Nitration of 4-methyl-5,6-dihydro-2H-pyran and some aspects of the preparation and isomerization of nitrodihydropyrans

The reaction of 4-methyl-5,6-dihydro-2H-pyran with acetyl nitrate to give additive and substitutive nitration products has been examined. It is shown that the addition product, 4-acetoxy-4-methyl-3-nitro-tetrahydropyran, is deacylated on treatment with bases to give an α,Β-unsaturated nitro-compound which isomerizes under the reaction conditions to a Β,γ-unsaturated nitro-compound. 4-Acetoxy-4-nitromethyltetrahydropyran behaves similarly.