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Organocatalytic Aryl–Aryl Bond Formation: An Atroposelective [3,3]-Rearrangement Approach to BINAM Derivatives

2013; American Chemical Society; Volume: 135; Issue: 20 Linguagem: Inglês

10.1021/ja401709k

1943-2984

Gongqiang Li, Hongyin Gao, Craig Keene, Michael Devonas, Daniel H. Ess, László Kürti,

Chemical synthesis and alkaloids

Herein we disclose an organocatalytic aryl–aryl bond-forming process for the regio- and atroposelective synthesis of 2,2′-diamino-1,1′-binaphthalenes (BINAMs). In the presence of catalytic amounts of axially chiral phosphoric acids, achiral N,N′-binaphthyl hydrazines undergo a facile [3,3]-sigmatropic rearrangement to afford enantiomerically enriched BINAM derivatives in good to excellent yield. This transformation represents the first example of a metal-free, catalytic C(sp2)–C(sp2) bond formation between two aromatic rings with concomitant de novo atroposelective installation of an axis of chirality. Density functional calculations reveal that, in the transition state for C–C bond formation, the phosphoric acid proton of the catalyst is fully transferred to one of the N-atoms of the substrate, and the resulting phosphate acts as a chiral counterion.