The photolysis of methylenecyclobutenone in the presence of benzophenone or oxygen affords the one carbon diminished product, methyl 4,4-diphenyl-2-diphenylmethyl-2,3-butadienoate. The reaction pathway is discussed.

Heating of 3,3,4,4-tetrabromo-1,2-bis(diphenylmethylene)cyclobutane in dichloroacetic acid afforded bridgehead olefin, 7-bromo-1,4,8-triphenyl-2,3-benzobicyclo[3.3.0]octa-2,4,7-trien-6-one, and spiroketone, 2-bromo-2′,3-diphenylspiro[1H-indene-1,1′(4′H)-naphthalen]-4′-one (13). Mechanism of the reaction was discussed. X-Ray structural study of the spiroketone 13 was also reported.

The photocyclization of the title compound afforded 14-hydroxy-4b-phenylbenz[c]indeno[2,1-a]fluoren-13-(4bH)-one, which is easily isomerized to 4b,13b-dihydro-4b-phenylbenz[c]indeno[2,1-a]fluorene-13,14-dione. The hydrogenation of both compounds gave anti-4b,8b,13a,13b-tetrahydro-4b-phenylbenz[c]indeno[2,1-a]fluorene-13,14-dione.

No abstract

Upon the AlCl3-catalyzed cyclization of the title biindenone (1) into benz[c]indeno[2,1-a]fluorene-13,14-dione (2) and 3,3′: 3,3′-di(o-phenylene)-2,2′-biindenylidene-1,1′-dione (3), the 2:3 ratio increased when the reaction temperature was raised and decreased when the polarity of the solvent was increased.