Synthesis of 2-methyl-3-nitropyridines, 2-styryl-3-nitropyridines and their reactions with S-nucleophiles

Nitroarenes and nitrohetarenes are valuable synthetic intermediates in organic synthesis due to variety of possible chemical transformations. One of the most important and flexible tools for nitroarenes functionalization is nucleophilic aromatic substitution (S_NAr). This reaction generally requires number of conjugated electron-withdrawing groups and S_NAr of non-activated nitro groups is rather uncommon. Most of these examples were obtained on polynitrobenzenes, but little is known about reactions of non-activated 3-nitropyridines.

Here we report synthesis of several 2-methyl-3-nitropyridines and their reactions with various aromatic aldehydes, leading to corresponding 2-styrylpyridines under mild conditions. Both 2-methyl- and 2-styryl-3-nitropyridines readily react with thiolate-anions and give substitution products in good yields. Chemo- and regioselectivity is discussed, some of 2-styrylpyridines also showed remarkable fluorescent properties.