Qi Z, Wen S, Liu Z, Jiang D. Oxygen-Promoted 6-
endo-trig Cyclization of β,γ-Unsaturated Hydrazones/Ketoximes with Diazonium Tetrafluoroborates for Pyridazin-4(1
H)-ones/Oxazin-4(1
H)-ones.
Org Lett 2023;
25:6110-6115. [PMID:
37581359 DOI:
10.1021/acs.orglett.3c02073]
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Abstract
An oxidative 6-endo-trig cyclization and [2 + 2] cycloaddition of β,γ-unsaturated hydrazones/ketoximes and diazonium tetrafluoroborates for a synthetic strategy to pyridazin-4(1H)-ones/oxazin-4(1H)-ones under metal-free conditions is presented in a one-pot procedure. This protocol features excellent functional group tolerance and remarkable regioselectivity. A mechanistic study has been verified via 18O labeling and the H218O labeling method, in which O2 acts as both a reaction component and an oxidant.
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