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A new and efficient method for diazenylation reactions was developed with a Sc(OTf)3-catalyzed nitrogen-nitrogen bond cleavage process with triazenes. The transfer diazenylation reactions accommodate a diverse range of active methylene substrates including simple ketones to give aliphatic azo compounds that are of significant potential as azo prodrugs in high yields under mild conditions.

The first effective example of asymmetric conjugate addition-protonation reactions of thiols to α-substituted vinyl ketones by chiral primary amine catalysis is reported. A simple chiral primary-tertiary diamine catalyst derived from l-phenylalanine was found to promote the sulfa-Michael addition-protonation reactions with good to excellent enantioselectivity.

A highly enantioselective catalytic double-Michael addition reaction of substituted benzofuran-2-ones with divinyl ketones promoted by readily accessible tertiary amine-thiourea Cinchona alkaloids has been developed. A number of optically enriched spirocyclic benzofuran-2-ones were prepared in very good yields (up to 99 %), diastereoselectivities (up to 19:1 d.r.), and very good enantioselectivities (up to 92 % ee). Density functional theory (DFT) calculations were performed to investigate the origin of stereoselectivity., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A regioselective [3 + 2] cycloaddition of benzofuranone type active olefins with allenoates catalyzed by trivalent phosphines has been developed, which provided an easy access to enriched functionalized spirocyclic benzofuranones. The reactions accommodated a number of benzofuranone type electron-deficient olefins and allenoates to give the desired 3-spirocyclopentane benzofuran-2-ones or 2-spirocyclopentane benzofuran-3-ones with moderate to excellent yields (up to 99%) and moderate to good regioselectivities (up to 11:1).

We describe herein a viable binary acid strategy for the catalytic Nazarov reaction of aryl vinyl ketones. Simply combining a Lewis acid and a Brønsted acid led to a dramatic enhancement of the catalytic activity in the Nazarov reaction of aryl vinyl β-ketoesters. The obtained optimal binary acid catalyst In(OTf)(3)/diphenyl phosphoric acid (DPP) can be applied to a range of aryl vinyl ketones with good activity. A trend of reactivity has also been summarized on the basis of mapping of the substituents.

This paper describes a simple chiral primary amine-catalyzed highly efficient and practical protocol for the synthesis of both Wieland-Miescher ketone and Hajos-Parrish ketone as well as their analogues. The reaction can be conducted in gram scale with 1% mol catalyst loading producing high enantioselectivity (up to 96% ee) and excellent yields (up to 98%). This procedure represents one of the most efficient methods for the synthesis of these versatile chiral building blocks.

A series of primary-tertiary diamine catalysts were designed and synthesized from primary natural amino acids. Application of these new chiral catalysts in direct aldol reactions of alpha-hydroxyketones showed very good catalytic activity (up to 97% yield) and high syn selectivity (up to syn/ anti = 30:1, 99% ee).

Functionalized chiral ionic liquids were found to be highly effective and reusable organocatalysts for asymmetric Michael additions of 4-substituted cyclohexanones. The desymmetrization reaction afforded the desired Michael adducts bearing three carbon stereocenters with up to 99% ee.

The hydrogen transfer mechanism of cofactor reduction and recycling processes in the yeast reduction of alpha,beta-unsaturated ketone was studied by using quantitative isotope tracing close to natural abundance measured by (2)H NMR. In the reaction, the active cofactor is NADPH. The cofactor-transferred hydride attacks the beta sp(2) carbon of the enone carbonyl while water hydrogen is transferred to the alpha position. The reductant involved in the reaction depends on the quantity of yeast. When the amount of yeast is very large, the enzymes use preferentially certain unidentified substance stored in the yeast cells rather than the added glucose as electron donor. In this case, the hydrogen transferred by the cofactor is mainly of water origin. When the yeast amount is low, the added glucose is more efficiently used by the enzymes as electron donor and its hydrogen atoms bound to C-1 and C-3 are delivered to the substrate.

We report the first example of the enantioselective conjugate addition of alkenes (aromatic enamines) to enones catalyzed by chiral primary amines. The reactions encompass a plethora of α,β-enones including difficult α-substituted vinyl ketones to give vinylation adducts in high yields with good enantioselectivity. The methodology is of synthetic potential in accessing chiral functional materials. [ABSTRACT FROM AUTHOR]

Enantioselective protonation with a catalytic enamine intermediate represents a challenging, yet fundamentally important process for the synthesis of α-chiral carbonyls. We describe herein chiral primary-amine-catalyzed conjugate additions of indoles to both α-substituted acroleins and vinyl ketones. These reactions feature enamine protonation as the stereogenic step. A simple primary-tertiary vicinal diamine 1 with trifluoromethanesulfonic acid (TfOH) was found to enable both of the reactions of acroleins and vinyl ketones with good activity and high enantioselectivity. Detailed mechanistic studies reveal that these reactions are rate-limiting in iminium formation and they all involve a uniform H2O/acid-bridged proton transfer in the stereogenic steps but divergent stereocontrol modes for the protonation stereoselectivity. For the reactions of α-branched acroleins, facial selections on H2O-bridged protonation determine the enantioselectivity, which is enhanced by an OH⋅⋅⋅π interaction with indole as uncovered by DFT calculations. On the other hand, the stereoselectivity of the reactions with vinyl ketones is controlled according to the Curtin-Hammett principle in the CC bond-formation step, which precedes a highly stereospecific enamine protonation. [ABSTRACT FROM AUTHOR]

Abstract: Simple mixing of chiral amines and surfactant Brønsted acids such as p-dodecyl benzenesulfonic acid (DBSA) leads to highly effective and selective organocatalysts in water. The in situ generated catalysts catalyze highly stereoselective desymmetrization of prochiral ketones via direct aldol reactions (up to >16:1 dr, >99% ee) in water using micelle as reaction media. The current strategy was also applied in asymmetric Michael addition leading to a catalytic system with good activity and stereoselectivity. [Copyright &y& Elsevier]

Dy(OTf)3 immobilized in ionic liquids was found to be an efficient catalytic system for the reactions of indole with aldehydes/ketones or imines. Enhanced activity was observed. The use of ionic liquids as the reaction media allows facile separation and recycling of the catalyst. [Copyright &y& Elsevier]

The proline catalyzed aldol reactions of nitrobenzaldehydes with various ketones in aqueous anionic micelles were investigated. Both the selectivities and reaction yields were observed to be higher than those of the corresponding reactions in organic solvents. A reaction mechanism is proposed that is somewhat different from that in organic solvents. [Copyright &y& Elsevier]

The article presents chemical equations for the article "Asymmetric Sulfa-Michael Addition to α-Substituted Vinyl Ketones Catalyzed by Chiral Primary Amine" by L. Zhang and others published in "Organic Letters" in 2014.