Cycloheptatriene, singlet oxygen

The norcarane peroxides 18 are derived from 7-substituted 1,3,5-cycloheptatriene via the singlet oxygen-diimide route (equation 13)30). 

Alternatively, the (2 + 4)-tropilidene endoperoxide, which is the major product in the singlet oxygenation of cycloheptatriene 30 a) affords on diimide reduction the desired bicyclic peroxide 20. The double bond in the two-carbon bridge is reduced selectively, but on exhaustive treatment with excess diimide, the fully saturated substance is obtained. A number of substituted derivatives have been prepared in this way30). 

Reaction with eycioheptatriene Reaction of cycloheptatriene with singlet oxygen leads to a mixture ( 1 1) of 2 and 3. Formation of 2 results from the unusual [2 + 6] addition. Some transformations of 2 and 3 have been reported. 

A review on the synthesis of the carbopenam antibiotics has appeared. The l-azabicyclo[2.1.0]pentane skeleton has been reported this year, as is the first readily performed displacement of 4-acetoxyazetidinone with enolate anion equivalents. Most notable, however, is the preparation and utilization of a series of 1,2-diazetidinium ylides, which appear to have great potential in heterocyclic synthesis. The one missing cyclo-adduct of singlet oxygen and cycloheptatriene has now been described, as has the first, highly unstable, benzodithiet. ... 

Bridged peroxides- Addition of singlet oxygen to unsaturated carbocycles and heterocycles continues with studies of 7-substituted cycloheptatrienes. 9 spiro-cycloheptadienylcycloheptatrienes 130 methoxycyclooctatetraenes. ... 

Bridged Peroxides.—Routine procedures have been extended to the synthesis and characterization of photo-adducts of singlet oxygen with cyclo-octa-1,3,5-triene, cycloheptatrienes, 3,5-cycloheptadienone, cyclohepta-1,3-dienes, ° naphthalenes, anthracenes, a-pyrones, pyrazines and pyrimidines,imidazoles, and indenes. Transformation of some of these... 

Several syntheses of closely related compounds have appeared this year. Adam and Balci have accomplished a stereoselective synthesis of the three possible stereoisomers of cycloheptatriene-1,3,5-trioxide. Although the all-cw compound was known, their route gave the individual isomers by judicious choice of the sequence of singlet oxygenation, endoperoxide-dioxide rearrangement and peracid oxidation. Similarly, the three isomers of trioxatropone (24) have been prepared by Prinzbach and co-workers,by making use of the halohydrin... 

From 1,3,5-cycloheptatriene and l,3,5-cyclooctatriene, the respective bicycUc and tricyclic endop-eroxides were obtained in 93 7 and 80 20 ratios, respectively. From cyclooctatetraene, no adduct with the bicychc valence tautomer was obtained, but 26% of the bicychc [4 -I- 2]-adduct was isolated. The valence tautomer of cyclooctatetraene, however, could be prepared independently and afforded the expected tetracychc endoperoxide with singlet oxygen. ... 

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