| We have examined the possibility of an environmentally friendly process related to the synthesis of pyrrole derivatives reported by Derek H. R. Barton 4m, P but incorporating alternative reagents. A solvent study was also conducted in this synthetic scheme and resulted in interesting conclusions discussed later. Hence we report an improved and environmentally friendly synthesis of 3,4-dialkyl-lH-pyrrole-2-carboxylates.; We also report an efficient and essentially one-pot synthesis of pyrrole derivatives where ethylisocyanoacetate was reacted with potassium hydride to form the anion of ethyl isocyanoacetate and the resulting anion underwent a 1,3-dipolar cycloaddition with acetylene esters to give the Michael adduct followed by intramolecular cyclization and then isomerization to give the potassium salts of 3-substituted pyrrole-2,4-dicarboxylic acid diethyl esters followed by acid work-up to give 3-substituted-1H-pyrrole-2,4-dicarboxylic acid diethyl esters. (Abstract shortened by UMI.)... |
