Chemistry of nitro groups and nitro compounds has long been intensively studied. Despite their long history, new reactions and methodologies are still being found today. This is due to the diverse reactivity of the nitro group. The importance of nitro chemistry will continue to increase in the future in terms of elaborate synthesis. In this article, we will take a walk through the recent advances in nitro chemistry that have been made in past decades.

A synthetic method for fully alkylated/arylated nicotinates was achieved by FeCl ₃ -mediated condensation of enamino esters and enones.

A carbamoyl-substituted nitrile oxide was generated upon treatment of easily available 2-methyl-4-nitro-3-isoxazolin-5(2H)-one with THF (not dried); the reaction proceeded efficiently even in the absence of any special reagents and reaction conditions. The nitrile oxide caused 1,3-dipolar cycloaddition with common aliphatic nitriles or electron-rich aromatic nitriles to afford 3-functionalized 1,2,4-oxadiazoles, which are expected to serve as precursors for the preparation of a variety of functional materials by the chemical transformation of the carbamoyl group. While conventional preparative methods for 1,2,4-oxadiazoles involve the cycloaddition of an electron-rich nitrile oxide with an electron-deficient nitrile or a nitrile activated by a Lewis acid, our method employs the complementary combination of an electron-rich nitrile and an electron-deficient nitrile oxide- the inverse electron-demand 1,3-cycloaddition. The DFT calculations using B3LYP 6-31G* supported the abovementioned inverse reactivity, and also suggested the presence of an accelerating effect by the carbamoyl group as a result of hydrogen bond formation with a dipolarophilic nitrile.

Reactions of two isomeric nitropyrimidinones with bidentate enolate anions were studied. When 3-methyl-5-nitropyrimidin-4(3H)-one (1) was employed, ring transformation proceeded to give pyridin-4(1H)-ones 3 functionalized at the 3- or 5-positions. This pyrimidin-4-one 1 behaved as an activated diformylamine HN(CHO)₂. 1-Methyl-5-nitropyrimidin-2(1H)-one (2) afforded polyfunctionalized bicyclo[3.3.1]nonene derivatives 7 and 8 and/or p-nitrophenol derivatives 9. In this case, pyrimidin-2-one 2 acted as the synthetic equivalent of unstable O₂NCH(CHO)₂. These two nitropyrimidinones are valuable intermediates for the synthesis of polyfunctionalized compounds.