Copper‐Catalyzed Selective Cross‐Couplings of Propargylic Ethers with Aryl Grignard Reagents

Jiang, Yifan; Ma, Yangyang; Ma, Enlu; Li, Zhiping

doi:10.1002/ajoc.201900409

Cited by 7 publications

(4 citation statements)

References 28 publications

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“…In contrast to the asymmetric synthesis, α‐substitution reactions of enantiomerically enriched propargylic alcohol derivatives have been reported. Substrates/reagent systems published to date are ammonium salt/ArMgBr/Cu cat., [7] salicylate/ArMgCl/Cu cat., [8] ester/cuprate, [9] bromide/heteroaryl cuprate, [10] and sulfonate/TMSCF 3 /Cu cat./KF [11] . In addition, indirect methods to access α‐substituted acetylenes have been published [12] .…”

Section: Introductionmentioning

confidence: 99%

α‐ and γ‐Regiocontrol and Enantiospecificity in the Copper‐Catalyzed Substitution Reaction of Propargylic Phosphates with Grignard Reagents

Kobayashi

Takashima

Motoyama

et al. 2021

Chemistry A European J

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The regioselectivity (r.s.) and enantiospecificity (e.s.) of the substitution reactions of secondary propargylic alcohol derivatives using reagents derived from ArMgBr and Cu salts were studied. First, the picolinate, 3‐methylpicolinate, and diethylphosphonate derivatives of Ph(CH2)2CH(OH)C≡CTMS were reacted with PhMgBr/CuCN in ratios of 2.5:2.7–2.5:0.25. The use of 2.5:0.25 ratio in THF/DME (6:1) at 0 °C for 1 h afforded the α‐substitution product from the phosphate with ≥98 % r.s. and 99 % e.s. CuBr⋅Me2S gave similar selectivity. The reaction system was then applied to phosphates derived from R1CH(OH)C≡CR2 and ArMgBr to obtain synthetically sufficient r.s. and e.s. values with R2=TMS, Ph, whereas iPr was borderline in terms of size as an R1 substituent. The presence of a substituent at the o‐position of Ar marginally affected the selectivity. We also found that the use of PhMgBr/Cu(acac)2 in a 2:1 ratio in THF produced the γ‐substitution products (allenes) with high r.s. and e.s.

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Section: Introductionmentioning

confidence: 99%

α‐ and γ‐Regiocontrol and Enantiospecificity in the Copper‐Catalyzed Substitution Reaction of Propargylic Phosphates with Grignard Reagents

Kobayashi

Takashima

Motoyama

et al. 2021

Chemistry A European J

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“…Li and co‐workers reported the copper‐catalyzed substrate‐directed cross‐coupling reaction of internal alkyne‐containing propargylic ethers with aryl Grignard reagents (Scheme 12). [23] In this study, the authors showed a single example for the stereospecific variants of the transformation. The reaction of the enantioenriched propargylic ether (97% ee) with phenylmagnesium chloride proceeded in the presence of copper bromide (5 mol%) to give the desired arylation product in 68% yield with 98% ee.…”

Section: Asymmetric Propargylic Substitution Of Propargylic Alcohol D...mentioning

confidence: 88%

Transition‐Metal‐Catalyzed Propargylic Substitution of Propargylic Alcohol Derivatives Bearing an Internal Alkyne Group

Tsuji

Kawatsura

2020

Asian J Org Chem

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The development of the transition-metal-catalyzed propargylic substitution of propargylic alcohol derivatives is one of the active research subjects in organic synthesis. In this minireview, we summarize the catalytic propargylic substitution of propargylic alcohol derivatives bearing an internal alkyne group using a transition metal as the catalyst. Although the asymmetric propargylic substitution of the substrate class still underdeveloped, some transition metal catalyses using nickel, palladium, and copper, and the cooperative catalysis enabled the challenging transformation. A various types of transition-metal catalysts are known to promote the non-asymmetric propargylic substitution of the internal alkyne-substituted propargylic alcohol derivatives via a propargylic cation intermediate, realizing the carboncarbon and carbon-heteroatom bond formation at the propargylic position.

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“…[15], salicylate/ArMgCl/Cu cat. [16], bromide/heteroaryl cuprate [17], and sulfonate/TMSCF 3 /Cu cat./KF [18]. The α-substitution using racemic substrates was reported as well [19][20][21][22].…”

Section: Introductionmentioning

confidence: 89%

Substitution of Secondary Propargylic Phosphates Using Aryl-Lithium-Based Copper Reagents

et al. 2023

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The substitution of secondary propargylic phosphates ROP(O)(OEt)2 where R = [Ph(CH2)2]C(H)(C≡CTMS)] Ph(CH2)2CH(OP(O)(OEt)2)(C≡CTMS) with copper reagents derived from PhLi and copper salts such as CuCl, CuCN, and Cu(acac)2 was studied to establish an ArLi-based reagent system. Among the reagents prepared, PhLi/CuCl (2:1) showed 98% α regioselectivity (rs), while PhLi/Cu(acac)2 was γ selective (>99% rs). PhLi prepared in situ from PhI and PhBr by Li-halogen exchange with t-BuLi was also used for the α selective substitution. A study using the (S)-phosphate disclosed 99% enantiospecificity (es) and the inversion of the stereochemistry. The substitution of five phosphates with substituted aryl reagents produced the corresponding propargylic products with high rs and es values. Similar reactivity and selectivity were observed with 2-furyl and 2-thienyl reagents, which were prepared via direct lithiation with n-BuLi.

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Copper‐Catalyzed Selective Cross‐Couplings of Propargylic Ethers with Aryl Grignard Reagents

Cited by 7 publications

References 28 publications

α‐ and γ‐Regiocontrol and Enantiospecificity in the Copper‐Catalyzed Substitution Reaction of Propargylic Phosphates with Grignard Reagents

α‐ and γ‐Regiocontrol and Enantiospecificity in the Copper‐Catalyzed Substitution Reaction of Propargylic Phosphates with Grignard Reagents

Transition‐Metal‐Catalyzed Propargylic Substitution of Propargylic Alcohol Derivatives Bearing an Internal Alkyne Group

Substitution of Secondary Propargylic Phosphates Using Aryl-Lithium-Based Copper Reagents

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