Nickel‐Catalyzed Coupling of Thiomethyl‐Substituted 1,3‐Benzothiazoles with Secondary Alkyl Grignard Reagents

Abstract

Synthetic methods: The Ni‐catalyzed alkylation of 2‐(methylthio)benzothiazoles through CS bond cleavage is reported. Reactions with various secondary alkyl nucleophiles proceeded efficiently in the presence of 1,3‐butadiene as an additive. This reaction was proposed to proceed by σ‐bond metathesis between the thioether and a bis(π‐allyl)nickel complex or by an addition/elimination mechanism involving the CN double bond of the benzothiazoles (see scheme).

Ni-Catalyzed Dimerization and Hydroperfluoroarylation of 1,3-Dienes

“…As reported by Wilke and co-workers, triphenylphosphine coordinates with complex B to form complex F as a resting state of the present reaction. Complexation of B with an alkyl Grignard reagent leads to the formation of anionic complex C , ,− which selectively reacts with perfluoroarene 1 at the γ-carbon of the σ-allyl group. Reductive elimination of the alkyl and allyl groups of Ni in complex D most likely generates alkylperfluoroarylation product 5 ; however, this is a slow process, and the more facile β-hydrogen elimination proceeds selectively giving rise to three-component coupling product 3 via hydride complex E .…”

Co-Catalyzed Cross-Coupling of Alkyl Halides with Tertiary Alkyl Grignard Reagents Using a 1,3-Butadiene Additive

“…Previously we reported on the development of the Ni-, Pd-, and Cu-catalyzed cross-coupling reaction of alkyl (pseudo)halides with alkyl Grignard reagents utilizing unsaturated hydrocarbon additives. ,, Here we report a Co/LiI/1,3-butadiene catalytic system as a new route to alkyl–alkyl cross-coupling reactions, , in which alkyl halides are successfully coupled with tertiary alkyl Grignard reagents to afford branched alkanes including quaternary carbon centers.…”

Practical, Modular, and General Synthesis of Benzofurans through Extended Pummerer Annulation/Cross‐Coupling Strategy

“…Chemie strategy, we developed new Kumada-Tamao-Corriu conditions for bulky thioethers [7,8,19] [6] The reaction of 4 e with the 3-methoxy-4-siloxyphenylzinc reagent [21] provided TBS-protected E5 (TBS) in 57 % yield, and was smoothly deprotected with TBAF to give E5 in 96 % yield. Finally, we performed modular and tailor-made syntheses of multisubstituted difurans because substituents on the furan cores significantly alter their photophysical properties.…”

“…Chemie strategy, we developed new Kumada-Tamao-Corriu conditions for bulky thioethers [7,8,19] catalyzed by [IPrNiCl 2 -(PPh 3 )]. [20] Treatment of 4 e with a Grignard reagent in toluene at 60 8C for 12 h in the presence of the [IPrNiCl 2 -(PPh 3 )] catalyst furnished Eupomatenoid-3 (E3) in 79% yield.…”

“…KDMs having perfluorinated substituents also reacted similarly (entries 10 and 11). The scope of substituted phenols was also studied and showed high functional-group compatibility (entries [12][13][14][15][16][17][18][19][20]. Phenols having halogen, boron, electron-withdrawing, or electron-donating groups smoothly reacted (entries [12][13][14][15].…”