Tricyclo octa-3,6-diene semibullvalene

A very rapid degenerate Cope rearrangement was observed for tricyclo[3.3.0.0 ]octa-3,6-diene(semibullvalene), 301. The H-NMR spectrum showed type A protons at 5.08 ppm, type B at 4.17 ppm and type C at 2.97 ppm and was unchanged between — 110° C and -I-117° C three absorptions only were shown in the C-NMR spectrum. ... 

When a mixture of benzene and perfluorobutyne was irradiated in a Vycor tube with 253.7 nm light, slow formation of at least eight compounds was detected by gas chromatography. The major compound was l,2-bis(trifluoromethyl)cycloocta-l,3,5,7-tetraene (10, 40%), accompanied by three isomeric bis(trifluoromethyl)tricyclo[3.3.0.0 ]octa-3,6-dienes (semibullvalenes) 11-13 in 25, 12 and 5% yield, respectively. ... 

One of the first examples of the di-7t-methane rearrangement was found in the photochemical conversion of bicyclo[2.2.2]octa-2,5,7-triene (barrelene, 1) to tricyclo[5.1.0.0 ]octa-2,5-diene (semibullvalene, 2). ... 

Next we will consider some examples from the photochemistry of COT. Although the photochemistry of COT has not been studied in great detail and little is known about the mechanistic details of the various photoprocesses, a number of photoproducts have been identified under various conditions benzene and acetylene among other hydrocarbons, as well as 3,6-dihydropentalene and its isomers, semibidlvalene and cuneane, while photolysis of tricyclo[3.3.0.02 ]octa-3,7-diene led to semibullvalene and COT in a 1 2 ratio. We will deal with semibullvalene (5), tricyclo[3.3.0.0 ]octa-3,7-diene (6), cuneane (7), and 3,6-dihydropentalene (8) as summarized in Scheme 6.2a. In addition, we will consider the hypothetical... 

Figure 6.5 Phase-rule loops for photoreactions of COT. (a) The COT o semibullvalen conversion. All reactions in the loop constructed from the two Kekule forms of COT and semibullvalene are of Htickel type from the number of pairs of electrons that exchange spin, it is seen that the loop is ip and encloses a conical intersection, (b) Loop for the COT tricyclo[3.3.0.0 ]octa-3,7-diene conversion...

Cyclooctatetraene (COT), a An non-aromatic hydrocarbon, is only one of the many (CH)s compounds, but it is a central character. The other isomers, many of which interconvert with COT by thermal and photochemical pathways, include bicyclo[4.2.0]octa-2,3,7-triene (BOT), semibullvalene (SB), barrelene (B), tricyclo[3.3.0.0 ]octa-3,7-diene (TOD), the cyclobutadiene dimers (CBD), tetracyclo[4.2.0.0. " 0 ]oct-7-ene (TOE), cubane (C), tetracyclo[4.2.0.0. 0 ] octene - the intramolecular Diels-Alder isomer of BOT (IDA), tetracy-... 

Miller LS, Grohmann K, Dannenberg JJ et al (1981) Semibullvalenes. 1. synthesis and crystal strucmre of 1,5-Dimethyl- 2,4,6,8-tetrakis (carbomethoxy) tricyclo-[3.3.0.0 ] octa-3,6-diene-A donor- acceptor- substituted semibullvalene. J Am Chem Soc 103 6862-6865... 

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