Lewis-acid catalysts such as AlMe3, AlMe2Cl, and BPh3 significantly improve the efficiency of the nickel-catalyzed arylcyanation of alkynes. Electron-rich aryl cyanides, which exhibit poor reactivity in the absence of Lewis acids, readily undergo the arylcyanation reaction under the newly disclosed conditions. Excellent chemoselectivity is observed for aryl cyanides having a chloro and bromo group, allowing a single-step preparation of the synthetic intermediate of P-3622, a squalene synthetase inhibitor. Moreover, the first examples of alkenyl- and alkylcyanation of alkynes have been achieved by the nickel−Lewis acid dual catalyst.

A Dramatic Effect of Lewis-Acid Catalysts on Nickel-Catalyzed Carbocyanation of Alkynes

An efficient Cu-catalyzed protocol for enantioselective addition of a dimethylphenylsilanyl group to a wide range of cyclic and acyclic unsaturated ketones, esters, acrylonitriles, and alpha,beta,gamma,delta-dienones is disclosed. Reactions are performed in the presence of 1-2 mol % of commercially available and inexpensive CuCl, a readily accessible monodentate imidazolinium salt, and commercially available (dimethylphenylsilyl)pinacolatoboron. Cu-catalyzed enantioselective conjugate additions proceed to completion within only 2 h to afford the desired silanes in 87-97% yield and 90:10-99:1 enantiomeric ratio (er). Use of a proton source (e.g., MeOH) is not required; accordingly, synthetically versatile alpha-silyl boron enolates can be obtained. The special utility of the present protocol, in comparison with the related catalytic enantioselective aldol and boronate conjugate additions, is discussed and illustrated through various functionalizations of the enantiomerically enriched beta-silylcarbonyls.

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Enantioselective Conjugate Silyl Additions to Cyclic and Acyclic Unsaturated Carbonyls Catalyzed by Cu Complexes of Chiral N-Heterocyclic Carbenes

Catalytic enantioselective diboration, disilation and silaboration: new opportunities for asymmetric synthesis

Enantioselective formal hydration of α,β-unsaturated acceptors: asymmetric conjugate addition of silicon and boron nucleophiles.

Cyanoformates and cyanoformamides are found to add across alkynes by nickel/Lewis acid (LA) cooperative catalysis to give beta-cyano-substituted acrylates and acrylamides, respectively, in highly stereoselective and regioselective manners. The resulting adducts serve as versatile synthetic building blocks through chemoselective transformations of the ester, amide, and cyano groups as demonstrated by the synthesis of typical structures of beta-cyano ester, beta-amino nitrile, gamma-lactam, disubstituted maleic anhydride, and gamma-aminobutyric acid. The related reactions of cyanoformate thioester and benzoyl cyanide, on the other hand, are found to add across alkynes with decarbonylation in the presence of a palladium/LA catalyst.

Nickel/Lewis Acid-Catalyzed Cyanoesterification and Cyanocarbamoylation of Alkynes

In the presence of a catalytic amount of Me(3)SiOTf and palladium(0), the addition of disilane to alpha,beta-unsaturated carbonyl compounds proceeds under very mild conditions via eta(3)-siloxyallylpalladium generated by the reaction of enone, enal, or aromatic aldehyde with palladium and Me(3)SiOTf.

Palladium/Me3SiOTf-Catalyzed bis-silylation of α, β-unsaturated carbonyl compounds without involving oxidative addition of disilane

The reaction of a substitutionally labile dipalladium(I) complex [Pd2(CH3CN)6][BF4]2 with isoprene or 1,3-butadiene in acetonitrile afforded [Pd2(μ-η3:η1-C5H8)(CH3CN)5][BF4]2 or [Pd2(μ-η3:η1-C4H6)(...

Sadayuki Tomiyasu

Papers

Palladium/Me3SiOTf-Catalyzed bis-silylation of α, β-unsaturated carbonyl compounds without involving oxidative addition of disilane

Dinuclear Addition of the Pd–Pd Moieties to 1,3-Dienes

Palladium/Me3SiOTf‐Catalyzed Bis‐silylation of α,β‐Unsaturated Carbonyl Compounds Without Involving Oxidative Addition of Disilane.