Study On Cycloaddition Reaction Involved By 3-alkenyl Indole

Indole is an electron-rich heterocyclic arenes and is also a special alkaloid.Indole and its derivatives widely exist in many natural products and medicines in nature.The special chemical properties and biological activities of indole have won much attention from many chemists and pharmacologists to study indole-related topics.In this paper,we investigated some[3+2],[4+2],[4+3]cycloaddition reactions of 3-alkenylindole for synthesis pf various indole-containing polycyclic derivatives.1.The acid-catalyzed[4+2]cycloaddition of 3-（indol-3-yl）maleimides with four different active C=C bond compounds for the formation of different pyrrolocarbazole derivatives was studied,and the products were,showing good substrate universality.When the reaction substrate is 3-alkyleneindolinone,The reaction exhibits excellent diastereoselectivity;When the reactant is 2-arylidene-1,3-indanediones,the reaction will gave by-product coming from[4+2]cycloaddition of 3-（indol-3-yl）maleimide itself;When the reactant is 4-arylidene-3pyrazolone and 5-methyl-2-phenylthiazol-4-one,the reaction only undergoes Michael addition to give chain product,which can be converted to carbazole derivatives by oxidation.It was found that different active C=C bond substrates show different reactivity.The structures of the sixty-six new products were characterized by IR,1H NMR,13C NMR and HRMS spectroscopy.The single structure of eighteen compounds were determined by X-ray diffiraction method.2.The acid-catalyzed[4+2]cycloaddition of 2-（indol-3-yl）naphthalene-1,4-dione with three different active C=C bond compounds was studied,and the naphthocarbazole derivativs were obtained Comparing with the similar reaction of 3-（indol-3-yl）maleimide,this reaction does not require an external oxidan and oxygen in the air can be use as efficient oxidizer.When 3-methyleneindolinones were employed in the reaction.the diastereoselectivity of the reaction can be adjusted by controlling the water content in the reaction system.Under anhydrous conditions,only one diastereomer can be selectively produced.The structures of the sixty-one new products were characterized by IR,1H NMR,13C NMR and HRMS spectroscopy.The single structure of nineteen compounds were determined by X-ray diffiraction method.3.Acid-catalyzed[3+2]and[4+3]cycloaddition reactions of 3-（indol-3-yl）maleimide with indole alcohol derivatives were studied.The reaction with（indol-2-yl）benzyl alcohol undergoes sequential Friedel-Crafts alkylation,Michael addition and carbocation rearrangement to afford cycloheptyl[b]indole derivatives.During the reaction,the maleimide structural unit is transferred from the 3-position to the 2-position of indole;When 3-hydroxy3-（indol-3-yl）indolin-2-one was used as substrates,the cyclopentyl[b]indole derivatives were selectively obtained as sole products;When thesubstrate was 2-hydroxy-2-（indole-3-yl）indene-1,3-dione,the reaction afforded cyclopentyl[b]indole derivatives as major product and cycloheptyl[b]indole derivative as minor product.The structures of the thirty-five new products were characterized by IR,1H NMR,13C NMR and HRMS spectroscopy.The single structure of seven compounds were determined by X-ray diffiraction method.