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A highly enantioselective [4+2] annulation with respect to allenoates and 3-olefinic oxindoles catalyzed by Lewis base was reported, which proved to be an efficient way to synthesize chiral dihydropyran-fused indoles. The cycloaddition products were generally obtained in high yields (up to 98%) with very good enantioselectivities (up to 94% enantiomeric excess).

A highly enantioselective [4 + 2] cycloaddition of allenoates with 2-olefinic benzofuran-3-ones catalyzed by (DHQD)2AQN, which allowed the synthesis of optically active dihydropyran-fused benzofurans, was developed.

Asymmetric olefin isomerization of β,γ- to α,β-unsaturated butenolides catalyzed by novel cinchona alkaloid derivatives was investigated in-depth using density functional theory (M05-2x and B2PLYP-D). Three possible mechanistic scenarios, differing in the binding modes of the substrate to the catalyst, have been evaluated. Computations revealed that both the protonated quinuclidine and the 6'-OH of catalysts may act as the proton donor in the stereocontrolling step. Variation of the catalytic activity and enantioselectivity by tuning the electronic effect of catalyst was well reproduced computationally. It suggested that, for certain acid-base bifunctional chiral catalysts, the acid-base active sites of catalysts may interconvert and give new catalyst varieties of higher activity and selectivity. In addition, the noncovalent interactions in the stereocontrolling transition-state structures were identified, and their strength was quantitatively estimated. The weak nonconventional C-H···O hydrogen-bonding interactions were found to be crucial to inducing the enantioselectivity of the cinchona alkaloid derivatives catalyzed asymmetric olefin isomerization. The computational results provided further theoretical evidence that the rate-limiting step of this bioinspired organocatalytic olefin isomerization is inconsistent with that of the enzyme catalyzed olefin isomerization.

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).

The current work reports an organocatalytic strategy for the asymmetric catalysis of chiral benzofuran-2(3H)-ones bearing 3-position all-carbon quaternary stereocenters. Accordingly, highly enantioselective Michael addition reactions of 3-substituted benzofuran-2(3H)-ones to nitroolefins have been developed by utilizing a bifunctional tertiary-amine thiourea catalyst. The reactions accommodate a number of nitroolefins and 3-substituted benzofuran-2(3H)-ones to give the desired chiral benzofuran-2(3H)-one products with moderate to excellent yields (up to 98%) and moderate to very good selectivities (up to 19 : 1 dr and up to 91% ee). Theoretical calculations using the DFT method on the origin of the stereoselectivity were conducted. The effect of the nitroolefin substituent position on the stereoselectivity of the Michael addition reaction was also theoretically rationalized.

Chiral amine and polyoxometalate (POM) acids were combined to give highly efficient, stereoselective, and recoverable enamine-based catalysts. Less than 1 mol % of chiral amine loading was sufficient for good catalytic activity, and the catalyst could be recovered and reused 6 times with unchanged enantioselectivity and slightly decreased activity.

A new polysiloxane-supported NAD(P)H model, 1-benzyl-1,4-dihydronicotinamide, was designed and synthesized, which can efficiently reduce many activated olefins under mild conditions. The most advantageous features of this new polysiloxane-supported reductant are (i) easy workup and separation of the reaction products and (ii) good potential for recycling use of the reductant, which makes this new polysiloxane-supported NAD(P)H model a promising alternative both in research laboratories and in industrial processes.

Introduction of the trifluoromethyl (CF3) group into organic compounds has garnered substantial interest because of its significant role in pharmaceuticals and agrochemicals. Here, we report a hydroxylamine‐mediated radical process for C(sp2)−H trifluoromethylation of terminal alkenes. The reaction shows good reactivity, impressive E/Z selectivity (up to >20 : 1), and broad functional group compatibility. Expansion of this approach to perfluoroalkylation and late‐stage trifluoromethylation of bioactive molecules demonstrates its promising application potential. Mechanistic studies suggest that the reaction follows a radical addition and subsequent elimination pathway. [ABSTRACT FROM AUTHOR]

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]

The article discusses a study on an asymmetric binary acid catalysis of hetero-Diels-Alder reaction of simple olefins with electron-deficient enones. It says that achieving a catalytic asymmetric version with simple olefins remains elusive despite the advances in Diels-Alder chemistry. It mentions the examination of Lewis acids and chiral phosphoric acids in the model reaction of styrene 2a with ketoester 3a.

Acetylacetonatoboron difluoride (AABF[sub 2]) and oxalate (AABO) undergo cycloaddition from their singlet excited state with cyclic and terminal olefins to give stereospecific but non-regiospecific products; the latter oxalate reacted slightly faster than the former difluoride. A conjugated diene, 1,3-cyclooctadiene, and methyl substituted benzenes also reacted similarly but with slower rates owing to electron transfer at the encounter stage. The resulting radical ion pairs may undergo radical ion type reactions and/or reverse electron transfer, which leads to the partial waste of the photoenergy. For the same reasons, the reaction occurs more efficiently in non-polar solvents, such as ether, dioxane and methylene chloride than in acetonitrile. [ABSTRACT FROM AUTHOR]

A simple, efficient, and highly atom economic haloamidation of simple alkenes has been developed, using AgBF4or InBr3/AgBF4(1:3) as catalyst and N-halophthalimide as both nitrogen and halogen source. A broad range of olefins can be applied to afford vicinal haloamines in good yields and with high regioselectivity and diastereoselectivity. [ABSTRACT FROM AUTHOR]

The photoreaction of N-bromosaccharin with a range of alkenes leads to a mixture of bromoamide (V) and bromoether (VI). [ABSTRACT FROM AUTHOR]

Anunprecedented intramolecular conjugate addition of simple alkenesto α,β-unsaturated carbonyl compounds has been developed.A simple Lewis acid such as Cu(OTf)2was found to effectivelycatalyze the reaction, and six- and five-membered cyclic productswere obtained in moderate to high yields. [ABSTRACT FROM AUTHOR]

About 20 target ring structures are prepared from 3-olefinic oxindoles. [ABSTRACT FROM AUTHOR]

The exchange of the metal ion from In(III) to Sc(III) in a binary acid catalyst leads to a switch in the diastereoselectivity of [4 + 2] cycloadditions. [ABSTRACT FROM AUTHOR]