Übergangsmetall‐katalysierte Additionsreaktionen von 3‐Phenyl‐2H‐azirinen und Acetylencarbonsäureestern

Transition Metal Catalyzed Addition Reactions of 3‐Phenyl‐2 H ‐azirines and Alkyl Acetylene Carboxylates In the presence of molybdenum hexacarbonyl, the 3‐phenyl‐2 H ‐azirines 1 and 7 react with alkyl acetylene carboxylates 2 via the cleavage of the C, N‐double bond to give 2 H ‐pyrroles 5 or pyrrole 9 (Table) , whose structures were deduced from the spectra data, in particular 13 C‐NMR. data. The 2 H ‐pyrrole 5a was also obtained by treatment of a mixture of 1 and 2a with tungsten hexachloride. A tentative mechanism for the formation of the 2 H ‐pyrroles is formulated.