Die Synthesen der Propellane 7 -9, die eine Benzol-Dewarbenzol-Struktur besitzen, werden be-
.2]propella-3,8,lO-trieneThe syntheses of the propellanes 7-9, which have a benzene-Dewar-benzene structure, are described. As a second example of a 1 ,rl-bridged Dewar-benzene, the crystal and molecular structure of 1 ',8': 3.5-naphtho[5.2.2]propella-3,8,lO-triene (9) is elucidated by X-ray structure analysis. 9 has a long central bridge bond of 1.565 A, which, however, is clearly shorter than the corresponding bond of 3,4: 5,6-dibenzo[6.2.2]propella-3,5,9,1l-tetraene (10: 1.586 A), due to the smaller C,-bridge. The dihedral angle of 116.6" between the cyclobutene rings of the Dewarbenzene system of 9 is insignificantly larger than the analogous angle of 10 (1 15.9'). The molecule lies on a crystallographic mirror plane.Bei der von uns ausgefiihrten Synthese') von 3,4: 5,6-Dibenzo[6.2.2]propella- 3,5,9,l ¶-tetraen (10)