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111.
Yoshinori Tominaga Milton L. Lee Raymond N. Castle 《Journal of heterocyclic chemistry》1981,18(5):977-979
The cyclization of 2-acetonylthionaphthalene, prepared from 2-mercaptonaphthalene (1) and chloro-acetone in the presence of sodium hydroxide, with polyphosphoric acid gave 1-methylnaphtho[2,1-b]thiophene (4) in 64% overall yield from 1. By bromination with N-bromosuccinimide, 4 was converted in 40% yield into l-bromomethylnaphtho[2,1-b]thiophene (8) . Treatment of 8 with potassium cyanide in a phase-transfer medium gave l-cyanomethylnaphtho[2,1-b]thiophene (10) in good yield. Compound 10 was reduced to the corresponding aldehyde 11 and then cyclized with polyphosphoric acid to phenaleno[l,9-bc]thiophene (12) in 24% overall yield from 10. 相似文献
112.
Marvin L. Tedjamulia Hirotaka Kudo Raymond N. Castle Milton L. Lee 《Journal of heterocyclic chemistry》1984,21(2):321-325
The syntheses of naphtho[1,2–6:7,6-b′]bisbenzo[b]thiophene ( 4 ), naphtho[1,2–6:7,8-b′]bisbenzo[b]thiophene ( 5 ), naphtho[2,1-b:7,6-b′]bisbenzo[b]thiophene ( 8 ), naphtho[2,1-b:7,8-b′]bisbenzo[b]thiophene ( 9 ), naphtho-[1,2–6:5,6-b′]bisbenzo[b]thiophene ( 14 ), naphtho[1,2–6:6,5-b]bisbenzo[b]thiophene ( 17 ) and naphtho[2,1–6:-6,5-b′]bisbenzo[b]thiophene ( 23 ) are reported. 相似文献
113.
114.
Philippe Vioget Massimiliano Bonivento Raymond Roulet Pierre Vogel 《Helvetica chimica acta》1984,67(6):1630-1637
The endocyclic double bond C(2), C(3) in 5,6-dimethylidene-7-oxabicyclo[2.2.1]-hept-2-ene ( 1 ) can he coordinated selectively on its exo-face before complexation of the exocyclic s-cis-butadiene moiety. Irradiation of Ru3(CO)12 or Os3(CO)12 in the presence of 1 gave tetracarbonyl [(1R,2R, 3S,4S)-2,3-η-(5,6-dimethylidene-7-oxabicyclo[2.2.1]-hept-2-ene)]ruthenium ( 6 ) or -osmium ( 8 ). Similarly, irradiation of Cr(CO)6 or W(CO)6 in the presence of 1 gave pentacarbonyl[(1R, 2R, 3S,4S)-2,3-η-(5,6-dimethylidene-7-oxabicyclo[2.2.1]hept-2-ene)]chromium (10) or -tungsten (11) . Irradiation of complexes 6 and 11 in the presence of 1 led to further CO substitution giving bed-tricarbonyl-ae-bis[(1R,2R,3S,4S)-2,3-η-(5,6-dimethylidene-7-oxabicyclo[2.2.1]hept-2-ene)]ruthenium ( 7 ) and trans-tetracarbonyl[(1R,2R,3S,4S)-2,3-η-(5,6-dimethylidene-7-oxabicyclo-[2.2.1]hept-2-ene)]tungsten (12) , respectively. The diosmacyclobutane derivative cis-m?-[(1R,3R,3S,4S)-(5,6-dimethylidene-7-oxabicyclo[2.2.1]hepta-2,3-diyl)]bis(tetracarbonyl-osmium) (Os-Os) (9) wa also obtained. The Diels-Alder reactivity of the exocyclic s-cis-butadiene moiety in complexs 7 and 8 was found to be significantly higher than that of the free triene 1 . 相似文献
115.
Raymond S. Norton 《Tetrahedron》1977,33(19):2577-2581
A method is proposed for differentiating brominated carbons from chlorinated carbons by means of natural-abundance 13C NMR spectroscopy. The basis of the method is that the spin-lattice relaxation behaviour of brominated carbons is influenced by carbon-bromine scalar interactions, which can lead to shortened 13C spin-lattice relaxation times and reduced values of the nuclear Overhauser enhancement. C-Cl scalar interactions make a negligible contribution to the spin-lattice relaxation of chlorinated carbons. These effects are illustrated by measurement of the 13C spin-lattice relaxation times and integrated intensities of chloro-, bromo and iodobenzene and chloro-, bromo- and iodocyclohexane. The method is then tested on four polyhalogenated marine natural products. The results indicate that 13C relaxation measurements can be used to distinguish brominated carbons from chlorinated carbons in the case of halogenated quaternary carbons, sp2 hydridized methine carbons and some sp3 hydridized methine carbons, but not in the case of halogenated methylene carbons or gem-dihalo substituted methine carbons. 相似文献
116.
