Ir-Catalyzed Asymmetric Hydrogenation of N -Fused Heteroarenes with High Nitrogen Density: An Access to Chiral 2,5-Disubstituted 5,6-Dihydropyrrolo[1,2- a ][1,2,4]triazolo[5,1- c ]pyrazines.

A highly enantioselective Ir-catalyzed asymmetric hydrogenation of 2,5-disubstituted pyrrolo[1,2- a ][1,2,4]triazolo[5,1- c ]pyrazines containing four nitrogen atoms has been first realized. Under additive-free conditions, a variety of chiral 2,5-disubstituted 5,6-dihydropyrrolo[1,2- a ][1,2,4]triazolo[5,1- c ]pyrazines can be afforded in high yields (86-98%) with excellent enantioselectivities of up to 99% ee. This method provides a straightforward strategy for the efficient synthesis of chiral multinitrogen polyheterocyclic compounds.