Pyrroloindoles. 14. Synthesis of dimethyl substituted pyrrolo[2,3-e]indole, indolo[4,5-e]indole, and some ditetrahydrocarbazolocarbazoles
Cyclization of the m-phenylen- and 2,7-naphthylendihydrazones of acetone leads to formation of dimethyl substituted, angular pyrrolo- and indolo-indoles. Cyclization of the 2,7-naphthylendihydrazone of cyclohexanone gives the linear 1H,12H-2,3,4,5,8,9,10,11-octahydrocarbazolo[3,4-d]carbazole. A further impurity of an angular ditetrahydrocarbazolocarbazole is also formed.