Organocatalytic cycloaddition-elimination cascade for atroposelective construction of heterobiaryls
Wen-Lei Xu1, Wei-Ming Zhao1, Ru-Xia Zhang1
1Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, College of Chemistry & Materials Science, Northwest University Xi'an 710102 P. R. China zhoul@nwu.edu.cn.
Abstract:
The first chiral phosphoric acid (CPA) catalyzed cycloaddition-elimination cascade reaction of 2-naphthol- and phenol-derived enecarbamates with azonaphthalenes has been established, providing a highly atroposelective route to an array of axially chiral aryl-C3-benzoindoles in excellent yields with excellent enantioselectivities. The success of this strategy derives from the stepwise process involving CPA-catalyzed asymmetric formal [3 + 2] cycloaddition and subsequent central-to-axial chirality conversion by elimination of a carbamate. In addition, the practicality of this reaction had been verified by varieties of transformations towards functionalized atropisomers.
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