2,3:5,6]Dibenzo[2.2.2]octa-2,5,7-triene (C2/c) and [2,3:5,6]dibenzo[2.2.2]octa-2,5-diene

Abstract

Two barrelene homologs are reported. Strain in the bicyclic framework of [2,3 :5,6]dibenzo[2.2.2]octa-2,5,7-triene, (I) (C 16 H 12 ), which is manifest in the deviations from ideality of the bond angles in the central bicyclic ring system and compression of the double bond [1.312 (3) A], is reduced in the more saturated derivative, [2,3:5,6]dibenzo[2.2.2]octa-2,5-diene, (II) (C 16 H 14 ), with the corresponding single bond being 1.5380 (19) A. The formation of isomorphs of (I) in both chiral (C2) and achiral (C2/c) space groups has implications for asymmetric syntheses involving solid (I) which rely on a non-centrosymmetric space group.