Abstract
A new concept for the catalysis of the inverse-electron-demand
Diels-Alder (IEDDA) reaction of 1,2-diazenes using bidentate
Lewis acid was recently reported by our group. The general catalytic
principle is based on the simultaneous coordination of the bidentate
Lewis acid to the 1,2-diazene moiety, lowering the LUMO to facilitate
the cycloaddition step. Extrusion of N2 regenerates the
catalyst and after elimination the aromatic product is obtained.
In this account the development of this new catalytic principle
is described and put into the general context of Lewis acid catalysis.
1 Introduction
2 Interaction of Bidentate Lewis Acids with 1,2-Diazenes
3 Catalytic IEDDA Reaction of 1,2-Diazenes with a Bidentate
Lewis Acid
3.1 The General Principle of Catalysis
3.2 Evaluation of the Concept by Calculations
3.3 Synthesis of the Bidentate Lewis Acid Catalyst
3.4 Characterization of the Bidentate Lewis Acid-1,2-Diazene Complex
3.5 Catalysis of the IEDDA Reaction of 1,2-Diazenes
3.6 General Trends
4 Conclusion
Key words
Lewis acids - catalysis - Diels-Alder
reaction - boron - arenes