LEWIS ACID-PROMOTED REACTIONS OF STYRENYL SYSTEMS WITH BENZOQUINONE BISIMINES - NEW REGIOSELECTIVE SYNTHESES OF SUBSTITUTED 2-ARYL-2,3-DIHYDROINDOLES AND 2-ARYLINDOLES

BF3-promoted reactions of (N-benzoyl)-4-(N-benzenesulfonyl)-1,4-benzoq uinone bisimines (2/3) with beta-methylstyrenes yield amino)-6-alkoxy- 2-aryl-3-methyl-2,3-dihydroindoles (4/5) or -6-aryl-7-methyl-4,8-dioxo bicyclo[3.2.1]oct-2-enes (6) regio- and stereoselectively. The former are produced in reactions with styrenes bearing alkoxy substituents, w hereas with neutral or electron deficient styrenes, the latter are fou nd. As applications of this new methodology to the synthesis of biolog ically interesting molecules, reactions of 2H-chromenes and 7-methoxy- N-toluenesulfonyl-1,2-dihydroquinoline with the bisimines have been de veloped as routes to substituted aza- and diazapterocarpans. Syntheses of 2-arylindoles via oxidation of the dihydroindoles 4 are also repor ted.