Nickel-catalyzed coupling reaction of alkyl halides with aryl Grignard reagents in the presence of 1,3-butadiene: mechanistic studies of four-component coupling and competing cross-coupling reactions.

We describe the mechanism, substituent effects, and origins of the selectivity of the nickel-catalyzed four-component coupling reactions of alkyl fluorides, aryl Grignard reagents, and two molecules of 1,3-butadiene that affords a 1,6-octadiene carbon framework bearing alkyl and aryl groups at the 3- and 8-positions, respectively, and the competing cross-coupling reaction. Both the four-component coupling reaction and the cross-coupling reaction are triggered by the formation of anionic nickel complexes, which are generated by the oxidative dimerization of two molecules of 1,3-butadiene on Ni(0) and the subsequent complexation with the aryl Grignard reagents. The C-C bond formation of the alkyl fluorides with the γ-carbon of the anionic nickel complexes leads to the four-component coupling product, whereas the cross-coupling product is yielded nucleophilic attack of the Ni center toward the alkyl fluorides.

Co-Catalyzed Cross-Coupling Reaction of Alkyl Fluorides with Alkyl Grignard Reagents.

The cross-coupling reaction of unactivated alkyl fluorides with alkyl Grignard reagents by a CoCl/LiI/1,3-pentadiene catalytic system is described. The present reaction smoothly cleaved C-F bonds under mild conditions and achieved alkyl-alkyl cross-coupling even when sterically hindered tertiary alkyl Grignard reagents were employed. Since alkyl fluorides are inert toward many reagents and catalytic intermediates, the use of the present reaction enables a new multistep synthetic route to construct carbon frameworks by combining conventional transformations.

Fe-Catalyzed Cross-Coupling Reaction of Vinylic Ethers with Aryl Grignard Reagents.

Iron-catalyzed cross-coupling reaction of vinylic ethers with aryl Grignard reagents is described. The reaction proceeded at room temperature with catalytic amounts of an iron salt without the aid of costly ligands and additives. In this catalytic system, vinylic C-O bonds were preferentially cleaved over aromatic C-O bonds of aryl ethers or aryl sulfonates.

Multicomponent Coupling Reaction of Perfluoroarenes with 1,3-Butadiene and Aryl Grignard Reagents Promoted by an Anionic Ni(II) Complex.

An anionic Ni complex was isolated and its structure determined by X-ray crystallography. With such an anionic complex as a key intermediate, a regio- and stereoselective multicomponent coupling reaction of perfluoroarenes, aryl Grignard reagents, and 1,3-butadiene in a 1:1:2 ratio was achieved, resulting in the formation of 1,6-octadiene derivatives containing two aryl groups, one from the perfluoroarene and the other from the aryl Grignard reagent, at the 3- and 8-positions, respectively.

Nickel-Catalyzed Dimerization and Alkylarylation of 1,3-Dienes with Alkyl Fluorides and Aryl Grignard Reagents.

In the presence of a nickel catalyst, 1,3-butadiene undergoes selective dimerization and alkylarylation with alkyl fluorides and aryl Grignard reagents to give 1,6-octadienes with alkyl and aryl groups at the 3- and 8-positions, respectively, by the consecutive formation of three carbon-carbon bonds. The formation of an anionic nickel complex plays an important role in forming C-C bonds with alkyl fluorides.

Copper-Catalyzed Regioselective Hydroalkylation of 1,3-Dienes with Alkyl Fluorides and Grignard Reagents.

Copper complexes generated in situ from CuCl2, alkyl Grignard reagents, and 1,3-dienes play important roles as catalytic active species for the 1,2-hydroalkylation of 1,3-dienes by alkyl fluorides through C-F bond cleavage. The alkyl group is introduced to an internal carbon atom of the 1,3-diene regioselectively, thus giving rise to the branched terminal alkene product.

Copper-catalyzed alkyl-alkyl cross-coupling reactions using hydrocarbon additives: efficiency of catalyst and roles of additives.

Cross-coupling of alkyl halides with alkyl Grignard reagents proceeds with extremely high TONs of up to 1230000 using a Cu/unsaturated hydrocarbon catalytic system. Alkyl fluorides, chlorides, bromides, and tosylates are all suitable electrophiles, and a TOF as high as 31200 h(-1) was attained using an alkyl iodide. Side reactions of this catalytic system, i.

Diarylrhodates as promising active catalysts for the arylation of vinyl ethers with Grignard reagents.

Anionic diarylrhodium complexes, generated by reacting [RhCl(cod)]2 with 2 equiv of aryl Grignard reagents, were found to be effective active catalysts in cross-coupling reactions of vinyl ethers with aryl Grignard reagents, giving rise to the production of vinyl arenes. In this catalytic system, vinyl-O bonds were preferably cleaved over Ar-O or Ar-Br bonds. A lithium rhodate complex was isolated, and its crystal structure was determined by X-ray crystallography.

Co-catalyzed cross-coupling of alkyl halides with tertiary alkyl Grignard reagents using a 1,3-butadiene additive.

