One-Pot Synthesis of 3,4-Disubstituted Pyrrole-2-Esters

Significance

As perhaps not uncommonly observed but rarely reported, an original procedure proceeds through several generations of improvement. In the reported case, it is also a progression in a generation of chemists. The method for the synthesis of 3,4-disubstituted pyrrole-2-esters, originally disclosed by Barton and Zard over 15 years ago (D. H. R. Barton, J. Kervagore, S. Zard Tetrahedron 1990, 21, 7587-7598), is now reported in an improved version. Under the new conditions, the reaction of β-acetoxy nitro derivatives and acetylenic esters with ethyl isocyanoacetate under acylative, base-mediated conditions leads to substituted pyrrolo carboxylates in good to excellent yields in a single pot.