Cyclodimerization of ?.?-cyanoacetylenes, catalyzed by low-valence cobalt complexes

Synthesis of Annelated Substituted Bipyridines and Terpyridines by Cobalt(I)-Catalyzed [2 + 2 + 2] Cycloaddition

“…This result contrasts with the ready transformation of 1 into 2-(3-cyanopropyl)- and 3-(3-cyanopropyl)cyclopenta[ b ]pyridines …”

“… a See Experimental Section. Regardless of the method used, 3−9% yields of 2-(3-cyanopropyl)- and/or 3-(3-cyanopropyl)cyclopenta[ b ]pyridines were also obtained …”