GENERAL AND EFFICIENT APPROACHES TO FUSED [1,2-ALPHA]PYRROLES AND [1,2-ALPHA]INDOLES

2-[(Benzotriazol-1-yl)methyl]pyrroles 4a-c, and 15a,b and -indoles 23, prepared as previously reported,(1,2) were converted into the corresp onding fused [1,2-a]pyrroles 8a-c, and 18a,b and fused [1,2-a]indoles 25, 27 by intramolecular cyclizations; the formations of 25 and 27 inv olve [3 + 2] and [3 + 3] annulations. The benzotriazoly-CH-ring moieti es of intermediates 8a,b, 18a,b, 25, and 27 were further elaborated: ( i) acylation of 8a and subsequent reduction and elimination promoted b y LiAlH4 to give product 6; (ii) nucleophilic displacements of the ben zotriazolyl moiety with NaCN, NaSPh, and Grignard reagents to afford c ompounds 9, 11, 12, 20, 29, and 32, respectively; (iii) base-assisted eliminations of benzotriazole from 8b and 18a to form the unsaturated fused [1,2-a]pyrroles 10 and 17; (iv) reactions of 18b and 25 with alp ha,beta-unsaturated ketone and aldehyde followed by acid-assisted elim ination of the benzotriazolyl group to yield tricyclic compound 21 and product 31; and (v) Lewis acid promoted dimerization of 27 to form th e fused indolo[3,2-b]carbazole 33.