New N-alkyl-3,3'-bimorpholine derivatives (iPBM) were revealed to be efficient organocatalysts for the asymmetric direct Michael addition of aldehydes to nitroolefins and a vinyl sulfone. In these transformations using iPBM, 1,4-adducts were afforded in high yields, with good to high levels of diastereo- and enantioselectivity. The stereochemical outcome of the reaction could be explained by an acyclic synclinal model. [reaction: see text]

[reaction: see text] The first asymmetric direct Michael addition of aldehydes to vinyl sulfones catalyzed by N-iPr-2,2'-bipyrrolidine is described. 1,4-Adducts are obtained in good yields and enantioselectivities. The determination of absolute configuration allowed us to postulate a Si,Si transition state model, as shown previously for nitroolefins.

[reaction: see text] Organocatalyzed asymmetric microwave-assisted reactions are described. Significant rate enhancements and a decrease of catalyst loading via microwave activation have been observed, while maintaining good to high yields and selectivities compared to literature results.

The recent rapid growth of organocatalysis has shown a new approach in organic chemistry and presents the obvious advantage in the avoidance of expensive and often toxic metals. Moreover, the organocatalysts are generally easier to make than standard catalytic reagents. Therefore, our laboratory has synthesized N-alkyl-2,2'bipyrrolidine derivatives as a new class of organocatalysts and applied them to the asymmetric Michael addition of ketones and aldehydes to nitroolefins via an enamine intermediate. We have furthermore developed the first asymmetric Michael addition of aldehydes to vinyl sulfones catalyzed with our diamines. The 1,4 adducts are obtained in good yields with enantioselectivities up to 80% ee. The determination of absolute configuration allowed us to postulate a Si,Si transition state model, as described previously for nitroolefins.