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The photochemical addition reaction of cycloheptatriene with p-benzoquinone and 1,4-naphthoquinone yielded the spiro-ethers having 7-oxa-bicyclo[4,2,1] nonadiene moiety by the characteristic (6+2)π addition process. The latter quinone further produced the carbocyclic (2+2)π - and (6+2)π cycloadducts. Either (4+2)π adducts or dioxetanes were undetectable in both cases. The photoadducts were stable under their formation conditions, showing no tendency to cause the isomerization.

Two tetrapropyl derivatives of dicyclohepta[5,6:b]pyrazino[2,3-g]quinoxaline-3,11-dione and 9,11-dipropylcyclohepta[5,6]pyrazino[2,3-b]phenazin-10-one, revealed the J-band in cone H2SO4. On the other hand, 2,3-diphenylcyclohepta[b]pyrazino[2,3-g]quinoxalin-9-one formed a non-J-aggregate, but benzo[g]cyclohepta[b]quinoxalin-9-one formed no aggregate. A pyrazinoquinoxaline framework is required for the aggregation.

Laser excited fluorescence spectra and dispersed fluorescence spectra of 3-isopropyltropolone have been measured in ultracold gas phase by a supersonic expansion. The tunneling splittings in the zero-point level of the S1state have been determined to be 58 and 14 cm−1for normal and deuterated species, respectively.

Two new types of liquid crystals, 5-(4-alkanoylaminophenyl)-2-alkanoylaminotropones and 5-(4-alkanoylaminophenyl)-2-alkanoyloxytropones, were prepared. The former showed the smectic A phase and the latter did the smectic A and C phases. The 1H NMR spectra indicated the former to be in intramolecularly hydrogen-bonded L-shaped alignment.

2,3-Bis(methoxycarbonyl)-7-oxabicyclo[2.2.1]heptadiene gave the [4+2] cycloadducts with 8,8-dicyanoheptafulvene and cycloheptaf[b]-furan-2-ones. This mode is different from the [8+2] cycloadduct formations with the previously studied enamines and alkoxyethenes. The results from MNDO calculations were in accord to the observed modes of the cycloadditions. Thermolysis of the cycloadducts gave the methylidene derivatives of “homobarrelenes”.

Thermal reactions of tropone with furan and 2-methoxyfuran gave mainly the endo-[4+2] cycloadducts at 3000 bar. In the latter case, the products further reacted with tropone to yield 2:1-adducts. The NMR spectral data defined their stereochemistry; predominant formation of endo-adduct is rare in the Diels–Alder reaction of furans. This must be due to the conditions employed, under which the cycloreversion is prevented.

During the preparation of 2-(o- and p-nitrobenzyloxy)tropones from o- and p-nitrobenzyl chlorides and potassium tropolonate, a concomittant formation of α-hydroxylated 2-(o- and p-nitrobenzyl)tropones and 3-(o- and p-nitrobenzyl)tropolones was recognized. This alkali-promoted reaction has no precedent analogy in the troponoid chemistry. From the 2-(p-nitrobenzoyl)tropone, a tetrahydrobenzodiazaheptalenone, 6-(p-nitrophenyl)-5,7,11a,12-tetrahydrocyclohepta[b](1,5)benzodiazepin-7-one, was prepared.

Thermal rearrangement of 2-(benzyloxy)-3-bromotropone to 2-(benzyloxy)-7-bromotropone, regarded to be the first [1,9] sigmatropic rearrangement, was analyzed by high-pressure kinetics. ΔV≠for the process were shown to be −11.1 and −10.1 cm3mol−1in isopropylbenzene and 1-hexanol, respectively. The figures confirmed the concerted nature of the rearrangement, and were similar to various [1,5] sigmatropies of cyclopentadienes.

Anodic oxidation of 2,7- and 2,3-dimethoxytropones gave the correspondong isomeric o-tropoquinone bisacetals, 2,2,7,7-tetramethoxycyclohepta-3,5-dienone and 2,2,3,3-tetramethoxycyclohepta-4,6-dienone in good yields. By H2SO4-treatment in AcOH–Ac2O, former afforded 4-acetoxy-2,7-dimethoxytropone, 2,5-diacetoxy-7-methoxytropone and 4,5-diacetoxy-3-methoxytropone, latter did no such product. Similar oxidation of 2-bromo-7-methoxytropone gave alternative p-tropoquinone bisacetal derivatives.

The planar and symmetrically conjugated π-system, dicyclohepta[5,6:b]pyrazino[2,3-g]quinoxaline-3,11-dione, showed a narrow and intense absorption band and resonance fluorescence in cone H2SO4solutions as low as 10−7M. These observations show the formation of the J-aggregate. A remarkable solvatochromism was also noticed in organic solvents (476 nm in CHCl3and 547 nm in DMF).

The Diels–Alder adduct of tropone with 2,3-bis(methoxycarbonyl)-7-oxabicyclo[2.2.1]hepta-2,5-diene formed homobarrelenone by heating at ca. 130 °C. Similarly prepared were 1-hydroxy-, 3-methoxy-, 1-chloro-, and 3-chlorohomobarrelenones. High-pressure cycloaddition improved the yields of the Diels–Alder adducts.

Condensation of p-tropoquinones and 5-hydroxytropolones, preferably by acid, yielded dicycloheptafurandione derivatives, which have the same carbon framework with utahin, a naturally-occurring dimeric tropolone. Partial oxidation of 5-hydroxytropolones and partial reduction of p-tropoquinones respectively yielded the condensates. This should exemplify the “phenol oxidation” in troponoids.

Thermal addition reaction of cycloheptatriene with some aromatic quinones was studied. In addition to ordinary Diels–Alder adducts, identified in the products were 2,3-ditropylcyclohex-5-ene-1,4-diones which were shown to be formed after series of tropylation, dehydrogenation, and further tropylation processes.