Radical-carbene coupling reaction: Mn-catalyzed synthesis of indoles from aromatic amines and diazo compounds

Abstract

An unprecedented coupling reaction between aromatic amines and diazo compounds was well developed, which afforded a bridge connecting between radical chemistry and metal carbene chemistry. This Mn-catalyzed tandem reaction also provided a fundamentally different and practical approach to the indole skeleton under mild conditions.

Rapid Interception of CnF2n+1(O)SO. Radical with Copper‐Based Carbene: A Novel Access to Perfluoroalkanesulfinate Ester

“…Radical–carbene coupling (RCC) is considered a promising and mechanistically interesting strategy for the synthesis of polyfunctionalized molecules considering that both of them have low concentrations in the reaction system. Recently, we reported the direct coupling of α‐aminoalkyl radicals and metal carbenes to generate β‐ester‐γ‐amino ketones, and indoles . We also developed a RCC method that allowed the efficient preparation of isoxazolines from Cu‐based carbenes and nitroso radicals under mild conditions .…”

Recent Progress in the Transition Metal Catalyzed Synthesis of Indoles

“…About the mechanism, some kinetic experiments allowed envisaging a mechanism that parallels the rhodium-catalyzed variant [142]. A quite different approach to indole synthesis has been proposed by Wan and co-workers [143], who set up a radical-carbene coupling reaction (Scheme 74). The reaction of meta-toluidine yielded a 2:1 mixture of 4-and 6-isomers.…”

Construction of N‐Heterocycles through Cyclization of Tertiary Amines

“…Wan et al. established a new approach to the cyclization of simple tertiary amines 98 with diazo compound 99 (Scheme ) . In this transformation, the merging of radical species with metal carbene was proven feasible to promote the radical addition/cyclization process.…”

“…established an ew approacht ot he cyclization of simple tertiarya mines 98 with diazo compound 99 (Scheme 41). [90] In this transformation,t he merging of radical speciesw ith metal carbene was proven feasible to promote the radical addition/cyclization process. Mn(OAc) 2 ·4H 2 Ow as found to be an appropriate catalystt og enerate metal carbene species M42 whereas cis-4,4'-azobis(4-cyanovaleric acid) (ACVA) was selected as the optimal choice of radical initiator capable of abstracting ah ydrogen atom from the tertiary amine.…”