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41.
Hsi WC Kunde GJ Pochodzalla J Lynch WG Tsang MB Begemann-Blaich ML Bowman DR Charity RJ Cosmo F Ferrero A Gelbke CK Glasmacher T Hofmann T Imme G Iori I Hubele J Kempter J Kreutz P Kunze WD Lindenstruth V Lisa MA Lynen U Mang M Moroni A Müller WF Neumann M Ocker B Ogilvie CA Peaslee GF Raciti G Rosenberger F Sann H Scardaoni R Schüttauf A Schwarz C Seidel W Serfling V Sobotka LG Stuttge L Tomasevic S Trautmann W Tucholski A Williams C Wörner A Zwieglinski B 《Physical review letters》1994,73(25):3367-3370
42.
Evidence for demethylation of syringyl moieties in archaeological wood using pyrolysis-gas chromatography/mass spectrometry 总被引:1,自引:0,他引:1
van Bergen PF Poole I Ogilvie TM Caple C Evershed RP 《Rapid communications in mass spectrometry : RCM》2000,14(2):71-79
Archaeological oak (Quercus sp.) wood samples, ranging from 16(th) C. AD to 6000 BP, were studied using flash pyrolysis-gas chromatography/mass spectrometry to obtain insight into angiosperm lignin degradation. The pyrolysates revealed evidence of a number of 3-methoxy-1,2-benzenediol derivatives, methoxycatechols, directly related to 2,6-dimethoxyphenol, syringyl, moieties which are characteristic building blocks of angiosperm lignin. Mass spectra and mass chromatograms of these compounds are reported. The finding of these characteristic pyrolysis products in well-preserved archaeological wood provides unequivocal evidence that demethylation of syringyl units occurs very early in wood degradation. It is highly likely that the absence of abundant 3-methoxy-1, 2-benzenediols in degrading plant materials containing angiosperm lignin relates to the lability of these newly formed moieties. 相似文献
43.
Y Guindon F Soucy C Yoakim W W Ogilvie L Plamondon 《The Journal of organic chemistry》2001,66(26):8992-8996
The work described herein considers the impact of stereoelectronic effects and allylic 1,3-strain in controlling the cyclofunctionalization reaction when a hydroxyl group is at the allylic position. The stereoelectronic arguments are supported by independent iodocyclization reactions performed using two secondary alcohols. The transition-state pathways involved in these reactions are established through a comparison of relative reaction rates. A bi-directional approach is used to demonstrate the potential of the iodocyclization reaction to differentiate a terminus in molecules with a pseudo C(2) axis of symmetry, showing that two-directional synthesis can be used to differentiate between alternative transition-state pathways. 相似文献
44.
Kelvin K. Ogilvie Gholam H. Hakimelahi Zbigniew A. Proba Danny P.C. McGee 《Tetrahedron letters》1982,23(19):1997-2000
Procedure have been developed which allow for the selective derivatization of arabinonucleosides at the 5′? or 2′? and 5′? or 3′? and 5′? positions. 相似文献
45.
J.F. Ogilvie 《Journal of Molecular Structure》1976,31(2):407-410
New structural parameters have been deduced for the ground electronic states for formyl and hydroperoxyl radicals and nitrosyl hydride, from experimental rotational constants. The values obtained are consistent with known vibrational data and bond dissociation energies. 相似文献
46.
47.
The synthesis of compounds having a phosphite bridge between nucleoside units, their characteristics toward phosphodiesterases, their conversion to normal nucleotides and their use in oligonucleotide synthesis is described. 相似文献
48.
James R. Hitchin Niall M. Hamilton Allan M. Jordan Amanda J. Lyons Donald J. Ogilvie 《Tetrahedron letters》2012,53(23):2868-2872
A novel scalable stereoselective synthesis of 3α- and 3β-amino-5α-androstan-17-ones and 3α- and 3β-amino-5α-pregnan-20-ones has been developed using phthalimide based Mitsunobu chemistry. In all four cases, the products were isolated as single diastereoisomers in high chemical yield and purity without the need for chromatography at any stage in their syntheses. 相似文献
49.
Theoretical expressions for the Herman-Wallis factors in terms of the Dunham potential-energy parameters and dipole-moment coefficients were derived for higher overtone bands by the method of computer algebra. These results were applied to an analysis of the vibration-rotational intensities of HCl, leading to a good fit of the data and a dipole-moment function that is improved and extended by comparison with previous results. 相似文献
50.
Whitehouse CJ Yang W Yorke JA Tufton HG Ogilvie LC Bell SG Zhou W Bartlam M Rao Z Wong LL 《Dalton transactions (Cambridge, England : 2003)》2011,40(40):10383-10396
The substrate-free crystal structure of a five-mutation directed evolution variant of CYP102A1 (P450(BM3)) with generic activity-enhancing properties ("KT2") has been determined to 1.9-? resolution. There is a close resemblance to substrate-bound structures of the wild-type enzyme (WT). The disruption of two salt bridges that link the G- and I-helices in WT causes conformational changes that break several hydrogen bonds and reduce the angle of the kink in the I-helix where dioxygen activation is thought to take place. The side-chain of a key active site residue, Phe87, is rotated in one molecule of the asymmetric unit, and the side-chains of Phe158 and Phe261 cascade into the orientations found in fatty-acid-bound forms of the enzyme. The iron is out of the porphyrin plane, towards the proximal cysteine. Unusually, the axial water ligand to the haem iron is not hydrogen-bonded to Ala264. The first electron transfer from the reductase domain to the haem domain of substrate-free KT2 is almost as fast as in palmitate-bound WT even though the reduction potential of the haem domain is only slightly more oxidising than that of substrate-free WT. However, NADPH is turned over slowly in the absence of substrate, so the catalytic cycle is gated by a step subsequent to the first electron transfer-a contrast to WT. Propylbenzene binding slightly raises the first electron transfer rate in WT but not in KT2. It is proposed that the generic rate accelerating properties of KT2 arise from the substrate-free form being in a catalytically ready conformation, such that substrate-induced changes to the structure play a less significant role in promoting the first electron transfer than in WT. 相似文献