The structures and relative stereochemistries of rocaglamide, a novel antileukemic 1 H-cyclopenta [ b ] benzofuran isolated from Aglaia elliptifolia, and dehydrorocaglamide, derived from rocaglamide, have been established from spectral and single-crystal X-ray analysis.

The electronic properties of N-doped rutile TiO2(110) have been investigated using synchrotron-based photoemission and density-functional calculations. The doping via N2+ ion bombardment leads to the implantation of N atoms (approximately 5% saturation concentration) that coexist with O vacancies. Ti 2p core level spectra show the formation of Ti3+ and a second partially reduced Ti species with oxidation states between +4 and +3. The valence region of the TiO(2-x)N(y)(110) systems exhibits a broad peak for Ti3+ near the Fermi level and N-induced features above the O 2p valence band that shift the edge up by approximately 0.5 eV. The magnitude of this shift is consistent with the "redshift" observed in the ultraviolet spectrum of N-doped TiO2. The experimental and theoretical results show the existence of attractive interactions between the dopant and O vacancies. First, the presence of N embedded in the surface layer reduces the formation energy of O vacancies. Second, the existence of O vacancies stabilizes the N impurities with respect to N2(g) formation. When oxygen vacancies and N impurities are together there is an electron transfer from the higher energy 3d band of Ti3+ to the lower energy 2p band of the N(2-) impurities.

Scheme I 4 concomitantly, 2-methylene ketone 4g was formed (monitored by NMR). After 4 h, dehydrostannation was complete, and the precipitate was filtered off. Aqueous workup of the filtrate (pentane/aqueous NH4C1) followed by evaporation of the solvents and bulb-to-bulb distillation afforded 2-methylenecycloheptanone (4g) in 80% yield. Similarly, essentially quantitative conversion of 3 to 4 (eq 1) was observed in the reaction of 3 with Me2SO-d6/CDCl3 3 4 at 60 °C (by NMR) except for 3f which did not bear hydrogen ß to the stannyl group.9 The results are shown in Table I. The dehydrostannation of 3d,e,g,h proceeded with shorter reaction time than 3a-c. It seems that for dehydrostannation to occur, the intramolecular coordination of the carbonyl oxygen to the Sn atom (as indicated by IR) may play a key role. In fact, dehydrostannation did not take place with simple n-BuSnCl3 even under more forcing conditions (60 °C, 1 day). One plausible explanation for the present reaction is shown in Scheme I. The initial role of Me2SO may be the one as a base toward /3-hydrogen10 which may be sufficiently acidic due to the inductive effect of the adjacent carbonyl coordinated to the Sn. Thus, the deprotonation from 5 and subsequent destannylation via 6 would occur to lead to 4 and HSnCl3(Me2SO)" complex.11,12 Interestingly, the reaction of siloxycyclopropane 7 with SnCl4 in CH2C12 proceeded similarly and afforded ß-tríchlorostannyl aldehyde 8 (semisolid, vc=0 1680 cm-1). The (9) As the preparative method of /3-stannyl ketones 3, hydrostannation of ,/8-unsaturated ketones with HSnClg (in situ generated under acidic conditions: HC1 and SnCl2) has been known. The observed dehydrostannation promoted by Me2SO formally corresponds to its reverse reaction. See:

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Bioactivity-guided fractionation of the methanol extract of Goreishi (the feces of Trogopterus xanthipes Milne-Edwards) afforded one new and three known cytotoxic triterpenes, namely, 3-O-cis-p-coumaroyltormentic acid, pomolic acid, 2 alpha-hydroxyursolic acid, and jacoumaric acid. In the course of this investigation, six additional compounds having no cytotoxic activity were isolated, namely, maslinic acid, 3-O-trans-p-coumaroylmaslinic acid, ursolic acid, tormentic acid, euscaphic acid, and a new triterpene, 3-O-trans-p-coumaroyltormentic acid. The structures of the new compounds were established on the basis of X-nucleus-proton correlation with fixed evolution time (XCORFE) and other spectroscopic evidence.