Enantioselective synthesis of trans-dihydrobenzofurans via primary amine-thiourea organocatalyzed intramolecular Michael addition.

A primary amine-thiourea organocatalyzed intramolecular Michael addition access was developed for the synthesis of trans-dihydrobenzofurans. Under the catalysis of an (R,R)-1,2-diphenylethylamine derived primary amine-thiourea bearing a glucosyl scaffold, the corresponding trans-dihydrobenzofurans were obtained in high yields with excellent level of enantioselectivities (94 to >99% ee). Moreover, an in situ isomerization occurring at high temperature gave good to excellent trans/cis ratios as well (trans/cis: 84/16-96/4).

Organocatalyzed enantioselective michael addition of 2-hydroxy-1,4-naphthoquinone to ß,γ-unsaturated α-ketophosphonatesθ.

By employing a cinchonine-based thiourea as catalyst, highly enantioselective Michael addition reactions of 2-hydroxy-1,4-naphthoquinone to ß,γ-unsaturated α-ketophosphonates were realized. The reaction afforded the corresponding ß-substituted carboxylates in excellent yields with high levels of enantioselectivities (94->99% ee) upon quenching the generated parent structures with DBU and MeOH as a second nucleophile.

A recyclable organocatalyst for asymmetric Michael addition of acetone to nitroolefins.

Based on different chiral diamine skeletons, a series of bifunctional primary amine-thiophosphoramides were synthesized and screened as the catalysts for the asymmetric Michael addition of acetone to both aromatic and aliphatic nitroolefins. Under the catalysis of a thiophosphoramide derived from 1,2-diphenylethane-1,2-diamine, the corresponding adducts were obtained in high yields (up to >99%) with excellent enantioselectivities (97-99% ee) under mild reaction conditions. Moreover, the catalyst could be recovered via simple phase separation and reused at least five times without any loss of both catalytic activity and stereocontrol.

Novel bifunctional chiral thiourea catalyzed highly enantioselective aza-Henry reaction.

A novel bifunctional chiral thiourea organocatalyst bearing a glycosyl scaffold and a tertiary amino group was synthesized starting from readily available alpha-D-glucose. This thiourea was proven to be an effective organocatalyst for the asymmetric aza-Henry reaction between N-Boc imines and nitromethane. The corresponding adducts were obtained in good to excellent yields with excellent enantioselectivities (up to 99.8% ee). In addition, the reaction of nitroethane also proceeded smoothly with excellent enantioselectivity, albeit with low to good diastereoselectivities.

Dramatic rate acceleration of the Baylis-Hillman reaction in homogeneous medium in the presence of water.

[reaction: see text] In homogeneous H(2)O/solvent medium, the reaction rate of aromatic aldehydes and acrylonitrile or acrylate was greatly accelerated, which led to shorter reaction time, lower reaction temperature, and higher yield. In this reaction, Me(3)N, DMAP, DABCO, and urotropine were good catalysts. Except for low-carbon alcohols, tetrahydrofuran, 1,4-dioxane, and acetonitrile could be chosen as the solvent. Under this condition, the diastereoselective reaction of nitrobenzaldehyde and L-menthyl acrylate was realized with 88-99% de.

Enantioselective organocatalytic domino Michael/aldol reactions: an efficient procedure for the stereocontrolled construction of 2H-thiopyrano[2,3-b]quinoline scaffolds.

An efficient procedure for the stereocontrolled construction of 2H-thiopyrano[2,3-b]quinoline scaffolds has been developed, starting from simple compounds. The domino Michael/aldol reactions between 2-mercaptobenzaldehydes and enals, promoted by chiral diphenylprolinol TMS ether, proceed with excellent chemo- and enantioselectivity to give the corresponding synthetically useful and pharmaceutically valuable 2H-thiopyrano[2,3-b]quinolines in high yields with 90-99 % ee.

Stereoselective synthesis of highly functionalized nitrocyclopropanes through the organocatalyic Michael-addition-initiated cyclization of bromonitromethane and ß,γ-unsaturated α-ketoesters.

A highly diastereo- and enantioselective cyclopropanation of ß,γ-unsaturated α-ketoesters with bromonitromethane has been successfully developed through a domino Michael-addition/intramolecular-alkylation strategy. Acceptable yields (up to 89%) and enantioselectivities (up to 96% ee) have been obtained.

Chiral (thio)phosphorodiamides as excellent hydrogen bond donor catalysts in the asymmetric Michael addition of 2-hydroxy-1,4-naphthoquione to nitroolefins.

A novel type of bidentate hydrogen bond donor catalysts based on (thio)phosphorodiamides catalophore has been developed for the asymmetric Michael addition of 2-hydroxy-1,4-naphthoquione to nitroolefins, affording the corresponding adducts in high yields with excellent level of enantioselectivities (97- >99% ee).