A unique annulation of 7-azaindoles with alkenyl esters to produce π-conjugated 7-azaindole derivatives

Abstract

Rhodium(iii)-catalyzed N-directed ortho C-H activation and subsequent roll-over C-H activation represents an important strategy to synthesize fused polycyclic compounds. Herein, the novel methodology broadens the scope of the coupling partner to alkenes, which working smoothly with 7-azaindoles has been proven to be an efficient and atom-economical strategy to access complex π-conjugated 7-azaindole derivatives.

A comprehensive overview of directing groups applied in metal-catalysed C–H functionalisation chemistry

“…The group-directed ortho -alkylation with diazocompounds or via addition to alkenyl esters, followed by intramolecular activation of the azaindole C2, and finally by dehydration or β-H elimination, results in the products in Scheme 157H and I . 972 , 973 The reaction with alkynes, occurring as previously reported for other DGs, was also investigated ( Scheme 157J and K ). 974 , 975 Interesting in this respect is the reaction with 3 equiv.…”

Oxidative Alkenylation of Fused Bicyclic Heterocycles

“…Very recently, Dong and co-workers [76] reported an interesting annulation of 7-azaindoles with alkenyl esters leading to πconjugated 7-azaindole derivatives. The reactions were conducted on azaindole 67 using 2 equiv.…”

Regioselective Direct C‐Alkenylation of Indoles

“…Recently, various 1‐aryl‐7‐azaindoles have been used as common substrates in different reactions with alkenes catalyzed by Rh III complexes aimed at the preparation of tetraheterocyclic derivatives. Reaction of enol acetates 12 with these substrates affords pyridopyrroloquinolines in moderate to satisfactory yields depending on the nature of the enol moiety (Scheme ) . The 7‐azaindole system is instrumental for the success of the reaction since a plausible mechanism implies the formation of a first intermediate 13 in which the C−C bond formation occurs with the benzene ring.…”

“…Reaction of enol acetates 12 with these substrates affords pyridopyrroloquinolines in moderate to satisfactoryy ields depending on the nature of the enol moiety (Scheme 23). [63] The 7-azaindole system is instrumental for the successo ft he reactions ince ap lausible mechanism implies the formation of af irst intermediate 13 in which the CÀC bond formation occurs with the benzene ring. The metal is stabilized by ad ouble coordination with the carbonyl oxygen and the nitrogen atom.…”