Catalytic Bismuth(V)-Mediated Oxidation of Hydrazones into Diazo Compounds
Nour Tanbouza, Laurent Caron, Azadeh Khoshoei and Thierry Ollevier*
*Département de Chimie, Université Laval, 1045 avenue de la Médecine, Québec, Québec G1V 0A6, Canada, Email: thierry.ollevierchm.ulaval.ca
N. Tanbouza, L. Caron, A. Khoshoei, T. Ollevier, Org. Lett., 2022, 24, 2675-2678.
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A Bi(V) compound catalyzes an oxidation of hydrazones into diazo compounds in the presence NaBO3·H2O as the terminal oxidant. Ph3Bi(OAc)2 as catalyst is in situ generated from BiPh3 and AcOH. The reaction was applied for the synthesis of diazocarbonyls and 2,2,2-trifluoromethyl diazoalkanes in very good yields.
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To a vial equipped with a magnetic stir bar, Ph3Bi (5 mol %) and NaBO3·H2O (1.1 equiv) were suspended in MeOH (0.8 mL). The hydrazone (1 equiv) was then added, followed by AcOH (3 mL). The reaction was vigorously stirred at room temperature. The progress of the reaction was monitored by TLC. After completion, the reaction was quenched with H2O (3 mL) and extracted with Et2O (3 x 5 mL). The organic phase was dried over MgSO4 and concentrated under reduced pressure. The residue was purified by silica gel flash column chromatography (100:0 - 90:10 Hexanes/EtOAc) to afford the pure product. Proof of purity and identity was obtained by 1H, 13C, and 19F NMR spectroscopy.