Multicomponent reactions in ionic liquids: convenient and ecocompatible access to the 2,6-DABCO core

Abstract

Herein we describe the use of ionic liquids as complementary new media for multicomponent reactions leading to the 2,6-diazabicyclo[2.2.2]octane core. The reaction took place efficiently in ionic liquid solvents instead of toluene, giving overall better results (faster rate, higher concentration) and allowing generalization to hitherto unreactive substituted Michael acceptors. In these cases, the use of molecular sieves, acting as a heterogeneous catalyst in the preliminary study in molecular solvents, could be totally excluded thanks to the promoting properties of the ionic liquid solvent, which could be recycled and reused up to five times. Complete diastereoselectivity was observed at one of the bridge positions, as assigned by X-ray analysis.