Green and Efficient Construction of Chromeno[3,4- c ]pyrrole Core via Barton-Zard Reaction from 3-Nitro-2 H -chromenes and Ethyl Isocyanoacetate.

A regioselective one-pot method for the synthesis of 1-ethyl 2,4-dihydrochromene[3,4- c ]pyrroles in 63-94% yields from available 2-phenyl-, 2-trifluoro(trichloro)methyl- or 2-phenyl-2-(trifluoromethyl)-3-nitro-2 H -chromenes and ethyl isocyanoacetate through the Barton-Zard reaction in ethanol at reflux for 0.5 h, using K 2 CO 3 as a base, has been developed.