Transannular Reactions of Two Non‐Parallel 1,3‐Butadiyne Units − Syntheses, Structures and Protonation Reactions of 1‐Isopropyl‐1‐azacyclopentadeca‐3,5,11,13‐tetrayne and 1‐Isopropyl‐1‐azacyclohexadeca‐3,5,12,14‐tetrayne

The syntheses of 1‐isopropyl‐1‐azacyclopentadeca‐3,5,11,13‐tetrayne ( 15a ) and 1‐isopropyl‐1‐azacyclohexadeca‐3,5,12,14‐tetrayne ( 15b ) were accomplished in a stepwise approach. The key intermediates were 1,14‐dibromotetradeca‐2,4,10,12‐tetrayne ( 14a ) and 1,15‐dibromopentadeca‐2,4,11,13‐tetrayne ( 14b ). The ring closure to 15a and 15b was achieved by reaction with isopropylamine. X‐ray investigations on single crystals of 15a and 15b revealed a non‐parallel orientation of the 1,3‐butadiyne units. The reaction of 15b with concd. HCl in ethanol yielded 5,12‐dichloro‐2‐isopropyl‐1,2,3,6,7,8,9,10‐octahydrocyclonona[ e ]isoindole ( 16c ) and 5‐chloro‐2‐isopropyl‐2,3,6,7,8,9,10,11‐octahydrocyclonona[ e ]isoindol‐12(1 H )‐one ( 17c ). A mechanism for the reaction of 15b with HCl is proposed. The reaction of 15a with concd. HCl in ethanol gives 5‐chloro‐2‐isopropyl‐2,3,7,8,9,10‐hexahydrocycloocta[ e ]isoindol‐11(6 H )‐one ( 24c ). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)