Gold/silver-catalyzed synthesis of functionalized indoles from N-allyl-2-alkynylanilines and α-diazo compounds via 1,3-allyl migration†

Gold-catalyzed synthesis of decorated indoles has been developed through carbene insertion into N–H bonds of N-allyl-2-(aryl/alkyl ethynyl)anilines using α-diazo compounds followed by cyclization and concomitant 1,3 migration of allyl fragments. The developed protocol tackles the inherited challenge of direct C3 functionalization and eliminates the need for a tertiary aniline precursor for the 1,3-migration reaction. The applicability of this transformation is showcased through the practical synthesis of analogs of small drug-like and pharmaceutically relevant molecules such as ibuprofen, estradiol, menthol, and borneol, etc. The mechanism is well supported by control experiments and isolation of the reaction intermediate.