Title:Application of Nitrogen Heterocyclic Carbenes in Organocatalysis
Volume: 10
Issue: 1
Author(s): Minita Ojha and R. K. Bansal*
Affiliation:
- Department of Chemistry, The IIS (deemed to be) University, Jaipur 302020,India
Keywords:
Nitrogen Heterocyclic carbenes, organocatalysts, benzoin condensation, cycloadditions, isomerization, esterification.
Abstract:
Background: During the last two decades, horizon of research in the field of Nitrogen
Heterocyclic Carbenes (NHC) has widened remarkably. NHCs have emerged as ubiquitous species
having applications in a broad range of fields, including organocatalysis and organometallic chemistry.
The NHC-induced non-asymmetric catalysis has turned out to be a fruitful area of research in
recent years.
Methods: By manipulating structural features and selecting appropriate substituent groups, it has
been possible to control the kinetic and thermodynamic stability of a wide range of NHCs, which
can be tolerant to a variety of functional groups and can be used under mild conditions. NHCs are
produced by different methods, such as deprotonation of N-alkylhetrocyclic salt, transmetallation,
decarboxylation and electrochemical reduction.
Results: The NHCs have been used successfully as catalysts for a wide range of reactions making
a large number of building blocks and other useful compounds accessible. Some of these reactions
are: benzoin condensation, Stetter reaction, Michael reaction, esterification, activation of esters,
activation of isocyanides, polymerization, different cycloaddition reactions, isomerization, etc. The
present review includes all these examples published during the last 10 years, i.e., from 2010 till
date.
Conclusion: The NHCs have emerged as versatile and powerful organocatalysts in synthetic organic
chemistry. They provide the synthetic strategy which does not burden the environment with
metal pollutants and thus fits in the Green Chemistry.
