Cyclooctene tethered

Scheme 32 Stereoselective geometrical isomerization of cyclooctene tethered to the sensitizer.

Srinivasan and Ford [158] reported that epoxidation of cyclooctene using excess H202 was catalyzed by polymolybdate such as [Mo7024]6 tethered on the colloidal polymer with alkylammo-nium cations. Cyclooctene was oxidized to give 1,2-epoxy cyclooctane with >99% selectivity at 90% conversion for 24 h at 313 k ... 

Table4 Cyclooctene epoxidation with TBHP/MCM-spacer ligand-tethered Cp Mo(CO)3R complexes... 

The results for cyclooctene epoxidation with TBHP show that the method of heterogenisation plays a decisive role in the activity (Table 6). Indeed, the materials obtained from the complex grafted onto a fimctionahsed matrix (odd entries. Table 6) are less active (seen by comparing TOP values) than those synthesised via the tethering of fimctionahsed complexes on a mesoporous material (even entries. Table 6). 

In contrast, the intramolecular energy transfer in cyclooctene derivatives 63E-65E, which are tethered to benzoate, isophthalate, and terephthalate moieties through a (/ ,/ )-2,4-pentadiol linker, does not appear to be seriously affected by the steric bulk of 1-alkylation (Scheme 10) [50]. Upon irradiation at — 65°C, 63, 64, and 65 afforded ZJE ratios of 0.8,0.15, and 0.06, with diastereomeric excesses (des) of 33, 37, and 44%, respectively. 

The photoisomerization process of (Z)-cyclooctene (10), complexed by a modified P-cyclodextrin tethered to a benzoate sensitizer (35), has been described [88]. Several solvents were considered, with the best results obtained in a 50 50 mixture of water and methanol, in which a catalytic amount of the host/sensitizer led to a pss with an ElZ ratio of 0.8. This value far exceeded the usual pss ratio s reported for alkyl benzoate photoisomerizations of 10, which are typically 0.25-... 

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