Versatile Synthesis of Pyrrole-2-acetic Esters and (Pyridine-2-one)-3-acetic Amides by Palladium-Catalyzed, Carbon Dioxide-Promoted Oxidative Carbonylation of (Z)-(2-En-4-ynyl)amines
The oxidative carbonylation of readily available (Z)-(2-en-4-ynyl)amines, catalyzed by the PdI2-KI system, selectively afforded in satisfactory yields (40–95 %) either pyrrole-2-acetic ester or (pyridine-2-one)-3-acetic amide derivatives, depending on the susbtitution pattern of the substrate and the reaction conditions. The presence of an excess of carbon dioxide proved in most cases to be beneficial
A general and regioselective synthesis of substituted pyrroles 2 by cycloisomerization of readily available (Z)-(2-en-4-ynyl)amines 1 is reported. Spontaneous cycloisomerization leading to 2 occurred in the course of preparation of enynamines bearing a terminal triple bond or a triple bond substituted with a phenyl or a CH2OTHP group. When the triple bond was substituted with an alkyl or alkenyl group