Carbon Dioxide: A Reagent for the Simultaneous Protection of Nucleophilic Centers and the Activation of Alternative Locations to Electrophilic Attack. 17. Substitution of N-Methyl-1- and N-Methyl-2-naphthylamine and Side-Chain Functionalization of o-Toluidine

Article abstract of DOI:10.1021/jo00017a012

N-Methyl-1-naphthylamine is readily converted into a range of 2-substituted derivatives in one-pot sequences, using carbon dioxide for NH protection.Similarly, N-methyl-2-naphthylamine yields 3-substituted derivatives in the first direct preparation of 2,3-disubstituted naphthalenes.The intermediate lithium carbamates are further lithiated by tert-butyllithium at the 2-position for N-methyl-1-naphthylamine and at the 3-position for N-methyl-2-naphthylamine and then reacted with an electrophile; the products undergo acid-catalyzed decarboxylation during workup. o-Toluidine is converted into its methyl-functionalized derivatives in a similar way, except that 2 equiv of tert-butyllithium are used for the further lithiation of the intermediate lithium carbamate.