NEW SUBSTITUTION REACTIONS ON INDOLE PROMOTED BY THE Cr(CO)3 UNIT

Article abstract of DOI:10.1016/S0022-328X(00)93987-1

Indole derivatives form complexes with the Cr(CO)3 unit at the 6-membered ring.Addition of reactive carbon nucleophiles occurs at the coordinated ring with strong preference for C-4 and, in a few cases, for C-7.Oxidation of the intermediate cyclohexadienyl anionic complexes produces substituted indoles in good yield.Complexes of N-methylindoline and benzofuran also undergo the addition/oxidation sequence preferentially at C-4.Changes in the substituents at C-3 and the nitrogen atom in the indole complexes influences the regioselectivity so that either C-4 or C-7 substitution can be observed.The selectivity is correlated with EHT calcualtions on free indole and complexes indole.