Synthesis of 2-Nitrocyclopentanone

The synthetic utility of cyclic α-nitroketones as well as the preparation of these useful synthetic intermediates has recently been reviewed1. Although the dipotassium salt of 2,5-dinitrocyclopentanone has been synthesized2, 2-nitrocyclopentanone itself could not be prepared by nitrating cyclopentanone with an alkyl nitrate and either potassium amide in liquid ammonia2 or potassium t-butoxide in tetrahydrofuran3. Furthermore, the reaction of 1-bromocyclopentene with dinitrogen tetroxide led only to a 15–20% yield of 2-nitrocyclopentanone as the 2,4-dinitrophenylhydrazone derivative4. The lone report of an actual preparation of 2-nitrocyclopentanone appears in a patent however with no characterization of the compound5. We now wish to report the synthesis and characterization of 2-nitrocyclopentanone, a potential versatile synthetic intermediate. Starting with cyclopentanone we have achieved the synthesis of the title compound by three methods outlined in Scheme I.