Tatsuya Urushima

Enantio- and diastereoselective synthesis of piperidines by coupling of four components in a "one-pot" sequence involving diphenylprolinol silyl ether mediated Michael reaction.

An efficient, asymmetric, four-component, one-pot synthesis of highly substituted piperidines with excellent diastereo- and enantioselectivity was established through the diphenylprolinol silyl ether mediated Michael reaction of aldehyde and nitroalkene, followed by the domino aza-Henry reaction/hemiaminalization reaction and a Lewis acid mediated allylation or cyanation reaction. All carbons of the piperidine ring are substituted with different groups, and its five contiguous stereocenters are completely controlled in both relative and absolute senses.

Polymeric Ethyl Glyoxylate in an Asymmetric Aldol Reaction Catalyzed by Diarylprolinol

Diarylprolinol was found to be an effective organocatalyst of the direct, enantioselective aldol reaction of commercially available polymeric ethyl glyoxylate, affording gamma-ethoxycarbonyl-beta-hydroxy aldehydes, versatile synthetic intermediates, in good yield with excellent enantioselectivity.

Asymmetric epoxidation of α-substituted acroleins catalyzed by diphenylprolinol silyl ether.

Asymmetric epoxidation of α-substituted acroleins with hydrogen peroxide has been catalyzed by diphenylprolinol diphenylmethylsilyl ether to afford α-substituted-β,β-unsubstituted-α,β-epoxy aldehyde with excellent enantioselectivity and the generation of a chiral quaternary carbon center. The method was applied to a short synthesis of (R)-methyl palmoxirate.

L-proline-catalyzed enantioselective one-pot cross-Mannich reaction of aldehydes.

This protocol describes a procedure for the synthesis of syn-β-amino α-substituted aldehydes, versatile intermediates in synthetic organic chemistry, via asymmetric, direct, one-pot, three-component, cross-Mannich reaction of two different aldehydes. The reaction consists of two steps; one is the formation of imine by the reaction of aldehyde and p-anisidine in the presence of Pro, and the second step is the enantioselective addition reaction of enamine generated from the other aldehyde and Pro with the imine generated in the first step. As the aldehyde easily racemizes, γ-amino alcohol was isolated and characterized after reduction. The yield and diastereo- and enantioselectivities are generally excellent. It will take approximately 26 h to complete the protocol: 0.5 h to set up the reaction, 20.5 h for the reaction and 5 h for the isolation and purification.