Palladium-Catalyzed Direct C-3 Alkynylation of Indolizines with (2,2-Dibromovinyl)arenes

Abstract

The direct C-3 alkynylation of indolizines with (2,2-dibromovinyl)arenes in the presence of palladium catalyst has been developed. This novel protocol showed wide substrate scope with respect to both indolizines and dibromoalkenes. Also this method was characterized with high efficiency and good functional group tolerance.

GRAPHICAL ABSTRACT

Keywords:

• Alkynylation
• C-H activation
• (2,2-dibromovinyl)arenes
• indolizines

Notes

^a All reactions were run with indolizine-1-carbonitrile (0.3 mmol), (2,2-dibromovinyl) benzene (0.9 mmol), catalyst (0.03 mmol), ligand (0.06 mmol), base (0.9 mmol), and solvent (2 mL), at 100 °C for 24 h under N₂.

^b DPEPhos = oxybis(2,1-phenylene)bis(diphenylphosphine).

^c Isolated yields of alkynylation.

^d When AgOAc (2 equiv) was added.

^a Reaction conditions: Indolizines (0.3 mmol), (2,2-dibromovinyl)benzene (0.9 mmol), Pd(OAc)₂ (0.03 mmol), DPEPhos (0.06 mmol), AgOAc (0.6 mmol), and CsOAc (0.9 mmol), DMF (2 mL), 100 °C, 24 h, N₂.

^b Isolated yields.

^a Reaction conditions: indolizine-1-carbonitrile (0.3 mmol), (2,2-dibromovinyl)arenes (0.9 mmol), Pd(OAc)₂ (0.03 mmol), DPEPhos (0.06 mmol), AgOAc (0.6 mmol), and CsOAc (0.9 mmol), DMF (2 mL), 100 °C, 24 h, N₂.

^b Isolated yields.