Glucose‐based Ionic Liquid Organocatalysts for Asymmetric aza‐Diels‐Alder Reactions

Abstract

Carbohydrate‐based ionic liquids and salts (CHILS) have recently emerged as an uprising sub‐class of ionic liquids. Their starting materials are available in abundant natural resources from plants and fauna. Carbohydrates are not only sustainable; they also exhibit natural chirality. To use this, novel glucosyl imidazolium NTf2 ionic liquids were synthesized and applied as organocatalysts in aza‐Diels‐Alder reactions in this work, where we used aldimines and Danishefsky's diene as substrates. We investigated the structure‐activity relationships of these glucosyl imidazolium NTf2 organocatalysts through several functionalizations on the carbohydrate and the imidazole and compared them with common metal catalysts and ionic liquids. Our organocatalysts improved the yield of the model aza‐Diels‐Alder reaction highly and also had a positive effect on the overall diastereomeric excess.