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Formal α‑Allylation of Primary Amines by a Dearomative, Palladium-Catalyzed Umpolung Allylation of N‑(Aryloxy)imines

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journal contribution
posted on 06.11.2020, 00:57 by Luis M. Mori-Quiroz, Shrikant S. Londhe, Michael D. Clift
N-(Aryloxy)­imines, readily accessible by condensation/tautomerization of (pseudo)­benzylic primary amines and 2,6-di-tert-butyl-1,4-benzoquinone, undergo efficient allylation to afford a wide range of homoallylic primary amines following hydrolytic workup. Deprotonation of N-(aryloxy)­imines generates a delocalized 2-azaallyl anion-type nucleophile that engages in dearomative C–C bond-forming reactions with allylpalladium­(II) electrophiles generated from allylic tert-butyl carbonates. This reactivity umpolung enables the formal α-allylation of (pseudo)­benzylic primary amines. Mechanistic studies reveal that the apparent regioselectivity of the desired bond-forming event is a convergent process that is initiated by unselective allylation of N-(aryloxy)­imines to give several regioisomeric species, which subsequently rearrange via stepwise [1,3]- or concerted [3,3]-sigmatropic shifts, ultimately converging to provide the desired regioisomer of the amine products.