Synthesis of chiral α-carbonyl-δ-nitro-ketenedithioacetals via l-proline-catalyzed Michael addition reaction

Regioselective synthesis of 1,1-bis(methylthio)-6-nitro-5-arylhex-1-en-3-one has been achieved from α-alkenoylketene dithioacetals with nitromethane using l-proline catalyst via Michael addition. The synthesized compounds 3a–j were well characterised by NMR and mass spectral techniques. One of the structures was confirmed by single crystal XRD. The enantioselectivity and its specific rotation of synthesized compounds were analyzed. All the compounds were screened for their anti-oxidant property, most of the compounds having the ability to scavenge free radicals.