The cobalt-catalyzed cross-coupling of alkyl (pseudo)halides with alkyl Grignard reagents in the presence of 1,3-butadiene as a ligand precursor and LiI is described. Sterically congested quaternary carbon centers could be constructed by using tertiary alkyl Grignard reagents. This reaction proceeds via an ionic mechanism with inversion of stereochemistry at the reacting site of the alkyl halide and is compatible with various functional groups.

Pd-catalyzed regioselective iminothiolation of alkynes: a remarkable effect of the CF3 group of iminosulfides.

Pd-catalyzed iminothiolation of alkynes took place to afford 4-SR substituted 1-azadienes regioselectively.

Transition-metal-catalyzed regioselective aroyl- and trifluoro-acetylthiolation of alkynes using thioesters.

Intermolecular CO-retained carbothiolation of alkynes using thioesters took place to afford beta-SR substituted enone derivatives; the choice of catalyst (Pd(dba)(2)-dppe) and the introduction of a CF(3) group into the thioesters are the key to achieving the transformation.

Palladium-catalyzed selenoacylation of allenes leading to the regioselective formation of functionalized allyl selenides.

Palladium-catalyzed regio- and stereoselective selenoacylation of allenes with selenol esters proceeded to produce functionalized allyl selenides with the acyl moiety at the inner carbon and the SePh group at the terminal carbon in high yields. A mechanism accounting for the observed regio- and stereoselectivities is proposed based on the results of DFT calculations.

Platinum-catalyzed intramolecular vinylchalcogenation of alkynes with beta-phenylchalcogeno conjugated amides.

Platinum-catalyzed intramolecular vinylthiolation and -selenation of internal alkynes with vinylchalcogenides 1 having a carbamoyl group on cis-beta-position of vinyl moiety was developed. The conjugated six-membered lactam framework 2 was constructed in high yields. Density functional theory calculations for alkyne insertion processes suggest seven-membered platinacycle 3 is a kinetically favored intermediate of this catalytic system.

One-pot syntheses of 2,3-dihydrothiopyran-4-one derivatives by Pd/Cu-catalyzed reactions of alpha,beta-unsaturated thioesters with propargyl alcohols.

2,3-Dihydrothiopyran-4-one derivatives were readily prepared by Pd/Cu-catalyzed reactions between alpha,beta-unsaturated thioesters and propargyl alcohols in the presence of bases. Of note, both carbon-sulfur bonds were cleaved as a result of the single procedure.

Cu-catalyzed regioselective carbomagnesiation of dienes and enynes with sec- and tert-alkyl Grignard reagents.

The carbomagnesiation of dienes and enynes with sec- and tert-alkyl Grignard reagents has been achieved by using copper salts as catalysts.

Platinum-catalyzed regio- and stereoselective arylthiolation of internal alkynes.

Unsymmetrical internal alkynes such as ethyl phenylpropiolate (2b) successfully underwent Pt-catalyzed decarbonylative arylthiolation by thioesters. The regio- and stereoselective insertion of 2b into an S-Pt bond was confirmed by reaction with a platinum complex with an S-Pt-Cl framework.

Cross-coupling of alkyl halides with Grignard reagents using nickel and palladium complexes bearing eta(3)-allyl ligand as catalysts.

The cross-coupling of Grignard reagents with alkyl bromides and tosylates has been achieved by the use of eta(3)-allylnickel and eta(3)-allylpalladium complexes as catalysts.

"Beta-cis-SAr effect" on decarbonylation from alpha,beta-unsaturated acyl and aroyl complexes.

Lone pair of heteroatom located at the beta-cis position in alpha,beta-unsaturated acyl and aroyl group 10 metal complexes dramatically facilitated the stoichiometric and catalytic decarbonylation reactions.

cis-to-trans isomerization promoted by pyridine as a crucial step for the selective preparation of trans-Pt(SAr)(Cl)(PAr'3)2.

The general strategy for the syntheses of trans-Pt(SAr)(Cl)(PAr'3)2 (1) (Ar = Ph, C6H4-2-Me, C6H4-3-OMe C6H4-2-F, etc.; Ar' = Ph, C6H4-4-OMe, C6H4-4-Me, and C6H4-4-CF3) by the reaction of cis-PtCl2(PAr'3)2 with ArSH has been developed. The mechanistic investigation suggested that isomerization of cis-1 into trans-1 promoted by the combined use of C6H6 as a solvent and pyridine as a base was the key to the successful preparation of 1.

Palladium-catalyzed intramolecular selenocarbamoylation of alkynes with carbamoselenoates: formation of alpha-alkylidene-beta-lactam framework.

Pd-catalyzed intramolecular selenocarbamoylation of alkynes leading to alpha-alkylidene-beta-lactams was developed. This reaction can be applied to thiocarbamoylation and to the synthesis of delta- and epsilon-lactams and a cyclobutanone.

The Pt-catalyzed carboselenation of alkynes by selenoesters.

[reaction: see text] The Pt-catalyzed carboselenation of terminal alkynes with selenoesters provided vinylselenides regio- and stereoselectively in moderate yields.