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Chang Guo¹, Mirco Fleige¹, Daniel Janssen-Müller¹

¹Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstrasse 40, Münster 48149, Germany.

Nature Chemistry

|September 23, 2015

Summary

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Area of Science:

Organic Synthesis
Catalysis
Stereoselective Synthesis

Background:

Developing general catalytic methods for chiral N-heterocycles is challenging.
N-heterocyclic carbene (NHC) catalysis offers diverse outcomes but lacks reactivity control.

Purpose of the Study:

To develop a switchable catalytic activation of enals with aromatic azomethine imines.
To achieve high regio- and stereoselectivity in chiral N-heterocycle synthesis using NHC organocatalysts.

Main Methods:

Utilized N-heterocyclic carbene (NHC) organocatalysts for enal activation.
Employed aromatic azomethine imines and various electrophiles (N-iminoquinolinium, N-iminoisoquinolinium, β-N-iminocarboline ylides).
Controlled selectivity via base acidity and reaction conditions.

Main Results:

Achieved switchable catalytic activation of enals with high selectivity.
Generated chiral homoenolate or enol intermediates for enantioselective annulation.
Observed good-to-high yields, high regioselectivities, and excellent enantioselectivities.

Conclusions:

Demonstrated a novel NHC-catalyzed method for selective chiral N-heterocycle synthesis.
Highlighted the ability to control reactivity and selectivity through catalyst and reaction conditions.
Provided a versatile approach for diversity-oriented synthesis of complex N-heterocycles.