Yoshiaki Nakao 교수

Much attention has been paid to the cross-coupling reaction of organosilicon compounds due to their stability, non-toxicity, and natural abundance of silicon. In addition, the silicon-based cross-coupling has many advantages over other cross-coupling protocols. Successful examples of the silicon-based cross-coupling reaction are reviewed, focusing especially on the advances made in the last decade. Having had a number of highly effective palladium catalysts developed mainly for other cross-coupl

Direct C-4-selective addition of pyridine across alkenes and alkynes is achieved for the first time by nickel/Lewis acid cooperative catalysis with an N-heterocyclic carbene ligand. A variety of substituents on both alkenes and pyridine are tolerated to give linear 4-alkylpyridines in modest to good yields. The addition across styrene, on the other hand, gives branched 4-alkylpyridines. A single example of C-4-selective alkenylation is also described.

The C-2 selective alkenylation of pyridine derivatives is achieved with a catalyst consisting of nickel and Lewis acid. Use of diorganozinc compounds as the Lewis acid catalyst gives C-2 monoalkenylation products, whereas AlMe3 changes the reaction course to afford C-2 dienylated products, which are derived from double insertion of alkynes into the C(2)−H bond. The reaction demonstrates a broad substrate scope and proceeds with high chemo-, regio-, and stereoselectivities under mild conditions c

Nickel/P(c-C(5)H(9))(3) (PCyp(3)) catalyst effects the addition reactions of fluoroarenes across alkynes, 1,3-dienes, and vinylarenes via the activation of C-H bonds over C-F bonds. The acidic C-H bonds located ortho to fluorine are exclusively activated to afford a range of alkenylated and alkylated fluoroarenes.

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

Nickel complexes having a bulky tri(sec-alkyl)phosphine ligand catalyze hydroheteroarylation of alkynes at 35 degrees C. Selective activation of an Ar-H bond over an Ar-CN bond of N-protected 3-cyanoindoles is achieved by a proper choice of ligand and/or an N-protecting group. The catalysis is applicable to a diverse range of heteroarenes to afford cis-hydroheteroarylation products in highly chemo- and stereoselective manners. Excellent regioselectivity is observed with unsymmetrical alkynes to

An alternative to pyridine: Pyridine-N-oxides undergo direct CH activation and add across alkynes under mild nickel catalysis to afford (E)-2-alkenylpyridine-N-oxides in modest to good yields with high selectivity. Subsequent deoxygenation and deoxygenative functionalization proceed smoothly to give a wide variety of 2-substituted pyridines. PCyp3=tricyclopentylphosphine, cod=cyclooctadiene.

A catalyst system derived from nickel and cocatalytic AlMe2Cl effects the intramolecular arylcyanation of alkenes. The reaction takes place in an exclusive exo-dig manner to give a wide range of nitriles having a benzylic quaternary carbon in good yields. Detailed investigations are described on the scope and mechanism as well as preliminary results on the asymmetric version of the reaction to provide novel access to chiral quaternary stereocenters.

Nickel catalysts derived from bis(1,5-cyclooctadiene)nickel [Ni(cod)(2)] and trialkylphosphines effect hydroarylation of alkynes through functionalization of C-H bonds of arenes including benzo-fused five-membered heteroarenes, pyridine-N-oxides, pyridines, 2-pyridones, and perfluoroarenes. The reactions proceed with excellent stereo- and regioselectivity to give disubstituted arylethenes in good yields. Use of Lewis acid (LA) co-catalysts is crucial for success in reactions of imidazoles, pyrid

A nickel catalyst coordinated by trimethylphosphine is found to effect the addition reaction of Ar-CN bonds in aromatic nitriles across alkynes to give rise to various beta-arylalkenenitriles.

Regioselective alkenylation and alkylation of 2-pyridone derivatives are achieved through inter- and intramolecular insertion of alkynes, 1,3-dienes, and alkenes into the C(6)-H bond by nickel/AlMe(3) catalysis. Coordination of the heterocycles to the Lewis acid cocatalyst through their basic carbonyl oxygen is considered to be responsible for the regioselective activation of the C-H bonds, probably through oxidative addition to nickel(0).

The direct functionalization of pyridine and related azine derivatives through carbon-carbon bond-forming reactions is reviewed. Various transformations that use a variety of transition-metal catalysts are covered, including alkylation, alkenylation, arylation, and acylation. In addition to the conventionally observed C2-selectivity for these transformations, recent developments involve selective introduction of newly formed carbon-carbon bonds to the C3- and C4-positions of pyridine and azine n

We report herein the iridium-catalyzed meta-selective C-H borylation of benzamides by using a newly designed 2,2'-bipyridine (bpy) ligand bearing an alkylaluminum biphenoxide moiety. We also demonstrate the iridium-catalyzed C3-selective C-H borylation of pyridine with a 1,10-phenanthroline (Phen) ligand bearing an alkylborane moiety. It is proposed that the Lewis acid-base interaction between the Lewis acid moiety and the aminocarbonyl group or the sp²-hybridized nitrogen atom accele

In the presence of a nickel/carbene catalyst, the hydroheteroarylation of vinylarenes with indoles, benzimidazoles, and analogues affords exclusively 1-aryl-1-heteroarylethanes.

Alkenyl- and aryl[2-(hydroxymethyl)phenyl]dimethylsilanes, highly stable tetraorganosilicon reagents, are found to react with aryl and alkenyl iodides in the presence of a palladium catalyst and K2CO3 as a base, significantly milder conditions compared with those ever reported for the silicon-based cross-coupling reactions. The reaction tolerates a wide range of functional groups, including silyl protectors, and allows a gram-scale synthesis to recover and reuse the silicon residue.