Transformations of Alkyl 2-(2,2-Disubstituted-ethenyl)amino-3-dimethylaminoprop-2-enoates: Synthesis of Alkyl 3,4-Disubstituted- and Alkyl 1-Acyl-3,4-disubstituted Pyrrole-2-carboxylates - Selič, Lovro; Stanovnik, Branko (Synthesis, 1999)