Ernst Schering Foundation Symposium Proceedings, Vol. 2, pp. 183–206
DOI 10.1007/2789_2008_079
© Springer-Verlag Berlin Heidelberg
Published Online: 30 April 2008
N-Heterocyclic Carbenes: Organocatalysts
Displaying Diverse Modes of Action
K. Zeitler
(u)
Institut für Organische Chemie, Universität Regensburg, Universitätsstr. 31,
93053 Regensburg, Germany
email: kirsten.zeitler@chemie.uni-regensburg.de
1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
2
Catalyst Structures and Preparation . . . . . . . . . . . . . . . . . 185
3
Classification of NHC-Mediated Reactions . . . . . . . . . . . . . 190
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199
Abstract. Within the context of Lewis base catalysis N-heterocyclic carbenes
represent an extremely versatile class of organocatalyst that allows for a great
variety of different transformations. Starting from the early investigations on
benzoin, and later Stetter reactions, the mechanistic diversity of N-heterocyclic
carbenes, depending on their properties, has led to the development of several
unprecedented catalytic reactions. This article will provide an overview of the
versatile reactivity of N-heterocyclic carbenes.
1
Introduction
Chemists have been inspired by Nature for hundreds of years, not only
trying to understand the chemistry that occurs in living systems, but also
trying to extend Nature based on the learned facts. Although already
pointed out by Langenbeck in the late 1920s (Langenbeck 1928) that,
unlike frequent remarks regarding analogies of enzymes to inorganic
DOI 10.1007/2789_2008_079
© Springer-Verlag Berlin Heidelberg
Published Online: 30 April 2008
N-Heterocyclic Carbenes: Organocatalysts
Displaying Diverse Modes of Action
K. Zeitler
(u)
Institut für Organische Chemie, Universität Regensburg, Universitätsstr. 31,
93053 Regensburg, Germany
email: kirsten.zeitler@chemie.uni-regensburg.de
1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
2
Catalyst Structures and Preparation . . . . . . . . . . . . . . . . . 185
3
Classification of NHC-Mediated Reactions . . . . . . . . . . . . . 190
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199
Abstract. Within the context of Lewis base catalysis N-heterocyclic carbenes
represent an extremely versatile class of organocatalyst that allows for a great
variety of different transformations. Starting from the early investigations on
benzoin, and later Stetter reactions, the mechanistic diversity of N-heterocyclic
carbenes, depending on their properties, has led to the development of several
unprecedented catalytic reactions. This article will provide an overview of the
versatile reactivity of N-heterocyclic carbenes.
1
Introduction
Chemists have been inspired by Nature for hundreds of years, not only
trying to understand the chemistry that occurs in living systems, but also
trying to extend Nature based on the learned facts. Although already
pointed out by Langenbeck in the late 1920s (Langenbeck 1928) that,
unlike frequent remarks regarding analogies of enzymes to inorganic