Octa-3,7-dien

To a suspension of NBS (15.45 g, 87 mmol) in CC (150 mL) was added 8-methoxy-7-azabicyclo[4.2.0]-octa-3,7-diene (11.36 g, 83 mmol), followed by DBPO (0.3 g). The mixture was heated at reflux with stirring and concomitant irradiation with a sunlamp under a N2 atmosphere. After 10 min, the mixture was cooled to rt, filtered to remove succinimide, and evaporated. The viscous, slightly brown oil was employed without further purification. 

As is the case for [2 + 2] cycloaddition reactions (15-61), certain forbidden electrocyclic reactions can be made to take place by the use of metallic catalysts." An example is the silver ion-catalyzed conversion of tricyclo[4.2.0.0. ]octa-3,7-diene to cyclooctatetraene " ... 

Octan-l-ol acetate Rh Oct-trans-2-en-l-al Rh Octa-2-6-diene-l-8-diol, 2-6-dimethyl Rh Octa-3-7-diene-l-6-diol, 2-6-dimethyl Rh Octa-3-cis-6-dien-l-al, 3-7-dimethyl Rh Octa-d-tram-h dien-l-al, 3-7-dimethyl Rh Octa-traTiS 2 CiS 6 dien l ol, 3-7 dimethyl 8-hydroxy, P-D-glucopyranoside Rh 5.2 °... 

Similarly, cycloaddition of 4-toluenenitrile oxide to cyclobutadiene gave a 2 2 adduct,26 whose configuration was not determined, but it is believed that this adduct was formed from the cycloaddition of nitrile oxide to the C —C double bonds of the major dimer of cyclobutadiene, namely A > -tricyclo[4.2.0.02 5]octa-3,7-diene.26... 

Cyclobutadienes represent very reactive alkenes that undergo both [2 + 2] as well as [4 + 2] cycloadditions. Both the cyclodimerizations, mixed [2 + 2] cycloadditions and Diels-Alder reactions of these reactive species have been reviewed (see Houben-Weyl, Vols. 4/4, p 231 and E 17 f, Section 10B). In most instances the initially formed cyclodimer is tricyclo[4.2.0.02-5]octa-3,7-diene (36) and has the all cis-syn configuration. This is attributed to the concerted [4n -I- 2n] cycloaddition mechanism in which stereochemical control is affected by secondary orbital interactions. 

MANGANESE COMPLEXES OF OFCOT AND PERFLUOROTRICYCLO[4.2.0.02S]OCTA-3,7-DIENE... 

A second valence isomer of 108a can be synthesized by reaction of Na+[Mn(CO)j]- with a fi-octafluorotricyclo[4.2.0.02>3]octa-3,7-diene 53, to give the tricyclic product 113a (184). The molecular structure of 113a is... 

Me3Si)2S in the presence of Me3SiOTf induces the rearrangement of bis[(Mes)metha-noyl] bicyclo[2.2.1]hept-5-enes to 2-oxabicyclo[3.3.0]octa-3,7-dienes (equation 20)38. 

Erhitzen (oder UV-Bestrahlung) der 2,2,2-Triorgano-2A5-homocubane fiihrt unter Abspaltung des entspre-chenden Phosphans zu syn-Tricyclo[4,2.0.0.2 5]octa-3,7-dien, das sich zum Cyelooctatetraen umlagert2 ... 

Using comparable experimental conditions, Bollinger and Olah examined the protonation of syti- and anri-octamethyltricyclo[4.2.0.02,s ]octa-3,7-diene, octa-methylsemibullvalene, and octamethylcyclooctatetraene and found in every case that the major species produced was the octamethylbicyclo[3.3.0]octadienediyl dication (297).312)... 

Dioxonia-l, 5-diaza-2,6-diborata-bicyck [3.3.0]octa-3,7-diene... 

Azocin 3,8-Dimethyl-2-methoxy-V/ld, 448 E9d, 512 (8-OR-1.6-R2—7-aza-bicyclo[4.2.0]octa-3,7-dien/NBS NaOR)... 

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