Benzene derivatives, formation from furans

Unusually high abundances of water-soluble compounds such as benzene, toluene, xylene, and furan have been reported in some inclusion oil samples, particularly those lean in petroleum inclusions [81]. It has been well established that formation waters in oil fields contain water-soluble organic compounds due to partitioning between the oil and water phases [92-94]. One explanation for water-soluble compounds in fluid inclusions is that they derive from aqueous inclusions that typically co-occur with oil inclusions in petroleum reservoirs thus, the chemical composition of the inclusions partially reflects the composition of the water phase in the reservoir [81]. Fluid inclusion oils that are anoma-... 

The intramolecular (4n + 4ti) photoaddition of furan-pyran-2-one bichromo-phores [e.g. (38) to give (39)] is potentially useful as an approach towards the fusicoccane/ophiobolane skeleton (Chase et al.), and the formation of (40) from the irradiation of (41) constitutes the first example of a (47t + 4ji) photocycloaddition of an enone to the benzene ring (Kishikawa et al.). Wender et al. continue to report elegant new applications of the intramolecular meta photocycloaddition of 5-phenylpent-l-ene derivatives and have described the synthesis of cis,cis,cis, traMi-[5,5,5,5]-fenestrane (42) using the photoreaction of (43) as a key step. Park... 

The formation of the benzyl radical by photolysis of toluene in benzene at 4.2 and 77 K has been investigated as a function of light intensity and shown to be unimolecular and biphotonic, and to occur via the lowest excited triplet state. The gas-phase photodissociation of [2,2]paracyclophane (71) into two molecules of /7-quinodimethane and analogous dissociations of two methyl-substituted derivatives have been shown to be efficient two-photon processes.A hot molecule formed by internal conversion from the initially formed singlet electronic excited state is proposed as an intermediate, a mechanism which is completely different from that of the two-photon dissociation of (71) in low-temperature matrices, which involves a triplet state. The photolyses of [2,2]para-cylcophane and [2,2]paracyclophane-l-ene have also been studied in THF and hexane matrices at 77 K, using detection by both luminescence and absorption spectroscopy. The products from both these compounds in THF matrices included alkyl derivatives of rra/15-stilbene, and in hexane matrices alkylphenan-threnes. Cycloreversion of so-called cyclodimers of naphthalene derivatives with benzene or furan, e.g. (72), occurs efficiently upon UV irradiation. ... 

Other papers of interest in connection with azetidines include further details of the photochemical formation of azetidine derivatives from 2-cyanopyrroline N-oxide, syntheses of 2- and 3-pyridylazetidines (as nicotine analogues), the photochemical addition of the isoxazoline (7) to benzene, furan, and thiophen, and several examples of [3 + 1] addition of isocyanides to azomethine ylides. ... 

The oxidation of a ( )-flavanone with Tl(ni) nitrate, Pb tetracetate, phenyliodonium diacetate (PIDA), or [hydroxyl(tosyloxy)iodo]benzene in trimethyl orthofonnate affords the corresponding ( )-2,3-dihydrobenzo[h]furan derivative as a major product. The structures, including the relative stereochemistry, and a plausible mechanism of formation are reported. The preferred formation of a flavone from the ( )-flavanone by PIDA is explained by quantum-chemical calculations on the intermediate formed by the addition of this reagent to the enol ether derivative of the ( )-flavanone." Formation of mixed anhydrides by rapid oxidation of aldehydes, activated by pivalic acid, Bu OCl in presence of pyridine and MeCN is catalysed by TEMPO (2,2,6,6-tetramethylpiperidin-l-oxyl). The anhydrides can be converted in situ to esters, secondary, tertiary or Weinreb amides in high yield. Oxidation of the aldehyde to 2-propyl esters is also possible using only catalytic amounts of pivalic acid." ... 

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