Initially, the domino annulation reaction of cinnamil 1a and malonodinitrile 2a were selected as the model substrates to optimize the reaction conditions (Table ). With 10 mol% stable N-heterocyclic carbene (IPr, 1,3-bis(2,6-diisopropyl phenyl)-imidazole-2-ylidene) as a Brønsted base, the domino reaction proceeded smoothly in THF at room temperature to afford the desired product 3a in 77% yield and >20:1 d.r. within 10 min ). Encouraged by this result, several other common organic bases, such as triethylamine, DBU, DABCO and DACH were examined for the reaction (Table , entries 2-5). All these bases can catalyze the domino annulation reaction to give the desired product in high yields. The strong inorganic base sodium hydroxide was also tested for the reaction, but only gave 3a in low yield (Table ). Carbonate salts Na 2 CO 3 and Cs 2 CO 3 catalyzed the reaction in good yields (Table and). K 2 CO 3 catalyzed the domino reaction to produce the desired product in the 96% yield (Table , entry 9). K 3 PO 4 can also catalyze the reaction to afford 3a in 92% yield (Table , entry 10). A brief screening of the reaction media showed that methanol was the best choice in terms of reaction yield (Table , entries 11-15). Lowering the base loading to 10 mol% resulted in decreased reaction yield (Table ). Finally, control experiment showed that in the absence of a base, no desired product was produced (Table . Under the optimized reaction conditions, the generality and limitations of this method was then evaluated by reacting of various cinnamils and malonodinitrile. As shown in Scheme 2, both electrondonating and electron-withdrawing groups substituted cinnamils participated in the domino annulation reaction smoothly to furnish the corresponding products in good to excellent yields (3b-3j). The steric effect was observed by checking of substrates with methyl group at different positions on the phenyl rings (3b-3d). 2-Naphthyl substituted cinnamil performed the reaction to give 3k in 57% yield. We attributed this reduced yield to the steric effect of the bulky naphthyl groups. Substrates containing heteroaryl substituents such as 2-furyl and 2-thienyl were well tolerated, delivering the corresponding products 3l and 3m in high yields.