Palladium-catalyzed asymmetric allenylic alkylation: construction of multiple chiral thiochromanone derivatives

The development of a new strategy for the construction of chiral cyclic sulfide-containing multiple stereogenic centers is highly desirable. Herein, by the combination of base-promoted retro-sulfa-Michael addition and palladium-catalyzed asymmetric allenylic alkylation, the streamlined synthesis of chiral thiochromanones containing two central chiralities (including a quaternary stereogenic center) and an axial chirality (allene unit) was successfully realized with up to 98% yield, 49.0 : 1 dr and >99% ee.

One-pot asymmetric synthesis of a hexahydrophenanthridine scaffold containing five stereocenters via an organocatalytic quadruple-cascade reaction

An organocatalytic enantioselective aza-Michael-Michael-Michael/aldol cyclization quadruple-cascade reaction of 2-amino-β-nitrostyrenes and α,β-unsaturated aldehydes has been developed for the construction of fully substituted hexahydrophenanthridine.

3-Homoacyl coumarin: an all carbon 1,3-dipole for enantioselective concerted (3+2) cycloaddition

A new type of all-carbon 1,3-dipole precursor, 3-homoacylcoumarin, was employed for the stereoselective (3+2) cycloaddition with indandione alkylidenes to generate a series of coumarin/indandione-fused spirocyclopentanes bearing four contiguous stereogenic centers. While two reaction pathways progressed simultaneously, detailed mechanistic investigation revealed that the highly efficient stereoselective concerted route dominated the extremely slow stepwise pathway.

A dynamic kinetic asymmetric transfer hydrogenation–cyclization tandem reaction: an easy access to chiral 3,4-dihydro-2H-pyran-carbonitriles

A catalytic enantioselective dynamic kinetic asymmetric transfer hydrogenation–cyclization tandem reaction is developed for 1,3-difunctionalized racemic ketones.

Asymmetric synthesis of CF3-containing tetrahydroquinoline via a thiourea-catalyzed cascade reaction

The first example of the asymmetric introduction of CF₃ into the 2-position of tetrahydroquinolines was described by using β-CF₃-nitroalkene as the building block.

Synthesis and antiproliferative activity of sulfa-Michael adducts and thiochromenes derived from carbohydrates

The synthesis of new carbohydrate-derived 3-nitro-2H-thiochromenes with potential antiproliferative activity is described.

Recent Advances in Dynamic Kinetic Resolution by Chiral Bifunctional (Thio)urea- and Squaramide-Based Organocatalysts

The organocatalysis-based dynamic kinetic resolution (DKR) process has proved to be a powerful strategy for the construction of chiral compounds. In this feature review, we summarized recent progress on the DKR process, which was promoted by chiral bifunctional (thio)urea and squaramide catalysis via hydrogen-bonding interactions between substrates and catalysts. A wide range of asymmetric reactions involving DKR, such as asymmetric alcoholysis of azlactones, asymmetric Michael–Michael cascade reaction, and enantioselective selenocyclization, are reviewed and demonstrate the efficiency of this strategy. The (thio)urea and squaramide catalysts with dual activation would be efficient for more unmet challenges in dynamic kinetic resolution.

(Thio)urea-mediated synthesis of functionalized six-membered rings with multiple chiral centers

Organocatalysis, now running its second decade of life, is being considered one of the main tools a synthetic chemist has to perform asymmetric catalysis. In this review the synthesis of six-membered rings, that contain multiple chiral centers, either by a ring closing process or by a functionalization reaction on an already existing six-membered ring, utilizing bifunctional (thio)ureas will be summarized. Initially, the use of primary amine-thioureas as organocatalysts for the above transformation is being discussed, followed by the examples employing secondary amine-thioureas. Finally, the use of tertiary amine-thioureas and miscellaneous examples are presented.

Current advances of organocatalytic Michael–Michael cascade reaction in the synthesis of highly functionalized cyclic molecules

Organocatalytic domino/cascade reactions provide a convenient method for the construction of highly functionalized cyclic molecular structures bearing multiple stereocenters in a highly stereoselective fashion.

Highly enantioselective sulfa-Michael addition reactions using N-heterocyclic carbene as a non-covalent organocatalyst

We report the first asymmetric sulfa-Michael addition (SMA) reactions using a chiral N-heterocyclic carbene (NHC) as a non-covalent organocatalyst. We demonstrate that a triazolium salt derived NHC functions as an excellent Brønsted base to promote enantioselective carbon-sulfur bond formation. The reaction is applicable to a wide range of thiols and electrophilic olefins. Notably, quaternary chiral centers bearing both an S atom and a CF3 group were synthesized with excellent asymmetric control. Mechanistic studies suggest that the facial discrimination is likely to be guided by non-covalent interactions: hydrogen bonding and π-π stacking.

Enantioselective cascade double Michael addition of 3-nitro-2H-chromenes and acyclic enones: efficient synthesis of functionalized tricyclic chroman derivatives

An efficient protocol for the construction of enantiomerically enriched tetrahydro-6H-benzo[c]chromenes by the cascade double Michael addition of 3-nitro-2H-chromenes and α,β-unsaturated ketones catalyzed by a quinine-derived primary amine has been developed.

Peptide-catalyzed consecutive 1,6- and 1,4-additions of thiols to α,β,γ,δ-unsaturated aldehydes

Regio- and enantioselective addition of thiols to α,β,γ,δ-unsaturated aldehydes was performed with a resin-supported peptide catalyst. It was shown that a 1,4-adduct was generated mainly at the initial stage of the reaction, and this was eventually converted to a thermodynamically stable 1,6- and 1,4-diadduct through retro-addition/addition reactions.