A STABLE DERIVATIVE OF CYCLOOCTATRIENYNE. SYNTHESIS AND CRYSTAL STRUCTURES OF 1,4,7,10-TETRAMETHYL-5,6-DIDEHYDRODIBENZOCYCLOOCTENE AND 1,4,7,10-TETRAMETHYLDIBENZOCYCLOOCTENE

Article abstract of DOI:10.1016/S0040-4020(01)87466-4

A stable derivative of cyclooctatrienyne (1), namely 1,4,7,10-tetramethyl-5,6-didehydrodibenzocyclooctene (3) has been synthesized and fully characterized.X-Ray crystallographic analyses indicate that 3 adopts a "butterfly" conformation intermediate between those of virtually planar 5,6-didehydrodibenzocyclooctene (2) and tub-shaped 1,4,7,10-tetramethyldibenzocyclooctene (16).The methyl substituents effectively shield the otherwise rather exposed strained triple bond of 3 and kinetically stabilize it against dimerization and/or oxidation.