A straightforward and efficient approach to structurally diverse and synthetically useful ring-fluorinated 4H-pyrans via a simple base-mediated cascade reaction of readily available trifluoromethylated alkenes with 1,3-dicarbonyl compounds was developed. The key events of this reaction involve two consecutive C-F substitutions under very mild conditions.

A novel phosphine-catalyzed, highly enantioselective umpolung addition of trifluoromethyl ketimines to Morita-Baylis-Hillman carbonates was developed and it provides facile access to optically active trifluoromethyl amines with a chiral tertiary stereocenter under mild reaction conditions. The salient features of this reaction include general substrate scope, mild reaction conditions, good yields, high enantioselectivity, ease of scale-up to gram scale, and further transformations of the products.

An organocatalytic asymmetric formal [3 + 2] cycloaddition of enynones with N-hydroxylamines has been described. A newly designed multifunctional organocatalyst was found to be highly effective, and the method allowed the synthesis of a variety of 2,3-dihydroisoxazoles in good yields with excellent enantioselectivity.

Scheme 2. Va rious b-keto ester compounds.R eactions were carried out with 0.2 mmol of 1,0 .6 mmolo f2 and 20 mol% catalyst at room temperature.Isolated yields.Scheme 3. X-ray crystals tructure of (R)-3ag.Scheme 4. Control experiments.

Catalytic enantioselective Cu-B(pin) (pin = pinacolato) addition to N-heteroaryl-substituted alkenes followed by protonation promoted by phosphine-Cu complexes is presented. The resulting alkylboron products that contain a N-heteroaryl moiety are afforded in up to 97% yield and 99:1 enantiomeric ratio. The highly versatile C-B(pin) bond can be converted to a range of useful functional groups, delivering a variety of enantiomerically enriched building blocks that are otherwise difficult to access. The utility of this method is further demonstrated by application to a fragment synthesis of biologically active molecule U-75302. Preliminary mechanistic studies revealed that the adjacent N atom of the heterocycles plays a unique role in high reactivity and enantioselectivity.

Catalytic enantioselective conjugate additions with easily accessible alkenylboronic acid pinacol esters as nucleophiles promoted by chiral copper complexes of Nheterocyclic carbenes are presented. These processes constitute an unprecedented instance of conjugate additions of a variety of functionalized alkenyl groups and afford desired products that are otherwise difficult to access in up to 98% yield and 99.5:0.5 enantiomeric ratio. The origins of ligandcontrolled enantioselectivity are elucidated with density functional theory (DFT) calculations.

A novel phosphine-catalyzed, highly enantioselective umpolung addition of trifluoromethyl ketimines to Morita-Baylis-Hillman carbonates was developed and it provides facile access to optically active trifluoromethyl amines with a chiral tertiary stereocenter under mild reaction conditions. The salient features of this reaction include general substrate scope, mild reaction conditions, good yields, high enantioselectivity, ease of scale-up to gram scale, and further transformations of the products.

A triphenylphosphine (PPh3)‐catalyzed, regioselective and stereoselective hydrohalogenation reaction of 2‐(1‐alkynyl)‐2‐alken‐1‐ones with metal halides in the presence of acetic acid is described, furnishing functionalized 3,4‐disubstituted 2‐halo‐1,3‐dienes in moderate to good yields with high stereoselectivity and regiospecificity. The simple execution, mild conditions and the potential utilization of the products make this protocol attractive.magnified image