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

Abstract

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.

Synthetic Organic Electrochemical Methods Since 2000: On the Verge of a Renaissance

“…712 Thus, one of the C–Cl bond was cathodically cleaved to generate a gem -dichloro carbanion species whereupon an ensuing aldol condensation gave the products. Similar processes were exploited in the preparation of 4-amino-2-aryl-2-oxazolines, 713 quinolinones, 714 and coumarins. 715 In another variant, the electrochemical reduction of trichloroacetates was applied to synthesize α -chloroepoxides (Figure 42J, bottom).…”

Intramolecular reductive cyclisations using electrochemistry: development of environmentally friendly synthetic methodologies

“…33,111,112 The electroreduction of trichloroacetamides with further intramolecular coupling with a carbonyl group has been reported for the synthesis of substituted quinolinones and dioxindoles. 113 Thus, the cathodic reduction of trichloro-N-methylacetamide 68 at À1.2 V vs. SCE afforded quinolinone 69 in 77% yield after reduction of the epoxide intermediate (Scheme 35).…”

Electrosynthesis of Halogenated δ‐Lactones

“…In earlier publications of our research group we described easy methodology to prepare heterocycles such as 3-chloro-4-alkyl(or aryl)-coumarins [1,2] or 1-alkyl-4-alkyl(or aryl)-3-chloroquinolinones [3] in good yield by electrochemical reduction of trichloroacetyl esters of o-hydroxyphenones or o-(N-alkyl)-aminophenones, respectively. After the first electron transfer, the electrogenerated radical-anion undergoes C-Cl cleavage to give a chlorine radical and an organic anion that is responsible for intramolecular addition to the carbonyl group.…”