BEHAVIOR OF 2-CARBOMETHOXY- AND 2-ACETYL-1,4-BENZOQUINONE IN NENITZESCU INDOLE SYNTHESIS

Reaction of 2-carbomethoxy-1,4-benzoquinone (1) with ethyl 3-aminocrotonate (2a) gave ethyl trans-3-amino- 2-(2-carbomethoxy-3,6-dihydroxyphenyl)crotonate (3). This Michael-type adduct was transformed into ethyl 4-carbomethoxy-5-hydroxy-2-methylindole-3-carboxylate (4) and ethyl 5,8-dihydroxy-3-methylisocarbostyril- 4-carboxylate (5) when treated with 1 under equilibrating conditions. 2-Acetyl-1,4-benzoquinone (8) reacted with 2a and t-butyl 3-aminocrotonate (2b) to give the ethyl (9a) and t-butyl (9b) esters, respectively, of 5,8-dihydroxy-1,3-dimethylisoquinoline-4-carboxylic acid. © 1968, American Chemical Society. All rights reserved.