Search

The regioselective asymmetric Michael addition of azlactones to o-hydroxy chalcone derivatives proceeds with complete C-2 regioselectivity by using quinine derived bifunctional thiourea tertiary amine as a catalyst.

The tandem oxo-Michael-IED/HDA and oxo-Michael-IED/HDA-Michael-Aldol condensation transformations between (E)-2-hydroxyaryl-2-oxobut-3-enoate derivatives with enals have been developed in the presence of (S)-diphenylprolinol trimethylsilyl ether as an organocatalyst. Two types of tricyclic chroman derivatives were, respectively, obtained, by adjusting the reactant ratio and reaction temperature, in good yields (up to 96%) with excellent enantioselectivities (up to >99%) and good diastereoselectivities (up to >30/1). It should be noted that the divergent chiral chroman derivatives were obtained by successive reaction of (E)-2-hydroxyaryl-2-oxobut-3-enoate derivatives with two different enal substrates in highly catalytic results.

A diastereo- and enantioselective domino Michael-cyclization-tautomerization reaction of isatylidene malononitriles (I) and (IV) with α,α-dicyanoalkenes catalyzed by a chinchona alkaloid-derived bifunctional catalyst is reported.

The synthesis of organophosphorus compounds is of great importance to industrial, agricultural, and pharmaceutical chemistry. In this paper, we have reported the synthesis of highly substituted pyrazole derivatives through P–C bond formation under catalyst-free conditions. On the other hand, the first catalytic asymmetric version of this reaction has also been developed under catalysis by an isosteviol derived thiourea organocatalyst. The optically active phosphorus-containing compounds have been obtained in good chemical yields with moderate enantioselectivities.

The highly efficient asymmetric reduction of title compounds (I), (III), and (V) using a phosphine-free chiral Ru-complex furnishing corresponding β-hydroxy sulfonamides and -sulfones (II), (IV), and (VI), resp., is described.

Pyrazoles are an important class of molecular structures with significant biological and pharmaceutical activities. Herein, heterocyclic compounds containing both a pyrazole motif and a masked amino acid structure are synthesized through the asymmetric Michael/aromatization of azlactones to α,β-unsaturated pyrazolones by using isosteviol-derived amine thiourea as the organocatalyst. The products are obtained in good yields (up to 93 %) with good diastereoselectivities and good enantioselectivities (up to >10:1 dr, 97 % ee).

Because of the importance of the indole framework and the versatile transformation of nitro and formyl groups, the efficient synthesis of optically pure 2-alkyl-3-(1H-indol-3-yl)-4-nitrobutanals, one type of tryptamine precursors are of great interest for pharmaceutical and biological research. Herein, the Michael addition of aliphatic aldehydes to indolylnitroalkenes has been developed using (S)-diphenylprolinol trimethylsilyl ether as an organocatalyst, which provides the desired optically pure syn 2-alkyl-3-(1H-indol-3-yl)-4-nitrobutanal derivatives in up to 98% yield with up to >99:1 dr and >99% ee. To show the synthetic usefulness of this methodology, optically active 2-alkyl-4-nitro-3-(1-tosyl-1H-indol-3-yl)butan-1-ol and tryptamine derivatives are readily obtained by stepwise systematic transformations.

An asymmetric methodology for the construction of formyl, hydroxyl, and ester functionalized spirocyclohexaneoxindoles in good yields with moderate diastereoselectivity and excellent enantioselectivity is reported.

Non-naturally enantioenriched cis-β-thio-α-amino acid derivatives were synthesized through one pot, cascade thio-Michael/ring opening reaction of aromatic thiols with (Z)-olefinic azlactones in good yields with high levels of diastereoselectivities and enantioselectivities, which was catalyzed by a chiral bifunctional thiourea–tertiary amine catalyst.

A series of optically active β-hydroxy sulfonamides were synthesized for the first time by asymmetric transfer hydrogenation of the corresponding β-ketosulfonamides using the Ru–TsDPEN–HCOOH–Et 3 N catalytic system, in excellent yields (up to 95%) with excellent diastereo- (up to > 99:1 dr) and enantioselectivities (up to >99% ee).