Nickel-catalyzed asymmetric arylative cyclization of N-alkynones: Efficient access to 1,2,3,6-tetrahydropyridines with a tertiary alcohol

Enantioselective Synthesis of 3-Hydroxy-2-Oxindoles via Ni-Catalyzed Asymmetric Addition of Aromatic Bromides to α-Ketoamides

Nickel-catalyzed asymmetric intramolecular addition of aryl halides to α-ketoamides has been achieved to afford chiral 3-substituted-3-hydroxy-2-oxindoles in excellent yields and high enantioselectivities (up to 99 % yield and 98 % ee), which provides efficient access to valuable molecules containing 3-hydroxy-2-oxindole core. The gram-scale reaction proved the potential utility of the methodology.

Nickel-Catalyzed Reductive anti-Arylative Cyclization of Alkynyl Enones with Aryl Halides

A nickel-catalyzed reductive anti-arylative cyclization of alkynyl enones with aryl halides has been developed. The reaction avoids the use of stoichiometric organometallic reagents and has a broad reaction scope and high functional group tolerance. This method offers an efficient way to access a variety of synthetically useful carbocycles that are widely found in many natural products and biologically active molecules.

Palladium(0)-Catalyzed Anti-Selective Addition-Cyclizations of Alkynyl Electrophiles

Palladium(0)/monophosphine complexes catalyze anti-selective alkylative, arylative, and alkynylative cyclizations of alkynyl electrophiles with organometallic reagents. The remarkable anti-selectivity results from novel oxidative addition, that is, the nucleophilic attack of electron-rich palladium(0) on the electrophile across the alkyne followed by transmetalation and reductive elimination ("anti-Wacker"-type cyclization). With regard to 5-alkynals, triphenylphosphine (PPh3 )-ligated palladium(0) catalyzes the cyclization of terminal alkynes and conjugated alkenyl- or alkynyl-substituted ones to afford 2-cyclohexen-1-ol and 2-alkylidene-cyclopentanol derivatives, respectively. For 6-alkyl- or 6-aryl-5-alkynals, the cyclization does not proceed with the palladium/PPh3 catalyst; however, it does proceed with palladium/tricyclohexylphosphine (PCy3 ), to yield the former products predominantly. Remarkably, the latter catalyst completely switches the regioselectivity in the cyclization of the conjugated diyne-aldehydes. Notably, palladium/PPh3 -catalyzed cyclizations also proceed with other organometallics or even without them.

Iridium-Catalyzed Chemoelective Asymmetric Hydrogenation of Conjugated Enones with Ferrocene-Based Multidentate Phosphine Ligands

A series of novel and readily prepared ferrocene-based multidentate phosphine ligands (f-PNNO) have been developed and successfully used in iridium-catalyzed enantioselective 1,2-reduction of ,-unsaturated ketones, delivering chiral allylic alcohols in...