Lewis Acid-Promoted Reactions of Styrenyl Systems with Benzoquinone Bisimines: New Regioselective Syntheses of Substituted 2-Aryl-2,3-dihydroindoles and 2-Arylindoles
摘要:
BF3-promoted reactions of 2-alkoxy-1-(N-benzoyl)-4-(N-benzenesulfonyl)-1,4-benzoquinone bisimines (2/3) with beta-methylstyrenes yield trans-5-(N-benzoylamino)-6-alkoxy-2-aryl-3-methyl-2,3-dihydroindoles (4/5) or 3-(N-benzoylamino)-6-aryl-7-methyl-4,8-dioxobicyclo[3.2.1]oct-2-enes (6) regio- and stereoselectively. The former are produced in reactions with styrenes bearing alkoxy substituents, whereas with neutral or electron deficient styrenes, the latter are found. As applications of this new methodology to the synthesis of biologically interesting molecules, reactions of 2H-chromenes and 7-methoxy-N-toluenesulfonyl-1,2-dihydroquinoline with the bisimines have been developed as routes to substituted aza- and diazapterocarpans. Syntheses of 2-arylindoles via oxidation of the dihydroindoles 4 are also reported.
Cycloaddition reactions of 1,4-benzoquinone mono- and bisimides with styrenyl systems: New syntheses of nitrogen substituted azapterocarpans, pterocarpans, 2-aryl-2,3-dihydroindoles and -dihydrobenzofurans
作者:Thomas A. Engler、Kenneth O. Lynch、Wenying Chai、Steven P. Meduna
DOI:10.1016/0040-4039(95)00375-m
日期:1995.4
Lewisacid-promotedreactions of 1,4-benzoquinones and 1,4-benzoquinone bis- and monoimides with various 2H-chromenes, N-tosyl-1,2-dihydroquinolines and styrenes regio- and stereoselectively produce the title compounds in good yields.
Lewis Acid-Directed Reactions of Benzoquinone Mono-/Bis-imines: Application to Syntheses of Substituted β- and γ-Tetrahydrocarbolines
作者:Thomas A Engler、Jutta Wanner
DOI:10.1016/s0040-4039(97)01391-9
日期:1997.9
Ti(IV)-promoted reactions of N-phenylsulfonyl-3- and 4-piperidone enol ethers with 2-alkoxy-4-(N-phenylsulfonyl)imino-1,4-benzoquinone afford 8-alkoxy-7-hydroxy-tetrahydrocarbolines. However, reactions promoted by BF3 produce substituted benzofurans. Ti(IV)- or BF3-promoted reactions of 2-alkoxy-1-(N-benzoyl)-4-(N-phenylsulfonyl)-1,4-benzoquinone bisimines also afford substituted tetrahydrocarboline