Iridium-catalyzed asymmetric hydrogenation of 5-hydroxypicolinate pyridinium salts under batch and flow: stereodefined access to cis-configurated hydroxypiperidine esters

An iridium-catalyzed asymmetric hydrogenation of 2-esteryl-5-hydroxypyridinium salts is reported, providing chiral cis -5-hydroxypiperidine-2-carboxylates in excellent yields with high levels of enantioselectivities and diastereoselectivities.