Diastereoselective Isomerization of (E)-β-Nitroenones into β-Nitro-β,γ-Unsaturated Ketones under Microwave Conditions

We report herein an unprecedented conversion of β-nitroenones into β-nitro-β,γ-unsaturated ketones. The reaction proceeds under microwave irradiation, furnishing products in good yields and excellent diastereoselectivity. The mechanism of the reaction has been rationalized by means of DFT modelling, which showed that sequential enolization/isomerization steps allowed to break the conjugation of the reagent. The E isomer is preferentially formed thanks to the solvent, which acts catalytically and dictates the regiochemical outcome. Moreover, the obtained β-nitro-β,γ-unsaturated ketones have been efficiently converted into 1,2,5-trisubstituted pyrroles by a one-pot approach. (Figure presented.).