Transition from π Radicals to σ Radicals: Substituent‐Tuned Cyclization of Hydrazonyl Radicals |
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| Authors: | Xiu‐Long Yang Prof Dr Wei Yu Prof Dr Bing Han |
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| Institution: | State Key Laboratory of Applied Organic Chemistry and College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000 (P. R. China) |
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| Abstract: | Hydrazonyl radicals are known for their π‐electronic structures; however, their σ‐electronic structures have not been reported as yet. Herein, we show that readily accessible β,γ‐ and γ,δ‐unsaturated N‐trichloroacetyl and N‐trifluoroacetyl hydrazones can be conveniently converted into hydrazonyl σ radicals, which subsequently undergo 5‐exo‐trig radical cyclization at the N1 or N2 atom to form pyrazolines and azomethine imines, respectively. |
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| Keywords: | alkenes cyclization heterocycles radicals synthetic methods |
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