Tricyclo dodeca-2,5,7,10-tetraen

Benzo-12-oxa-3,5/,4,7-trithia-4,6-diaza-tricyclo]7.2.1.02-8 dodeca-2, 4,5,10-tetraene... 

Diaza-3,9-diazonia-2,8-diborata-tricyclo-[7.3.0.03,7 dodeca-3,5,9,1 l-tetraene... 

Central to the interconversions of the (CH)i2 hydrocarbons are the [12]annulenes, which are non-aromatic, and the benzene dimers. The cis,transycis,trans,cisytrans-[12]annulene appears to have been generated by photolysis of cis,syn,cis-tricyclo[8.2.0.0 ]dodeca-3,5,7,ll-tetraene at — 100°C (Scheme 13.3). ... 

The stereochemistry of the former product was not assigned, but later, the exo-isomer was synthesized and found to be identical to the product generated from the 8200 material. Benzene might arise from the bicyclo[6.4.0.]dodeca-2,4,6,9,ll-pentaene which could be formed by a forbidden disrotatory retro cyclobutene electrocyclization of starting material, and at least two paths to the tricyclo[4.4.2.0]-tetraene can be envisioned. These are a 1,5-shift of the cyclobutene ring and... 

Tricyclo[7.3.0.0" ]dodeca-2,5,7,10-tetraene was prepared in the hope of revealing a degenerate 3,3-shift, which in this case must occur via a boat-like transition state. However, upon heating the material at 141°C, no proton or carbon interconversion was found in the NMR (Scheme 13.18). ... 

The interesting p,/7 -benzene dimer, tricyclo[4.2.2.2 ]dodeca-3,7,9,ll-tetraene, has apparently not been synthesized, but tetramethylene and benzo derivatives have been prepared. These undergo a 3,3-shift to the syn,o,o -hQnzQxvQ dimer at room temperature (Scheme 13.20). 

The conversion of (298) into (300) upon gas-phase thermolysis occurs by a Cope rearrangement and not by a [1,3] carbon shift or a bisallyl radical mechanism. Thus, similar treatment of (299) affords only (301). Rearrangement of 3-oxobicyclo-[3,2,l]oct-6-ene to 3-oxobicyclo[3,3,0]oct-6-ene occurs only at much higher temperature and presumably by way of a non-concerted mechanism. The nickel-catalysed reaction of norbornene with butadiene affords the 1 2 cxo-adduct (302) which upon thermolysis is converted into the valence isomer (303). Concerted and non-concerted Claisen-type rearrangements have been observed in the A, -phosphorin series. Tricyclo[7,3,0,0 ]dodeca-2,5,7,10-tetraene (304), which is available in six steps starting from bicyclo[3,3,0]octa-3,7-dien-2,6-dione, appears to be an essentially static structure (as assessed by n.m.r. spectroscopy) up to 141 The slow... 

Ranninger, M., S. Carrera, and S. Blanco. 1985. Crystal and molecular structure of the tetrachloropalladate of the dication meso-3,7-diazonia tricyclo[4.2.2.22,5]dodeca-3,7,9,ll-tetraen-4,8 diamine obtained by coupling reaction of 2-aminopyridines. 

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