Quadricyclane, insertion

Parent cyclopropenylidene 390 has been generated recently from flash thermolysis of the quadricyclane 394 and trapped in an argon matrix at 10 K. Compound 390 displays an infrared spectrum in accord with theory and provides propynylidene 395 upon irradiation reaction with water leads to insertion products 396 and 397. 

Difiuorocarbene underwent addition to quadricyclane to give enr/u-6-(2,2-difluorovinyl)bi-cyclo[3.1.0]hex-2-ene together with three other products in 3% yield.The proposed formation of an insertion product into one of the cyclopropane C — C bonds was not verified in this reaction, but was observed in the reaction with other carbenes such as dichlorocarbene and bis(methoxycarbonyl)carbene. The major product with these carbenes possessed a bi-cyclo[3.2.1]octa-2,6-diene structure as the result of the insertion of the carbene into the cyclopropane bond next to the methylene bridge. ... 

Cassar and Halpem showed that [RhCl(CO)2]2 inserts into the strained a bond of quadricyclane [Eq. (6.109)] ... 

The Ag+ ion-catalyzed reaction of a quadricyclane derivative also appears to proceed through initial C-C bond insertion [Eq. (6.110)] ... 

The catalytic rearrangement of strained alkanes is common. Cassar and Halpern showed that in the [RhCl(CO)2]2-catalyzed rearrangement of quadricyclane to norbornadiene, the admission of CO led to the formation of an acyl complex that seemed to be formed by trapping the initial oxidative addition product by a migratory insertion (equation 28). On the other hand, the Ag -catalyzed rearrangement of strained alkanes goes via carbonium ion intermediates which can be trapped by such nucleophiles as MeOH. ... 

The same aldehyde is formed in the oxygenation of quadricyclane catalyzed by cytochrome P-450 [88]. The mechanism of the cytochrome P-450-catalyzed reaction has been reported as follows the oxygenation is initiated by one electron transfer from quadricyclane to an electron deficient iron-oxene intermediate, which is followed by insertion of an oxygen atom into a C-C bond rather than a C-H bond. The electron transfer from substrate to the iron-oxene intermediate may be reasonable because of a high ionization potential of quadricyclane. Since the diagnostic aldehyde is a sole product in both sMMO and cytochrome P-450 systems, it is likely that the same reaction mechanism is applicable to these two enzymatic reactions. A plausible mechanism for the sMMO-catalyzed oxygenation of quadricyclane is shown in Scheme 4. 

Mono insertion of carbon dioxide also occurs into the intermediate 101 of the reaction between quadricyclane and [(bipy)Ni(cod)L to give the metallacycle 102". ... 

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