Carboxyzincation employing carbon dioxide and zinc powder: Cobalt-catalyzed multicomponent coupling reactions with alkynes

Article abstract of DOI:10.1021/jacs.6b02961

Cobalt-catalyzed carboxyzincation reactions employing carbon dioxide and zinc metal powder are developed. By using alkynes as substrates, regio- and stereodefined (Z)-β-zincated acrylates are provided. The corresponding alkenylzinc moiety can be converted to various substituents, affording multisubstituted acrylic acids. Furthermore, by adding electron-deficient alkene to the reaction system, the four-component coupling reactions of alkyne, alkene, CO₂, and the Zn atom proceed via carboxyzincation.

Full text of DOI:10.1021/jacs.6b02961

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Communication
Carboxyzincation Employing Carbon Dioxide and Zinc Powder:
Cobalt-Catalyzed Multicomponent Coupling Reactions with Alkynes
Keisuke Nogi, Tetsuaki Fujihara, Jun Terao, and Yasushi Tsuji
J. Am. Chem. Soc., Just Accepted Manuscript • DOI: 10.1021/jacs.6b02961 • Publication Date (Web): 18 Apr 2016
Downloaded from http://pubs.acs.org on April 18, 2016
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aReaction conditions; alkyne (1a, 0.25 mmol), CoI2(dppf) (10 mol%), Zn
powder (1.5 equiv), Zn(OAc)2 (10 mol %), Et4NI (10 mol %), under CO2 (1
atm) in CH3CN/DMF (0.55 mL, v/v = 10/1) at 40 °C for 20 h. bDetermined
by 1H NMR analysis. cIsolated yield.
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aReaction conditions; alkyne (1), CoI2(dppf) (10 mol %), Zn powder (1.5 equiv),
Zn(OAc)2 (10 mol %), Et4NI (10 mol %), under CO2 (1 atm) in CH3CN/DMF (v/v =
10/1) at 40 °C for 20 h. bIsolated yield. cCoBr2(dppf) (10 mol%) as a catalyst. dThe
corresponding halide (1.2 equiv or 1.5 equiv), Pd(PPh3)4 (2.0 mol %) at 70 °C for 20 h.
eAn allyl bromide (2.0 equiv), CuCN·2LiCl (20 mol%), –20 °C to RT for 20 h.
fCH3CN/DMF (v/v = 1/4). gAt 25 °C. hCH3CN/DMF (v/v = 1/1), at 50 °C.iAn aryl
iodide (1.5 equiv), PdCl2(PPh3)2 (2.0 mol %) at 70 °C for 20 h. jBy 1H NMR.
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aReaction conditions; alkyne (1, 0.30 mmol), electron-deficient alkene (3,
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0.25 mmol) CoI2(dppf) (10 mol%), Zn powder (1.5 equiv), Zn(OAc)2 (20
mol %), Bu4NI (20 mol %), under CO2 (1 atm) in CH3CN (0.50 mL) at
25 °C for 20 h. b1j: Ar–CC–Ar, Ar=4-ClC6H4; 1k: Ar–CC–Ar,
Ar=3-CF3C6H4; 1l: MeOOC–CC–C5H11. c3a: butyl acrylate; 3b: methyl
acrylate; 3c: ethyl acrylate; 3d: tert-butyl acrylate; 3e: dimethyl acryla-
mide. dIsolated yield.
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: MeOOC–CC–
C5H11
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