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Dienamine catalysis: organocatalytic asymmetric gamma-amination of alpha,beta-unsaturated aldehydes.

Journal of the American Chemical Society (2006-09-28)
Søren Bertelsen, Mauro Marigo, Sebastian Brandes, Peter Dinér, Karl Anker Jørgensen
ABSTRACT

A new concept in organocatalysis is presented, the direct asymmetric gamma-functionalization of alpha,beta-unsaturated aldehydes. We disclose that secondary amines can invert the usual reactivity of alpha,beta-unsaturated aldehydes, enabling a direct gamma-amination of the carbonyl compound using azodicarboxylates as the electrophilic nitrogen-source. The scope of the reaction is demonstrated for the enantioselective gamma-amination of different alpha,beta-unsaturated aldehydes, giving the products in moderate to good yields and with high enantioselectivities up to 93% ee. Experimental investigations and DFT calculations indicate that the reaction might proceed as a hetero-Diels-Alder cycloaddition reaction. Such a mechanism can explain the "unexpected" stereochemical outcome of the reaction.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
N-Methylmaleimide, 97%
Sigma-Aldrich
(S)-α,α-Bis(3,5-dimethylphenyl)-2-pyrrolidinemethanol trimethylsilyl ether hydrochloride, 97%