Summary Treatment oftrans-[Mo(CNMe)2(PMe2Ph)4] andme-[W(CNMe)3(PMe2Ph)3] with sulphuric or hydrochloric acids in methanol or ethanol, or in methanol alone, under irradiation, gives methylamine, ammonia and hydrocarbons (mainly methane). The complex [W2(CNMe)4(-CNHMe)2(PMe2Ph)4]2+ cation has been obtained by the treatment ofmer-[W(CNMe)3(PMe2Ph3] with H2SO4 or [Et2OH][BF4] and gives methylamine, ammonia and methane on further acid treatment. 相似文献
117.
Lee SH Williams MV DuBois RN Blair IA 《Rapid communications in mass spectrometry : RCM》2003,17(19):2168-2176
There is an increasing need to be able to conduct quantitative lipidomics analyses as a complement to proteomics studies. The highest specificity for proteomics analysis can be obtained using methodology based on electrospray ionization (ESI) or atmospheric pressure chemical ionization (APCI) coupled with liquid chromatography/tandem mass spectrometry (LC/MS/MS). For lipidomics analysis it is often necessary to be able to separate enantiomers and regioisomers. This can be very challenging when using methodology based on conventional reversed-phase chromatography. Normal-phase chromatography using chiral columns can provide dramatic improvements in the resolution of enantiomers and regioisomers. However, conventional ESI- and APCI-MS/MS has limited sensitivity, which makes it difficult to conduct studies in cell culture systems where only trace amounts of non-esterified bioactive lipids are present. The use of electron capture APCI-MS/MS overcomes this problem. Enantiomers and regioisomers of diverse bioactive lipids can be quantified using stable isotope dilution methodology coupled with normal-phase chiral chromatography and electron capture APCI-MS/MS. This methodology has allowed a lipidomics profile from rat epithelial cells maintained in culture to be delineated and allowed the effect of a non-selective lipoxygenase inhibitor to be assessed. 相似文献
118.
Jiann-Kuan Luo Andrew S. Zektzer Raymond N. Castle 《Journal of heterocyclic chemistry》1991,28(3):737-743
The synthesis of two novel polycyclic heterocyclic ring systems via photocyclization are reported. These are benzo[f]thieno[2′,3′:4,5]thieno[2,3-c]quinoline and benzo[A]thieno-[2′,3′:4,5]thieno[2,3-c]quinoline. The total assignment of their 1H- and 13C-nmr spectra was determined by utilizing two-dimensional nmr spectroscopic methods. 相似文献
119.
PHOTOINHIBITION OF PHOTOSYNTHESIS IN NATURAL WATERS* 总被引:1,自引:0,他引:1
Raymond C. Smith Karen S. Baker Osmund Holm-Hansen Robert Olson 《Photochemistry and photobiology》1980,31(6):585-592
Abstract— A quantitative analysis of the wavelength-dependent influence of solar irradiance on natural phytoplankton photosynthesis has been made. The effect on productivity due to several different UV radiation regimes has been measured. In the course of this analysis, it has been shown that the biological weighting function for photoinhibition of chloroplasts (Jones and Kok, 1966) allows the calculation of a biologically effective dose which is consistent with the measured photoinhibition in natural phytoplankton populations. The ecological implications of a change in available UV radiation, possibly due to anthropogenic altering of the ozone layer, are explored and it is found that the present static bottle l4 C technique of measuring in situ phytoplankton productivity does not lend itself to assessing accurately the potential ecological consequences of possible increased MUV (middle ultraviolet radiation in the 280–340 nm region) on phytoplankton populations. A small change in MUV has a relatively minor effect on photoinhibition dose rates whereas it has a large potential effect on DNA dose rates. 相似文献
120.
Ali Mohammad Akbar Mirza Aminul Huq Keng See Tho Wai Butcher Raymond J. 《Transition Metal Chemistry》2003,28(2):241-245
Condensation of 2,6-diacetylpyridine (dap) with S-methyldithiocarbazate (smdtc) in a 1:2 molar ratio yields a bicondensed pentadentate Schiff base (H2dapsme) which reacts with K2MCl4 (M = PdII, PtII) giving stable complexes of empirical formula, [M(dapsme)] · 0.5Me2CO. These complexes have been characterized by a variety of physico-chemical techniques. Condensation of dap with smdtc in a 1:1 molar ratio also yields the bicondensed Schiff base (H2dapsme) as the major product, but a mono-condensed one-armed Schiff base (Hmdapsme) is also obtained as a minor product. The latter reacts with K2PdCl4 in an EtOH–H2O mixture yielding a crystalline complex of empirical formula, [Pd(mdapsme)Cl], the crystal structure of which has been determined by X-ray diffraction. The complex has a distorted square-planar structure in which the ligand is coordinated to the palladium(II) ion as a uninegatively charged tridentate chelating agent via the pyridine nitrogen atom, the azomethine nitrogen atom and the thiolate sulfur atom; the oxygen atom of the acetyl group does not participate in coordination. 相似文献