Electrosynthesis of Stabilized Diazo Compounds from Hydrazones

Nour Tanbouza, Alessia Petti, Matthew C. Leech, Laurent Caron, Jamie M. Walsh, Kevin Lam* and Thierry Ollevier*

*University of Greenwich, Chatham Maritime, Chatham, Kent ME4 4TB, U.K.; Université Laval, Québec, QC G1V 0A6, Canada, Email: K.Lamgreenwich.ac.uk, thierry.ollevierchm.ulaval.ca

N. Tanbouza, A. Petti, M. C. Leech, L. Caron, J. M. Walsh, K. Lam, T. Ollevier, Org. Lett., 2022, 24, 4665-4663.

DOI: 10.1021/acs.orglett.2c01803

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Abstract

An electrochemical synthesis provides diazo compounds from hydrazones in very high yields and avoids the use of harsh and toxic chemical oxidants. This reaction is practically simple to set up, offers mild conditions, and is highly electron efficient (3 F/mol).

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proposed mechanism

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General procedure for the electrosynthesis of stabilized diazo compounds

In a 5 mL ElectraSyn 2.0 vial, the hydrazone (0.4 mmol, 1 equiv), KI (0.2 mmol, 33 mg, 0.5 equiv), and NH₄OAc (2 mmol, 154 mg, 5 equiv) were dissolved in CH₃CN (5 mL). The ElectraSyn 2.0 cap was equipped with a C_gr anode (working electrode) and a Ni cathode (counter electrode). The reaction conditions were set to 50 mA and 3 F/mol. The reaction was stirred vigorously at rt. The mixture was quenched with freshly prepared sat. aq. Na₂S₂O₈, extracted with Et₂O and brine, and dried over MgSO₄. If necessary, the crude product was purified by flash chromatography (Hexanes/EtOAc).

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Key Words

Diazo Compounds, Electrochemistry

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ID: J54-Y2022