,2‐b][1,2,4]triazoles 6a,d were also isolated. Compound 5a was selected for in vitro anti‐HIV evaluation but found to be inactive.