A new synthesis of ‘push–pull’ naphthalenes by condensation of nitro-2-methylbenzoate esters with dimethylacetamide dimethyl acetal

Whereas condensation of 2-methyl-3-nitrobenzoate esters with dimethylformamide dimethyl acetal gives 5-nitroisocoumarin, analogous condensation with dimethylacetamide dimethyl acetal proceeds via a different route, affording 1-methoxy-3-dimethylamino-5-nitronaphthalene in good yield. Extension of the reaction to other naphthalenes with this novel ‘push–pull’ substitution motif has been explored. A deuterium labelling study revealed that equilibration of the alkoxy groups in the reaction mixture took place before the final carbocyclisation.