Benzobicyclo octenone

Liu L, Ishida N, Murakami M (2012) Atom- and step-economical pathway to chiral benzobicyclo[2.2.2]octenones through carbon-carbon txmd cleavage. Angew Chem Int Ed 51(10) 2485-2488. doi 10.1002/anie.201108446... 

Scheme 12) (during the preparation of this manuscript, a new asymmetric reaction was reported [55]) [56]. A similar mechanism was proposed and benzobicyclo [2,2,2]octenone 63 was isolated in high yield (77-97%) and ee (80-93%). Thus far, this is a unique example of an intermolecularcarboacylatiOTi of alkenes via C-C bond activation. One year later, Louie and co-workers reported a nickel-catalyzed cycloaddition of 1,3-dienes with 3-azetidin(Mies and 3-oxetanones [57]. In their report, the combination of Ni(cod)2 and monodentate phosphine P(p-tolyl)3 was found to successfully couple 1,3-dienes and 3-azetidinones/3-oxetanones and afford eight-membered heterocycles in medium to good yield. It is interesting to note that only 2,3-substituted dienes were suitable substrates, primarily because of sterics (Scheme 13). 

Enantioselective Synthesis of Benzobicyclo[2.2.2]octenones via Asymmetric Alkene Insertion into a C-C Bond of Cyclobutanones... 

A class of benzobicyclo [2.2.2] octene derivatives is known to possess a variety of biological activities (Figure 8.4). For example, benzobicyclo[2.2.2]octenols 20 act as calcium channel blockers and amino-substituted benzobicyclo[2.2.2]octenes 21 work as y-secretase inhibitors. Benzobicyclo[2.2.2]octenone 23 serves as the... 

Murakami et al. reported a nickel-catalyzed alkyne/alkene insertion reaction into a C(carbonyl)-C(sp ) bond of cyclobutanones [21] and applied it to the enantioselective synthesis of benzobicyclo[2.2.2]octenones (Scheme 8.4) [22]. [2-f2] Cycloaddition of 1,2-divinylbenzene 24 with dichloroketene followed by... 

The conventional method to synthesize 23 required five steps starting from 1,4-benzoquinone and 1,3-cyclohexadiene four of the steps were used for functional-group manipulation (Scheme 8.5) [23]. Finally, it afforded only a racemic mixture that necessitated an additional resolution process in order to get an enantio-enriched or enantio-pure 23. Thus, the asymmetric alkene insertion of 3-(2-styryl)cyclobutanones significantly reduced the steps required for the synthesis of optically active benzobicyclo [2.2.2] octenones. 

The photoreaction of other bicyclo[2.2.2]octenones, and their congeners with more than one p,y-C-C double bond, have the possibility of dual deactivation pathways for example, ODPM and di-Jt-methane reaction upon excitation have been examined. > > - The benzobicyclo[2.2.2]octenones 122a and 122b are some of the earher examples that were found to follow the ODPM reaction pathway upon acetone-sensitized irradiation that involved the non-benzenoid C-C double bond to give the products 123a and 123b, respectively, albeit in low yield (Scheme 23). The bicyclo[2.2.2]octadienone 124, however, yielded a very small amount of ODPM product. The major product was due to di-Jt-methane reaction. ... 

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