Nucleophilic aromatic substitution on 1-alkoxy-2-nitronaphthalene by 1-naphthyl Grignard reagents for the synthesis of 2-nitro-1,1′-binaphthyls

Treatment of 1-methoxy-2-nitronaphthalene with 1-naphthyl- and 2-methoxy-1-naphthylmagnesium bromide in diethyl ether–benzene at room temperature provides a facile entry to the corresponding 2-nitro-1,1′-binaphthyls in high yields. Induction of axial chirality into the binaphthyl bond has been achieved by using 1-menthoxy-2-nitronaphthalene as the substrate, giving 2-methoxy-2′-nitro-1,1′-binaphthyl of 78% ee. Also reported is the optical resolution of 2-amino-1,1′-binaphthyls, which can be easily prepared by reduction of the 2-nitro-1,1′-binaphthyls, by preparative LC on a cellulose-derived chiral stationary phase, or on silica gel after conversion into the diastereomeric menthyl carbamates.