Fluorenes, epoxidation

Epoxidation of substituted spiro[cyclopentane-l,9 -fluorene]-2-enes 68 with a peroxidic reagent was studied [98], The spiro olefins react with m-chloroperbenzoic acid (mCPBA) in chloroform at 3 °C to give a mixture of the epoxides. In all cases (2-nitro (68b), 4-nitro (68c), 2-fluoro (68d) and 2-methoxyl (68e) groups), the iyn-epoxides, i.e., the syn addition of the peroxidic reagent with respect to the substituent, is favored. For example, for 6 nsyn anti = 63 31 for 68c syn anti = 65 35. Thus, a similar bias is observed in both the reduction of the carbonyl derivatives of 30 and the epoxidation of the derivatives of 68. 

In the epoxidation of an olefin with a peracid, the occupied n orbital of the olefin group HOMO) interacts with the vacant orbital (LUMO) of the peracid [143, 144]. The higher-lying aromatic n orbital of the substituted fluorenes (69) can interact with the orbital in a similar manner to spiro conjugation (Fig. 12). 

Monooxygenases. Under nonlignolytic conditions, arene monooxygenase and epoxide hydrolase systems may function to produce trani-dihydrodiols. Hydrogen abstraction mediated by the lipid peroxidase system may operate, for example, in the formation of fluorene-9-one from fluorene by Ph. chrysosporium (Bogan et al. 1996). 

POLYHYDROGEN FLUORIDE REAGENT 1-FLUORO-ADAMANTANE. Dichloroalkane synthesis is shown in cis-DI-CHLOROALKANES FROM EPOXIDES cis-1,2-DICHLORO-CYCLOHEXANE. Nitrile functionality can be introduced from a ketone, as in NITRILES FROM KETONES CYCLOHEXANENITRILE, or from a reactive diene, as shown in 2,3-DICYANOBUTADIENE AS A REACTIVE INTERMEDIATE BY in situ GENERATION FROM 1,2-DICYANO CYCLOBUTENE 2,3-DICYANO-1,4,4a,9a -TETRAHYDRO-FLUORENE. 

The preparation and properties of (9-oxo-9//-fluoren-2-yl)phenyliodonium hexafluoroantimonate (14) as a new photoinitiator for the cationic polymerization of epoxides have been reported [37]. Compound 14 was prepared by the reaction of (diacetoxyiodo)benzene with fluorenone followed by treatment with sodium hexafluoroantimonate (Scheme 7.3). Photoinitiator 14 has the advantage of intramolecular photosensitization and it is a more effective initiator than the conventional iodonium salts [37]. 

Fluorenyl Carbanions. Salts of fluorene (pifa 23) are more hindered and less reactive than many other organometallic initiators. Fluorenyl carbanions can be readily formed by metalation of fluorenes with alkali metal derivatives, as shown in equation 18. Carbanion salts of 9-methylfluorene are preferable to fluorene, since the latter generate chain ends that contain reactive, acidic fluorenyl hydrogens that can participate in chain transfer reactions. Fluorenyl salts are useful initiators for the polymerization of alkyl methacrylates, epoxide, and thiirane monomers. 

HAR 01] Hartwig a., Harder A., Luhring A. et al.., 9-Oxo-9H-fluoren-2-yl)-phenyl-iodonium hexafluoroantimonate(V) - a photoinitiator for the cationic polymerisation of epoxides , European Polymer Journal, vol. 37, pp. 1449-1455,2001. 

Thus free radicals may readily be involved in a photo-epoxidation, and when they are they can be detected by establishing the chain character of the reaction and its response to initiators. If the example of 9-methoxymethylene-fluorene is of general significance, we may suspect that reactioqs leading cleanly to epoxides as single products will not be found to proceed through free radicals. 

A mixture of hydrocarbons can be separated by three selective adsorbents molecular sieves which retain the n-paraffins, mercuric perchlorate which adsorbs the unsaturated compounds, and a stationary liquid phase which retains the aromatic hydrocarbons. Boric acid on a stationary phase such as Chromosorb P is used for the removal of alcohols from a mixture of organic compounds, the products are nonvolatile esters. A similar technique was used for removal of terpene alcohols from a mixture of terpenoids. Acids can be adsorbed on potassium hydroxide deposited on quartz powder. This technique was found to be suitable for the analysis of compounds having active hydrogens such as fluorene, indene, carbazole, indole, and pyrrole as well as steroids such as estrogens and ketosteroids. o-Dianisidine quantitatively subtracts aldehydes, ketones, and epoxides, and phosphoric acid subtracts epoxides. 

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