Undecadienone

The 1,2-addition of vinyllithium to the carbonyl group of dialkyl squarate-derived bicycloheptenones initiates a low-temperature anion-accelerated oxy-Cope rearrangement to afford bicyclo[6.3.0]undecadienone. H.W. Moore and coworkers accomplished the total synthesis of (+)-precapnelladiene using this methodology. ... 

Irradiation of (157) through Pyrex brings about decarbonylation and the formation of the tetraene (158) which on further irradiation using X,>220 nm gives a low yield of the (4 + 4)-adduct (159). The photodecarbonylation of e [Pg.65]

Using this method, 3-(2,2-dimethyl-3-vinylcyclopropyl)cyclohex-2-enone 11 or its 2-methyl derivative were prepared from lithium [c -(and-rra . )-2,2-dimethyl-3-vinylcyclopropyl]-phenylsulfanylcuprate (10) and 3-iodocyclohex-2-enone, or its 2-methyl derivative. Cope rearrangement of the resulting 1,2-divinylcyclopropanes gave bicyclo[5.4.0]undecadienones. ... 

Murakami and co-workers further developed this reaction to a [4+2+2] cycloaddition [46, 47]. Cyclobutanone (52) can be effectively coupled with 1,6-diyne (53b) to afford bicyclo[6,3,0]undecadienone 54b in excellent yield (91%). Two possible mechanisms were proposed for this transformation (Scheme 10). Either pathway leads to intermediate 57c, which upon p-C elimination and reductive elimination of the four-membered ring furnishes the final product. 

Singh, V. and Thomas, B., Studies on photoreaction of endo-tricydo[5.2.2.0 ] undecadienones in excited singlet state,/. Indian. Chem. Soc., 75,640, 1998. 

---