A general asymmetric deconstructive alkynylation of cyclic oximes with terminal alkynes was reported using copper/ chiral cinchona alkaloid-based N,N,P-ligand catalysts and used to produce more than 60 examples of enantioenriched γand δalkynyl nitriles in a highly functional group-compatible manner. A wide variety of low-cost terminal alkynes and easily available cyclic oximes with substituent diversity were found to be well tolerated with the current asymmetric transformation with good functional group tolerance. The resulting chiral alkynyl nitriles are intermediates, which could be converted into skeletally diverse chiral molecules, including δ-alkynyl amides, ε-alkenyl carbamate, and ζ-keto nitrile, under suitable reaction conditions.
A new electrochemically induced three-component annulation-halosulfonylation of 1,6-enynes has been developed for stereoselective synthesis of 33 examples of 1-indanones with generally good yields under environmentally benign conditions.
Tunable halofluoroalkylation and hydrofluoroalkylation of 1,6‐enynes were first reported by switching between copper‐catalysis and photocatalysis, leading to the atom‐economic and highly stereoselective protocols toward functionalized 1‐indenones with moderate to good yields. Copper‐catalysis enabled the concomitant incorporation of two important fluoroalkyl and halo functionalities into 1‐indenone skeleton, in which fluoroalkyl bromides were transformed into (E)‐1‐indenones as a major stereoisomer while fluoroalkyl iodides oriented complete Z‐selectivity to access (Z)‐1‐indenones. Specifically, photocatalysis allowed hydrofluoroalkylation of 1,6‐enynes to access fluoroalkylated (Z)‐1‐indenones under mild conditions, in which THF behaved as a hydrogen source. These two approaches feature remarkable compatibility with a wide variety of 1,6‐enynes and fluoroalkyl halides and excellent atomic utilization.magnified image
Catalytic asymmetric hydrofunctionalization
of alkenes is a well-established
method with which to construct complex C(sp3)-enriched
molecules with central chirality. In contrast, the use of catalytic
asymmetric hydrofunctionalization of abundant alkyne substrates to
produce valuable multisubstituted alkenes with axial chirality remains
largely unexplored. Here, we report a general procedure of this type
catalyzed by abundant Ni(II) salts and employing a structurally simple
chiral PyrOx ligand. A wide variety of structurally diverse atropisomeric
chiral styrenes have been obtained from hydroarylation of alkynes
with high efficiency, complete Z-selectivity, and
excellent enantioselectivity.
A concise copper catalysis strategy for the addition−cyclization of cyclic oxime esters across 1,6-enynes with high stereoselectivity to generate 1-indanones bearing an allcarbon quaternary center is reported. In this process, singleelectron reduction of cyclic oxime esters enables deconstructive carbon−carbon cleavage to provide a key cyanopropyl radical poised for the addition−cyclization. This reaction is redox-neutral, exhibits good functional group compatibility, and features 100% atomic utilization. This process driven by copper catalyst makes readily available cyclic oxime esters as bifunctional reagents to demonstrate convergent synthesis.
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