Direct Carbon−Carbon Bond Formation via Soft Enolization: A Biomimetic Asymmetric Mannich Reaction of Phenylacetate Thioesters
2010-08-06T00:00:00Z (GMT) by
An asymmetric Mannich reaction of phenylacetate thioesters and sulfonylimines using cinchona alkaloid-based amino (thio)urea catalysts is reported that employs proximity-assisted soft enolization. This approach to enolization is based on the cooperative action of a carbonyl-activating hydrogen bonding (thio)urea moiety and an amine base contained within a single catalytic entity to facilitate intracomplex deprotonation. Significantly, this allows thioesters over a range of acidity to react efficiently, thereby opening the door to the development of a general mode of enolization-based organocatalysis of monocarboxylic acid derivatives.
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