SYNTHESIS OF SUBSTITUTED DIBENZOEQUINENES

The naphthalenophanes with four donor groups such as 14,17-tetramethox y-anti-[2.2](1,4)naphthalenophane (10), the corresponding syn-isomer 1 0a, and ,14,17-tetramethy1-anti-[2.2](1,4)naphthalenophane (17) togeth er with the naphthalenophanes with four acceptor groups, 7,14,17-tetra cyano-anti-[2,2](1,4)naphthalenophane (21), and 16-tetracarbethoxy-ant i-[2.2](1,4)naphthalenophane (23), belonging to point group C-2h for t he anti-and C-2v for the syn-isomer, have been synthesized following m ostly known procedures. Furthermore, the preparation of dicarbethoxyna phthaleno-[2.2](1,4)naphthalenophane (27) and aphthaleno-anti-[2.2](1, 4)-5,8-naphthochinonophane (28) with one donor and one acceptor substi tuted ring supplements the series. The irradiation of 10, 21, 23, and 27 yields 2,2',5,5'-tetramethoxydibenzoequinene (30), 2,2',5,5'-tetrac yanodibenzoequinene (31), 3,3',4,4'-tetracarbethsxydibenzoequinene (32 ) and 3,4-dicarbethoxydibenzoequinene (33). Structural investigations on 30 by means ofthe X-ray method show a strong folding of the cyclobu tane rings. The average bond length of the four-membered rings in 30 w as found to be 1.579(2) Angstrom. The values obtained for the bond len gths and bond angles resemble those of the parent system 2. Long ethan o bonds (1.556-1.591 Angstrom) in the bridges were found in the synand anti-naphthalenophanes 10a, 14, and 17 by means ofX-ray structure ana lysis.