Copper-Catalyzed Umpolung Reactivity of Propargylic Carbonates in the Presence of Diboronates: One Stone Four Birds
Wennan Dong, Zhifei Zhao, Cheng-Zhi Gu*, Jing-Gong Liu, Shuang Yang, Xinqiang Fang*
*School of Chemistry and Chemical Engineering, Shihezi University, Shihezi 832000; University of Chinese Academy of Sciences, Fuzhou 350100, China,
Email: gcz_tea
shzu.edu.cn, xqfangfjirsm.ac.cn
W. Dong, Z. Zhao, C.-Z. Gu, J.-G. Liu, S. Yang, X. Fang, J. Am. Chem. Soc., 2023, 145, 27539-27554.
DOI: 10.1021/jacs.3c09155
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Abstract
Copper catalysis and B2pin2-mediated Umpolung reactivity of propargylic carbonates realize both allylation and propargylation of aldehydes and ketones without additional reductants. Three types of allylation products and one type of propargylation product are generated efficiently, and all allylation products are formed with syn-configurations predominantly.
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Typical procedure for the synthesis of compound 3a
In an N2-filled glove-box, to a solution of CuOAc (4.8 mg, 0.04 mmol, 20 mol%) and ligand L22 (36 mg, 0.048 mmol, 24 mol%) in THF (1 mL), was added NaOtBu (20 mg, 0.2 mmol, 1 equiv), and the reaction was stirred for 1 h at 30 °C. B2pin2 (250 mg, 1 mmol, 5 equiv) was then added and the color of the solution immediately turned to dark brown. After 30 min, a solution of propargyl alcohol ester (1a) (47 mg, 0.2 mmol, 1 equiv), PhCHO (2a) (32 mg, 0.3 mmol, 1.5 equiv) and H2O (3.6 mg, 0.2 mmol, 1 equiv) in THF (1 mL) was then added dropwise at 30 °C. After 4 h, the solution was quenched by passing through a short plug of celite and silica gel and washed with THF (3 x 2 mL). The filtrate was allowed to cool to at 0 °C (ice bath) and H2O2 (1 mL) and 2 N NaOH (0.500 mL, 1.00 mmol) were added. The resulting solution was allowed to stir for 1 h. The mixture was diluted with water (3 mL), washed with EtOAc (3 x 10 mL) and filtered through a plug of Na2SO4 and silica gel. The filtrate was concentrated in vacuo to provide yellow oil, which was purified by silica gel chromatography (petroleum ether/ethyl acetate, v:v = 7:1) to afford β-hydroxyketone 3a as colorless oil (44.5 mg, 83% yield, >20:1 dr).
Key Words
ID: J48-Y2023
