A direct preparation of N-unsubstituted pyrrole-2,5-dicarboxylates from 2-azidocarboxylic esters.
A new and easy method for synthesis of symmetric pyrrole-2,5-dicarboxylate derivatives via a simple titanium(IV)-mediated oxidative dimerization of 2-azidocarboxylic esters is described. The process involves a transformation of titanium(IV) enolates into nonisolated 2-iminoesters, which undergo an oxidative coupling and ring closure to give the aromatic pyrrole system. A mechanism, scope and limitations of the new method are discussed.
Ciez
Dariusz
D
Faculty of Chemistry, Jagiellonian University, 30-060 Kraków, Poland. ciez@chemia.uj.edu.pl
D001386:Azides / Q000737:chemistry*; D004952:Esters / Q000737:chemistry*; D015394:Molecular Structure; D010084:Oxidation-Reduction; D011758:Pyrroles / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism; D014025:Titanium / Q000737:chemistry
D001386:Azides; D004952:Esters; D011758:Pyrroles; D014025:Titanium