Department of Chemistry, The University of Kansas, 1140 Gray-Little Hall, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States.
J Org Chem. 2020 Dec 4;85(23):14827-14846. doi: 10.1021/acs.joc.0c01020. Epub 2020 Nov 5.
-(Aryloxy)imines, readily accessible by condensation/tautomerization of (pseudo)benzylic primary amines and 2,6-di--butyl-1,4-benzoquinone, undergo efficient allylation to afford a wide range of homoallylic primary amines following hydrolytic workup. Deprotonation of -(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 -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 -(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.
-（芳氧基）亚胺可通过（伪）苄基伯胺和 2,6-二叔丁基-1,4-苯醌的缩合/互变异构反应轻松获得，经水解后可有效地与烯丙基钯(II)亲电试剂进行加成反应，得到各种同烯丙基伯胺。-(芳氧基）亚胺的脱质子化生成一个离域的 2-氮杂烯丙基阴离子型亲核试剂，它与烯丙基碳酸酯生成的烯丙基钯(II)亲电试剂发生非芳构化 C-C 键形成反应。这种反应反转使（伪）苄基伯胺的形式α-烯丙基化成为可能。机理研究表明，所需键形成反应的表观区域选择性是一个收敛过程，由-(芳氧基）亚胺的非选择性烯丙基化引发，生成几种区域异构体，然后通过逐步[1,3]-或协同[3,3]-σ迁移重排，最终收敛得到所需胺产物的区域异构体。
