Facile Synthesis of β-Tribromomethyl and Dibromomethylenated Nitroalkanes via Conjugate Addition of Bromoform to Nitroalkenes

Addition of bromoform to conjugated nitroalkenes in the presence of Mg provided β-tribromomethyl nitroalkanes in good to excellent yields and diastereoselectivity. These novel Michael adducts, formed under radical conditions, underwent elimination of HBr in the same pot under reflux to afford β-dibromomethylenated nitroalkanes in good yield. Alternatively, a one-pot high yielding synthesis of the dibromides was possible under anionic conditions via LDA mediated addition of bromoform to nitroalkenes.