STRUCTURE DETERMINATION OF THE PRODUCTS FROM THE ACID-CATALYZED CONDENSATION OF INDOLE WITH ACETONE

Four of the previously reported compounds obtained from the acid-catal yzed condensation of indole with acetone are now assigned the followin g structures: ahydro-2-(1H-indol-3-yl)-4,4-dimethyl-3H-carbazole (2a), 1,1',4,4'-tetrahydro-1,1,1',1'-tetramethyl-3, 3'(2H,2'H)-spirobi[cycl opent[b]indole] (4), 4,4a-dihydro-2-(3-1H-indolyl)-4,4-dimeth (7), and etrahydro-1,1,4,4-tetramethylcyclopent[kl]acridine (8). The structure of the novel rearrangement product 8 was solved by an X-ray crystal s tructure determination. The two previously reported autoxidation produ cts of 4 are now assigned the following structures: 1,3',4,4'-tetrahyd ro-1, 1,4',4'-tetramethyl-cis-dispiro [cyclopent[b]indole-3(2H),2'(5'H )-furan-5',3 ''- [3H]-indol]2''(1''H)-one (5) and 3(2H),3'(4'H)-1-benz azocine]-2'(1'H),6'(5'H)-dione (6).