Maleinsäureaddukte an Phencyclon. [Heteropolare, XXVIII]

Carbonyl Bridge Compounds and Related Substances.

“…Relatively few cyclopentadienones are known (because they add to themselves, as will shortly become evident), and they are all polyarylated. They are obtained from 1,2-diketones and dibenzyl ketones, a reaction of aldol condensation investigated by Japp (60,62,63) (who, however, never isolated any of the cyclopentadienones) and by Dilthey (37)(38)(39)(40)(41)(42)(43)(44)(45)(46)(47)(48)(49)(50)(51). The most useful has been tetraphenylcyclopentadienone (47, 55); the name has been abbreviated to "tetracyclone" and the class as a whole is sometimes termed "cyclones.…”

“…In illustration, maleic anhydride in benzene or chlorobenzene adds to phencyclone; the addition product (XLIV) loses carbon monoxide and hydrogen, so that the dihydroanhydride (XLV) is never obtained completely pure. The aromatic derivative (XLVI), however, is easily prepared (41). for the temperature of decarbonylation is often below that at which they are formed; consequently, the polynuclear dihydro and aromatic fluoranthene derivatives are obtained directly (5,39).…”

Concerning the syntheses and structure of 2,3-dihydro-1,4-diphenyl-2,3-triphenylenedicarboxylic anhydride

“…of Vaughn-Williams' compound IV; however, its spectroscopic properties3 were not in agreement with the proposed structure. Other prospective preparations of IV (3)(4)(5) proved to be equally unproductive, yielding as they did, not IV, but rather the single products III (by the procedure of ref.…”

“…2 Author to whom correspondence should be addressed. 3 For example, the ir spectrum of the solid showed a strong bridged carbonyl absorption, but no high frequency absorption characteristic of an acid anhydride was observed. 4 Arbuzov et al ( 6) point out that the isolation of IV, rather than V, "presents great difficulty, for the decarbonylation occurs at a high temperature, at which the elimination of hydrogen is already beginning.…”

“…(Could not the product have structure VI, for example?) Dilthey et al (3), who first assigned structure IV to the product obtained from the thermally induced decarbonylation of adduct III, based their assignment on elemental analysis and (apparently) on the assumption that a direct analogy existed between the thermal behavior of III and that of other carbonyl-bridge compounds. Since then, two publications have appeared (in addition to Vaughn-Williams') that refer to the preparation of the Dilthey et al decarbonylation product.…”