Selective Cu-Catalyzed Intramolecular Annulation of 3-Aryl/Heteryl-2-(diazoacetyl)-1 H -pyrroles: Synthesis of Benzo/Furo/Thieno[ e ]-Fused 1 H -Indol-7-oles and Their Transformations

The Co(III)-catalyzed reaction of 1,3-dicarbonyl compounds with 2-(diazoacetyl)-2 -azirines, prepared by a simplified procedure from 2 -azirin-2-carbonyl chlorides, led in high yields to the formation of 2-(diazoacetyl)pyrroles, while leaving the diazoacetyl function intact. The intramolecular aromatic substitution reaction of 2-(diazoacetyl)pyrroles, catalyzed by Cu(OTf) , provided selectively previously unknown benzo[ ]- and hetero[ ]-fused indol-7-oles in good yields. Formylation of benzo[ ]indol-4-ol led selectively to the 5-formyl derivative, which is a good precursor for an unusual salen ligand and its Ni-complex. Triflates prepared from benzo[ ]indol-4-oles gave various 4-substituted benzo[ ]indoles carrying aryl, 2-thienyl, 2-pyridyl, and alkynyl groups, in excellent yields using cross-coupling reactions. 4-(2-Pyridyl)benzo[ ]indoles, upon treatment with BF ·Et O/Et N, afforded a new type of fluorescent boron complexes with large Stokes shifts.