One-Pot Synthesis of Indolizines from Pyridines, Benzyl Halides, and Alkenes

Significance

Reported is the synthesis of 3-arylindolizines 5 from pyridines 1, benzyl halides 2 and electron-deficient dihaloalkenes 4 via a one-pot alkylation-1,3-dipolar cycloaddition strategy. Both EDGs and EWGs are tolerated on the benzyl halide fragment. However, substrates bearing substituents ortho to the pyridine nitrogen (2-methylpyridine, 2-bromopyridine, quinoline) failed to give any of the desired indolizines. The reaction is tolerant of a wide range of dihaloalkenes, giving rise to indolizines 6-9 in moderate yields.