Boron Trifluoride-Promoted Indium(III) Triflate-Catalyzed Sequential One-Pot Synthesis of (1,2-Diaryl-2-oxoethyl)malonates from trans-2-Aryl-3-nitrocyclopropane-1,1-dicarboxylates and Activated Arenes

A sequential one-pot synthesis of Michael adducts of aroylmethylidenemalonates with activated aromatics is described. The method involves treatment of trans-2-aryl-3-nitro-cyclopropane-1,1-dicarboxylates with boron trifluoride etherate to form aroylmethylidenemalonates in situ and then addition of activated aromatics such as indoles, carbazole, pyrrole, thiophenes, methoxybenzenes and benzodioxole followed by a catalytic amount of indium(III) triflate to the same reaction vessel. To prove the synthetic potential of the resulting Michael adducts, one of the adducts was transformed into a pharmaceutically interesting dihydropyridazinone derivative.