Radical Domino Cyclizations For The Synthesis Of Phosphinoindoline Oxide And Quinolin-2-one Derivatives

In recent years,controlled radical reactions have unique advantages in the construction of molecular scaffolds containing quaternary carbon centers.Therefore,it has become one of the research goals of many chemists.Among them,the radical domino cyclization reactions provide a reliable and useful synthetic strategy for the constructing cyclic molecules.Therefore,it has received extensive attention.In this paper,in-situ-generated P-radicals were converted into phosphorus oxide derivatives and different C-radicals were transformed substituted quinolin-2-one derivatives.A total of 95 example of the target compounds were synthesized with good yields.The first part mainly introduced the characteristics of radical domino cyclization reactions and their current research progress.The domino cyclization reactions of P-radicals and C-radicals with o-arylalkynyl arylamines were highlighted.Meanwhile,the basis and innovation of this dissertation were described based on these report survey.The second part introduced the radical domino cyclization reaction of diphenylphosphine with o-arylalkynyl arylamines by combined DTBP and Mg（NO₃）₂·6H₂O,in which 27 examples of tribenzo[b,e,g]-phosphonium oxides in32%-88%yields were synthesized.By the control experiments,we found that the reaction can be compatible with both P-radicals and C-radicals,and both these radicals triggered cyclizations in turn,namely,P-radical induced cyclization is prior to C-radical transformation.When o-arylalkynyl arylamines have two different substituted aryl groups on the alkyne unit,the reaction features a high regioselectivity.The third section described the t-BuONO-mediated domino cyclization reaction of in-situ-generated 4-methoxyphenyl radicals with N-substituted 1,7-enynes,and a series of spiro[cyclohexa[2,5]diene-1,2’-cyclopenta[c]quinoline]-4,4’（5’H）-diones containing quaternary carbon centers were constructed,which successfully achieved bicyclization involving demethylation and dearomatization.This reaction gave 28 examples of the target compounds with moderate to good yields.Meanwhile,several control experiments indicated that the reaction process involved a radical mechanism was confirmed.The fourth part described radical domino cyclization reaction of N-substituted1,7-enynes with alkyl carboxylic acid by the combination with AgNO₃ and K₂S₂O₈ as catalytic oxidative system.This reaction was compatible with various substituted alkyl carboxylic acids,including benzo[b][1,4]dioxine-2-carboxylic acid,cyclopentyl carboxylic acid,cyclohexyl carboxylic acid,4-methylcyclohexyl carboxylic acid,cyclobutyl carboxylic acid,3-valproic acid,isopropyl acid and sec-butyric acid,which generated 40 examples of the target quinolin-2-one derivatives with different substituted patterns and good to excellent.This reaction further extended the synthetic application scope of radical bicyclization.