Nitroalkanes react with dimethyl maleate giving a tandem Michael addition/elimination
of nitrous acid. The obtained (E)-2-alkylidene dimethyl succinates are: (i) reduced to the corresponding 2-alkyl dimethyl
succinates which after hydrolysis produce 1,4-dicarboxylic acids that are prone to
convert into the corresponding 3-alkyl succinic anhydrides or (ii) hydrolysed to (E)-2-alkylidene-succinic acids that are easily cyclised to (E)-3-alkylidene succinic anhydrides.
nitroalkanes - 3-alkyl succinic anhydrides - 3-alkylidene succinic anhydrides - dimethyl
maleate - heterocyclic compounds