Chemo-, Regio-, and Stereoselective Construction of Core Skeleton of Furo[2,3-b]pyrrole via Multicomponent Bicyclization Reaction.

An efficient and straightforward N-ethyldiisopropylamine (DIPEA)-catalyzed multicomponent bicyclization reaction was developed to synthesize furo[2,3-b]pyrrole derivatives from ß-ketothioamides, glyoxals, and ethyl cyanacetate in EtOH at rt for 1.5 h. This was achieved via a sequential Knoevenagel condensation, Michael addition, and double cyclization, resulting in continuous formation of four chemical bonds (two C-C, two C-O, and one C-N bonds), two five-membered cycles, and three stereogenic centers in a one-pot operation.

Direct Construction of 2-Aryliminochromenes from Arynes, N,S-Keteneacetals, and DMF.

A concise and direct synthetic strategy for the construction of 2-aryliminochromene skeleton by cascade three-component coupling reaction of arynes, N,S-keteneacetals, and DMF in good yields has been disclosed. The process demonstrates the first example of aryne chemistry combined with N,S-keteneacetals. Using this strategy, an expeditious synthesis of biologically important arylimino-2H-chromene-3- carboxamides was achieved.