Bicyclo decan-9-ones yield

Intramolecular cyclopropanation of 4-aryl-1 -diazo-2-butanones 240 allows construction of the bicyclo[5.3.0]decane framework 12). In a reaction sequence analogous to that described above for the intermolecular ketocarbenoid reaction, bicyclo-[5.3.0]deca-l,3,5-trien-8-ones 241 are formed. They rearrange to the conjugated isomers 242 at the high temperatures needed if the reaction is catalyzed by copper 2311 or CuCl 232), but can be isolated in excellent yield from the Rh2(OAc)4-promoted reaction which occurs at lower temperature 233... 

In summary, intramolecular reactions of a considerable variety of diones provide interesting mechanistic questions as well as a route forj construction of four- and five-membered rings in high photochemical and chemical yields. Except for a synthesis of cis- and trans-bicyclo[7.1.0]decan-2-one from cyclodecane-1,2-dione 122), this potential has been ignored. 

It is noteworthy that irradiation of tetracyclo[6.2.0.0 . 0 ]decan-9-one resulted in cycloreversion and formation of ketene and vinylcyclopropane tricyclo[5.1.0.0 ]oct-5-ene instead of ring cleavage and decarbonylation. A C-C double bond a to a cyclopropane ring also resulted when spiro bicyclo[2.2.1]hept-5-ene-7,l -cyclopropane -2-one eni/o-epoxide underwent a deep-seated rearrangement upon irradiation through Corex to give 5-oxo-spiro[2.4]hept-6-ene-4-ylacetaldehyde in 50% yield. ... 

Similarly, 10-(4-mcthylphenylsulfonyl)bicyclo[6.2.0]decanol undergoes ring expansion-contraction upon exposure to boron trifluoride or alumina yielding /erm-fused bieyclo[7.1.0]decan-2-one (10)63. 

The cationic, goid(I)-catalysed tandem heterocyclization/3 + 2-cycloaddition of 2-(l-alkynyl)-2-alken-l-ones (1) with 3-styrylindoles (2) yielded highly substituted cyclopenta[c]furans (3) in a one-pot reaction under mild conditions. The expected cyclohepta[c]furans (4) were not isolated (Scheme 1). The 1,3-dipolar cycloaddition of 3-oxidopyridinium betaines with pentafulvenes produced a variety of bicyclo[6.3.0]undecanes and bicyclo[5.3.0]decanes via 3 + 2- and 6 + 3-cycloadditions. ... 

Bicyclo[5,3,0]dec-l(7)-en-2-one was obtained by anodic oxidation of bicyclo-[4,4,0]decane-l,6-diol in methanol containing tetraethylammonium p-toluenesul-phonate. The dicarboxylic acid (68), used in the synthesis of methymycin, was obtained by oxidative cleavage of 8-formylbicyclo[4,2,l]nona-2,4-dien-7-one. Autooxidation of (-t-)-car-3-ene in the presence or absence of cobalt stearate gave a complex mixture of products including eucarvone (up to 11.5 %) and 3,6,6-trimethylcyclohepta-2,4-dienone (up to 48 %). 3-Methylene-4-cholestene gave a 40% yield of 3,3-diazido-A-homochoIest-5-ene when treated with Pb(OAc)4 (N3) . ... 

Cyclopentanone annelation via thermolysis of trimethylsilyl enol ethers of cyclopropyl methyl ketones has been studied a good yield of bicyclo[5,3,0]decan-8-one was obtained from (321 R = Q=CH2)OSiMe3 R = H), but only a low yield of bicyclo[5,3,0]decan-9-one was obtained from [321 R = H, R = C(=CH2)-... 

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