Homogeneous pressure hydrogenation of quinolines effected by a bench-stable tungsten-based pre-catalyst

We report on an operationally simple catalytic method for the tungsten-catalyzed hydrogenation of quinolines through the use of the easily handled and self-contained precursor [WCl(eta(15)-Cp)(CO)(3)]. This half sandwich complex is indefinitely storable on the bench in simple screw-capped bottles or stoppered flasks and can, if required, be prepared on a multi-gram scale while the actual catalytic transformations were performed in the presence of a Lewis acid in order to achieve both decent substrate conversions and product yields. The described method represents a facile and atom-efficient access to a variety of 1,2,3,4-tetrahydroquinolines that circumvents the use of cost-intensive and oxygen-sensitive phosphine ligands as well as auxiliary hydride reagents. (C) 2021 The Author(s). Published by Elsevier Inc.

Automated summary

This study reports a simple catalytic method for the hydrogenation of quinolines using a tungsten precursor. The method is operationally simple and avoids the use of expensive and oxygen-sensitive phosphine ligands and auxiliary hydride reagents.