Cross-coupling Reactions Of Alkyl Halides Research Articles

Cobalt-Mediated Cross-Coupling Reactions of Primary and Secondary Alkyl Halides with 1-(Trimethylsilyl)ethenyl- and 2-Trimethylsilylethynylmagnesium Reagents

[reaction: see text] This paper describes cobalt-mediated cross-coupling reactions of alkyl halides with 1-(trimethylsilyl)ethenylmagnesium bromide and 2-(trimethylsilyl)ethynylmagnesium bromide, respectively. The cobalt system allows for employing secondary as well as primary alkyl halides as the substrates. The reactions offer facile formations of alkyl-alkenyl and alkyl-alkynyl bonds. The reaction mechanism would include single-electron transfer from a cobalt complex to alkyl halide to generate the corresponding alkyl radical. The cobalt system thus enables sequential radical cyclization/alkenylation and cyclization/alkynylation reactions of 6-halo-1-hexene derivatives.

Cobalt‐Catalyzed Cross‐Coupling Reactions of Alkyl Halides with Aryl Grignard Reagents and Their Application to Sequential Radical Cyclization/Cross‐Coupling Reactions.

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Cobalt(diamine)-Catalyzed Cross-coupling Reaction of Alkyl Halides with Arylmagnesium Reagents: Stereoselective Constructions of Arylated Asymmetric Carbons and Application to Total Synthesis of AH13205

A cobalt-diamine complex catalyzes the cross-coupling reactions of primary and secondary alkyl halides with aryl Grignard reagents. It is confirmed that oxidative addition of alkyl halide to cobalt proceeds via a radical process. Optically pure Ueno-Stork halo acetals undergo diastereoselective cross-coupling reactions, the products of which are transformed into optically active THF derivatives. A sequential radical cyclization/arylation reaction under cobalt catalysis provides extremely short access to a synthetic prostaglandin AH13205.

Synthesis of Cp*CH2PPh2 and its use as a ligand for the nickel-catalysed cross-coupling reaction of alkyl halides with aryl Grignard reagents

A new ligand, Cp*CH2PPh2 (Cp* = 1,2,3,4,5-pentamethyl-2,4-cyclopentadienyl), was prepared, and was used as a ligand for nickel-catalysed cross-coupling reaction of alkyl halides with aryl Grignard reagents, which nickel-phosphine complexes had never made possible.

New synthetic reactions catalyzed by cobalt complexes

Abstract Without suffering from β-elimination, cobalt complexes allow cross-coupling reactions of alkyl halides with Grignard reagents. A combination of a cobalt complex and trimethylsilylmethyl Grignard reagent effects Mizoroki-Heck-type reaction of alkyl halide with styrene, which conventional palladium catalysts have never made possible. Cobalt exhibits intriguing catalytic activities on hydrophosphination and allylzincation of alkynes. Silylmethylcobalt reagent is a powerful tool for the synthesis of highly silylated ethenes.

Cobalt-catalyzed cross-coupling reactions of alkyl halides with aryl Grignard reagents and their application to sequential radical cyclization/cross-coupling reactions

Reactions of alkyl halides with arylmagnesium bromides in the presence of cobalt(II)(diphosphine) complexes are discussed. Treatment of 1-bromooctane with phenylmagnesium bromide with the aid of a catalytic amount of CoCl 2(dppp) [DPPP=1,3-bis(diphenylphosphino)propane] yielded octylbenzene in good yield. The reaction mechanism would include single electron transfer from an electron-rich cobalt complex to alkyl halide to generate the corresponding alkyl radical. The mechanism was justified by CoCl 2(dppe)-catalyzed [DPPE=1,2-bis(diphenylphosphino)ethane] sequential radical cyclization/cross-coupling reactions of 6-halo-1-hexene derivatives that yielded benzyl-substituted cyclopentane skeletons.

Iron‐Catalyzed Chemoselective Cross‐Coupling of Primary and Secondary Alkyl Halides with Arylzinc Reagents.

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Cross‐Coupling Reaction of Alkyl Halides with Organometallic Reagents Using Transition‐Metal Catalysts

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Iron-Catalyzed Chemoselective Cross-Coupling of Primary and Secondary Alkyl Halides with Arylzinc Reagents

Functional-group-compatible cross-coupling reaction of alkyl halides with arylzinc reagents takes place under iron catalysis in the presence of TMEDA, producing a variety of aromatic compounds in good to excellent yield. The pronounced effect of a magnesium salt was found to be the key to the promotion of the iron-catalyzed coupling reaction.

Cobalt-catalyzed cross-coupling reactions of alkyl halides with allylic and benzylic Grignard reagents and their application to tandem radical cyclization/cross-coupling reactions.

Details of cobalt-catalyzed cross-coupling reactions of alkyl halides with allylic Grignard reagents are disclosed. A combination of cobalt(II) chloride and 1,2-bis(diphenylphosphino)ethane (DPPE) or 1,3-bis(diphenylphosphino)propane (DPPP) is suitable as a precatalyst and allows secondary and tertiary alkyl halides--as well as primary ones--to be employed as coupling partners for allyl Grignard reagents. The reaction offers a facile synthesis of quaternary carbon centers, which has practically never been possible with palladium, nickel, and copper catalysts. Benzyl, methallyl, and crotyl Grignard reagents can all couple with alkyl halides. The benzylation definitely requires DPPE or DPPP as a ligand. The reaction mechanism should include the generation of an alkyl radical from the parent alkyl halide. The mechanism can be interpreted in terms of a tandem radical cyclization/cross-coupling reaction. In addition, serendipitous tandem radical cyclization/cyclopropanation/carbonyl allylation of 5-alkoxy-6-halo-4-oxa-1-hexene derivatives is also described. The intermediacy of a carbon-centered radical results in the loss of the original stereochemistry of the parent alkyl halides, creating the potential for asymmetric cross-coupling of racemic alkyl halides.

遷移金属触媒を用いるハロゲン化アルキル類と有機金属試薬とのクロスカップリング反応

Cross-coupling reaction of organic halides with main group organometallic reagents has now become one of the most practical and reliable methods for constructing C-C bonds in organic synthesis. During the last three decades numbers of such reactions using organic halides bearing C (sp2) -X bond have been developed by the aid of transition-metal catalysts, especially Pd and Ni. On the other hand, the use of alkyl halides in transition-metal catalyzed cross-coupling reaction had not well been developed until quite recently. This is probably due to the low reactivities of alkyl halides toward oxidative addition and also to undesirable facile β-elimination from alkylmetal intermediates. Since several years ago, however, some significant methodological evolutions to overcome these difficulties have been achieved by tuning up the ligands and/or constructing novel catalytic systems based on new mechanisms. This review article summarizes recent progress in transition metal-catalyzed cross-coupling reaction of alkyl halides with organometallic reagents.