Photoinduced Cyclizations of Mono- and Dianions of N-Acyl-o-chloroanilines and N-Acyl-o-chlorobenzylamines as General Methods for the Synthesis of Oxindoles and 1,4-Dihydro-3(2H)-isoquinolinones

Article abstract of DOI:10.1021/ja00288a027

Formation of the monoanions of a series of N-acyl-N-alkyl-o-chloroanilines by means of LDA in THF followed by irradiation with near-UV light affords 1,3-dialkyloxindoles in good yields.Similar photoinduced cyclizations of dianions derived from N-acyl-o-chloroanilines leads to 3-alkyloxindoles.Photocyclizations of mono- and dianion prepared from α,β-unsaturated o-haloanilides proceed to form 3-alkylideneoxindoles.Carbanions derived from N-acyl-o-chlorobenzylamines also undergo photoassisted ring closure to afford 1,4-dihydro-3(2H)-isoquinolinones.The influence of near-UV light and the effect of inhibitors implicate a radical-chain mechanism as the major reaction pathway in this convenient new method for oxindole and isoquinolinone synthesis.