Functionalized Benzylic Magnesium Reagents through a Sulfur–Magnesium Exchange

Stoll, Armin H.; Krasovskiy, Arkady; Knöchel, Paul

doi:10.1002/anie.200501882

Cited by 68 publications

(15 citation statements)

References 33 publications

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“…Thus, benzylic magnesium reagents are incompatible with ester or nitrile groups, even at À78 8C. [25] The new procedure described above, using Mg in the presence of ZnCl 2 and LiCl, has been successfully used to prepare a range of functionalized benzylic zinc reagents of type 13 starting from the corresponding benzylic chlorides 14. The reaction proceeds via an intermediate benzylic magnesium compound 15, which is transmetalated in situ to 13.…”

Section: Resultsmentioning

confidence: 99%

Preparation of Polyfunctional Arylmagnesium, Arylzinc, and Benzylic Zinc Reagents by Using Magnesium in the Presence of LiCl

Piller

Metzger

Schade

et al. 2009

Chemistry A European J

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174

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The presence of LiCl considerably facilitates the insertion of magnesium into various aromatic and heterocyclic bromides. Several functional groups, such as -OBoc, -OTs, -Cl, -F, -CF(3), -OMe, -NMe(2), and -N(2)NR(2), are well tolerated. The presence of a cyano group leads in some cases to competitive reduction of the organic halide to the corresponding ArH compound. The presence of sensitive groups such as methyl or ethyl ester is tolerated upon in situ trapping of the intermediate magnesium reagent with ZnCl(2). This method can also be applied to the preparation of functionalized benzylic zinc reagents from benzylic chlorides. In the case of di- or tribromoaryl derivatives, directing groups such as -OPiv, -OTs, -N(2)NR(2), or -OAc orient the zinc insertion (Zn/LiCl) to the ortho-position, while the reaction with Mg/LiCl or Mg/LiCl/ZnCl(2) leads to regioselective insertion into the para-carbon-bromine bond. Large-scale experiments (20-100 mmol) for all of the metalation procedures are described.

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Section: Resultsmentioning

confidence: 99%

Preparation of Polyfunctional Arylmagnesium, Arylzinc, and Benzylic Zinc Reagents by Using Magnesium in the Presence of LiCl

Piller

Metzger

Schade

et al. 2009

Chemistry A European J

Self Cite

174

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“…1b ). For instance, organometallic reagents such as Grignard reagents 40 , 41 and organolithium compounds 42 can react with benzenesulfonothioates to produce unsymmetrical sulfides. However, organometallic reagents are air- and moisture-sensitive and the methods suffer from limited substrate scope and poor chemoselectivity.…”

Section: Introductionmentioning

confidence: 99%

Nickel-catalyzed reductive thiolation and selenylation of unactivated alkyl bromides

et al. 2018

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Chalcogen-containing compounds have received considerable attention because of their manifold applications in agrochemicals, pharmaceuticals, and material science. While many classical methods have been developed for preparing organic sulfides, most of them exploited the transition-metal-catalyzed cross-couplings of aryl halides or pseudo halides with thiols or disulfides, with harsh reaction conditions usually being required. Herein, we present a user-friendly, nickel-catalyzed reductive thiolation of unactivated primary and secondary alkyl bromides with thiosulfonates as reliable thiolation reagents, which are easily prepared and bench-stable. Furthermore, a series of selenides is also prepared in a similar fashion with selenosulfonates as selenolation reagents. This catalytic method offers a facile synthesis of a wide range of unsymmetrical alkyl-aryl or alkyl-alkyl sulfides and selenides under mild conditions with an excellent tolerance of functional groups. Likewise, the use of sensitive and stoichiometric organometallic reagents can be avoided.

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“…2 More recently, we have also reported the preparation of benzylic zinc reagents by the direct insertion of zinc dust into benzylic chlorides in the presence of lithium chloride. 3 These benzylic zinc reagents have in contrast to benzylic lithium or magnesium reagents 4 an excellent functional group tolerance, for example, esters, nitriles, or even sensitive ketones are well tolerated. Furthermore, reactions of these new benzylic zinc reagents with acid chlorides, aldehydes, enones, and allylic bromides provide polyfunctional products.…”

Section: Introductionmentioning

confidence: 99%

Large-Scale Preparation of Polyfunctional Benzylic Zinc Reagents by Direct Insertion of Zinc Dust into Benzylic Chlorides in the Presence of Lithium Chloride

Metzger¹,

Argyo²,

Knöchel³

2009

Synthesis

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Functionalized Benzylic Magnesium Reagents through a Sulfur–Magnesium Exchange

Abstract: Switch it: Iodobiphenyl thioethers readily undergo an iodine–magnesium exchange followed by, after the addition of tBuOLi, an intramolecular sulfur–magnesium exchange, which provides benzylic magnesium reagents in excellent yield through a fragmentation reaction.

Cited by 68 publications

References 33 publications

Preparation of Polyfunctional Arylmagnesium, Arylzinc, and Benzylic Zinc Reagents by Using Magnesium in the Presence of LiCl

Preparation of Polyfunctional Arylmagnesium, Arylzinc, and Benzylic Zinc Reagents by Using Magnesium in the Presence of LiCl

Nickel-catalyzed reductive thiolation and selenylation of unactivated alkyl bromides

Large-Scale Preparation of Polyfunctional Benzylic Zinc Reagents by Direct Insertion of Zinc Dust into Benzylic Chlorides in the Presence of Lithium Chloride

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