Recent advances in the chemistry of 3-nitro-2H- and 3-nitro-4H-chromenes

The review integrates and systematically describes data on the methods of synthesis, reactivity and biological activity of 3-nitro-2H-chromenes published over the last five years and data on 3-nitro-4H-chromenes and related 3-nitro-4H-pyrans published over the whole investigation period. Nucleophilic addition, including asymmetric synthesis, cycloaddition and redox reactions involving the C=C double bond and the nitro group of 3-nitro-2H-chromenes, are considered. The transformations of new and poorly investigated 3-nitro-4H-chromenes include reactions of 4-sulfanyl-substituted 3-nitro-4H-chromenes with nucleophiles, reactions of the nitroenamine moiety and removal of the alkylsulfanyl group using reductive processes. Reaction mechanisms and stereochemistry of the reaction products are discussed. The bibliography includes 103 references.