Catalysis with Supported Organocatalysts
Asymmetric organocatalysis is a rapidly growing area of modern organic chemistry. Organocatalysts can be used for electrophilic substitutions in α-position of saturated aldehydes and ketones as well as for nucleophilic additions to nitroethenes and α,β-unsaturated aldehydes and ketones. Organocatalysed cycloadditions are also described. In recent years many papers have been published describing applications of organocatalysts in domino reactions leading to natural products or potential medicaments. Drawbacks of organocatalytic reactions are that higher catalyst loadings must often be used, reactions are rather slow, and must be carried out in organic solvents. The main purpose of this review is to point out that application of unusual solvents, such as water or ionic liquids, as well as unusual conditions, such as microwave irradiation, ultrasonication or ball milling, can have some advantages with organocatalytic reactions.