Bicyclo decane-2,8-dione

On heating above 200 °C, 2,5-bis(trimethylsiloxy)tricyclo[4.4.0.02 5]decan-7-ones undergo a [2 4- 2] cycloreversion to form either 1,2-divinylcyclohexanes or 1,5-bis(trimethylsiloxy)cyclodeca-1,5-dienes. These are not stable at elevated temperatures and rearrange. After aqueous acidic workup, bicyclo[5.3.0]decene-2,5-diones 13 are isolated.45... 

Figure 11. Molecules that are chiral in the excited state only, (a) (lS,3R,7R,9S)-tricyclo-[7.3.0.03 7]dodecane-5,11 -dione in the electronic ground state, (RS), and in locally excited n ->Jt states, (.RS ) and (RS).5S (b) 3-(1nJt )-(lS,6R)-bicyclo[4.4.0.]decane-3,8-dione prepared by thermal decomposition of enantiopure 1,2-dioxetanes. 56...

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. 

On reaction of spiro[bicyclo[2.1.0]pentane-5,l -cyclopropane] with 4-phenyl-4/f-l,2,4-triazole-3,5-dione the bridge was cleaved and cycloaddition to the N-N double bond took place giving 4-phenyl-2,4,6-triazaspiro[cyclopropane-l,10 -tricyclo[5.2.1.0 ]decane-3, 5 -dione] in quantitative yield. 

Related cyclizations are observed in certain bicyclic diketones, converting them into tricyclic aldols. Deslongchamps and coworkers discovered that c -bicyclo[4.4.0]decane-3,9-dione is the minor isomer in equilibrium with its intramolecular aldol, the twistane derivative (123 equation 145). The equilibrium could be shifted completely to the aldol by acetylation. 

The MBH reactions of non-enolizable a-diketones precursors (Figure 1.4) with the activated olefins, e.g. acrolein, methyl acrylate and acrylonitrile, have been investigated systematically. The reaction of 3,3,5,5-tetramethyl-cyclopentane-l,2-dione (162) with acrolein and acrylonitrile, but not methyl acrylate, afforded the mono-a-hydroxyalkylation products in high yields. Other nonenolizable a-diketones, such as camphorquinone (159), homo-adamantane-2,3-dione (160) and bicyclo[ 3.3.2]decane-9,10-dione (161) reacted only with acrylonitrile, probably due to the hindered nature of the a-dicarbonyl compounds and the difference in steric demand between nitrile and ester. 

A novel properly of an electronically excited molecule can be chirality that exists only because of photoexcitation. Miesen, F. W. A. M. Wollersheim, A. P. P. Meskers, S. C. J. Dekkers, H. P. J. M- Meijer, E. W. /. Am. Chem. Soc. 1994,116,5129 reported the synthesis of optically pure 3-( n,Ji )-(lS,6R)-bicyclo[4.4.0]decane-3,8-dione, which is chiral only in the excited state. The chirality was detected in the circular polarization of chemiluminescence associated with its synthesis from an optically active 1,2-dioxetane precursor. 

An improved synthesis of mixed alkanone triperoxides has been reported. Ozonolysis of bicyclo[4,3,0]non-l(6)-ene gives diperoxide (107) as well as cyclonona-1,5-dione (107) was heated in decane to give a mixture of 1,8- and 1,9-cyclohexade-canediones (50%) together with a mixture of diketoheptadecanolides (16%). ° The thermal decomposition of some trisubstituted tricyclohexylidene triperoxides has been reported. The rate of decomposition of bis(cyclododecylidene)cycloalkylidene... 

C11H12O2, 3,3 -Spirobi(bicyclo[3.1.0]hexane)-2,2 -dione, 37B, 105 C11H13CI, (+)-l-Chlorotrishomobarrelene, 43B, 234 CliHi3N, 1-Cyanotetracyclo[3.3.1.1. 0 ]decane, 39B, 137 C1iH1ftClNO, 1-Methoxy-3-methyl-6-chloro-6-cyanobicyclo[2.2.2loctene, 43B, 235... 

Cl 2 18O3, cis-l-Oxa-7,7,10-trimethyldecalin-2,5-dione, 42B, 242 Cl2H18O3 r 3-Methoxy-trans-bicyclo[4,4,0]decane-l,3-carbolactone,... 

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