Palladium-catalyzed highly efficient synthesis of functionalized indolizines via cross-coupling/cycloisomerization cascade.

An efficient Pd-catalyzed cross-coupling/cycloisomerization of 3-(2-pyridyl) propargyl carbonates with organoboronic acids has been developed, which provides a straightforward route for the synthesis of 1,3-disubstituted indolizines with a wide variety of substituents. The mechanistic study indicates that the reaction proceeds via formation of an allenyl pyridine intermediate through palladium-catalyzed coupling reaction followed by cyclization.