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Photooxygenation of anhydrodeoxydihydroartemisinin (4) followed by chromatographic separation of the reaction mixture yielded the new compounds alpha- (5) and beta-hydroperoxydeoxyartemisitene (8) and the formate ester 7, together with two previously reported compounds, 6 and 9. Reduction of 5 using polymer-bound triphenylphosphine afforded the new compound dihydrodeoxyartemisitene (10). Treatment of 10 with a catalytic amount of BF(3)-OEt(2) yielded the C(2)-symmetrical dimer bis(dihydrodeoxyartemisitene) ether (11) and two new compounds, dihydrodeoxyartemisitene methyl ether (12) and the dimer 13, as minor products. Dehydroacetoxylation of 5 using acetic anhydride in pyridine afforded deoxyartemisitene (14). The identities of the new compounds (5, 7, 8, 10-14) were deduced from their spectral data and by chemical derivatization. The stereochemistry of dimer 11 was defined on the basis of X-ray crystallographic analysis. All compounds were evaluated in vitro in the National Cancer Institute drug-screening program consisting of 60 human cancer cell lines derived from nine different tissues. Of the compounds tested, deoxyartemisitene (14) demonstrated significant cytotoxicity against a number of human cancer cell lines.

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The Jurassic–Early Cretaceous was a time of variable organic carbon burial associated with fluctuations of marine primary productivity, weathering intensity, and redox conditions in the pore and bottom water at paleo-shelf areas in north Egypt. This time interval characterized the deposition of, from old to young, the Bahrein, Khatatba, Masajid, and Alam El Bueib Formations in the north Western Desert. Although several studies have been devoted to the excellent source rock units, such as the Khatatba and Alam El Bueib Formations, studies on paleoenvironmental changes in redox conditions, paleoproductivity, and continental weathering and their impact on organic carbon exports and their preservation for this interval are lacking. This study presents organic and inorganic geochemical data for the Jurassic–Lower Cretaceous sediments from the Almaz-1 well in the Shushan Basin, north Western Desert. A total of 32 cuttings samples were analyzed for their major and trace elements, carbonates, and total organic carbon (TOC) contents. Data allowed the reconstruction of paleoenvironmental conditions in the southern Tethys Ocean and assessment of the changes in paleo-redox, paleo-weathering, and marine primary productivity, and the role of sediment supply. Additionally, factors that governed the accumulation of organic matter in the sediment were interpreted. Results showed that the Khatatba Formation was deposited during a phase of enhanced marine primary productivity under prevalent anoxia, which triggered enhanced organic matter production and preservation. During the deposition of the Khatatba Formation, significant terrigenous sediment supply and continental weathering were followed by a limited contribution of coarse clastic sediment fluxes due to weak continental weathering and enhanced carbonate production. The Bahrein, Masajid, and Alam El Bueib Formations were deposited during low marine primary productivity and prevalent oxygenation conditions that led to poor organic matter production and preservation, respectively. A strong terrigenous sediment supply and continental weathering predominated during the deposition of the Bahrein Formation and the lower part of the Alam El Bueib Formation compared to the limited coarse clastic supply and continental weathering during the deposition of the carbonate Masajid Formation and the upper part of the Alam El Bueib Formation. Such conditions resulted in the enhanced dilution and decomposition of labile organic matter, and, thus, organic carbon-lean accumulation in these sediments.

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