Electrosynthesis of 3-chloro-1,4-disubstituted-2(1H)- quinolinones and 3,3-dichloro-4-hydroxy-1,4-disubstituted- 3,4-dihydro-2(1H)-quinolinones, as well as a new convenient process to dioxindoles.
Cathodic reduction of N-(2-acyl(or aroyl)phenyl)-2,2,2,-trichloro-N-alkylacetamide at -1.2 V (vs SCE) under aprotic conditions yields 3-chloro-1,4-disubstituted-2(1H)-quinolinones (1) as the major product. When the reaction is carried out at -0.8 V (vs SCE), 3,3-dichloro-4-hydroxy-1,4-disubstituted-3,4-dihydro-2(1H)-quinolinones (2) and 1,4-disubstituted-1,4-dihydro-quinoline-2,3-dione (3) are formed. Ring contraction of 2 and 3 in aqueous sodium hydroxide resulted in the formation of 3-hydroxy-1,3-dihydroindol-2-ones (5). The most plausible reaction mechanisms are proposed.
Batanero
Belén
B
Department of Organic Chemistry, University of Alcalá, 28871 Alcalá de Henares, Madrid, Spain.
Barba
Fructuoso
F