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81.
A highly efficient, two-step sequence method for the deoxygenation of hydroxyl groups has been developed. The method involves the preparation of the 2-(2-iodophenyl)ethyl methyl phosphite derivative of an alcohol using methyl dichlorophosphite and 2-(2-iodophenyl)ethanol. Treatment of the phosphite intermediate with (n-Bu)3SnH/AIBN in refluxing benzene cleanly produces the deoxygenation product of the original alcohol. 相似文献
82.
Shirokawa S Kamiyama M Nakamura T Okada M Nakazaki A Hosokawa S Kobayashi S 《Journal of the American Chemical Society》2004,126(42):13604-13605
A highly regio- and diastereoselective TiCl4-mediated vinylogous Mukaiyama aldol reaction using the chiral vinylketene silyl N,O-acetal has been developed. The present vinylogous Mukaiyama aldol reaction provides a unique and effective means of controlling remote asymmetric induction. The methyl group at the alpha-position is important in achieving a high level of stereoselectivity. From a synthetic point of view, this methodology can provide a one-step construction of delta-hydroxy-alpha,gamma-dimethyl-alpha,beta-unsaturated carbonyl unit that is seen in many natural polyketide products. 相似文献
83.
Ohashi M Matsubara K Iizuka T Suzuki H 《Angewandte Chemie (International ed. in English)》2003,42(8):937-940
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86.
Let D be a complex of non-trivial p-subgroups of a finite groupG, closed under G-conjugation. In this paper, a p-local geometryp(G; D) is introduced for G associated with the complex D. Thehomotopy equivalence between p(G; D) and D is also studied.2000 Mathematics Subject Classification 20E15, 51E24. 相似文献
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88.
We demonstrate the nanosecond time-gated spectroscopy of plume luminescence in UV laser ablation of human hair. Clear and sharp peaks of calcium ion (Ca+) appear in the spectrum although the Ca content is only 0.1% in human hair. Highly sensitive detection of Ca is thus possible. In the experiment, the peak intensity of Ca+ was measured for human hair samples of female subjects over a wide range of age, and compared to the bone mineral density of the lumbar vertebrae of the subjects themselves. Our experimental results suggest that this specific spectroscopy has the potential for novel diagnoses including monitoring of daily Ca intake and a screening diagnosis of osteoporosis. The spectroscopic system and time transition of plume-luminescence spectra are also described. 相似文献
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90.
Masato Tsujii 《Inventiones Mathematicae》2001,143(2):349-373
We prove the existence of absolutely continuous invariant measures for arbitrary expanding piecewise linear maps on bounded
polyhedral domains in Euclidean spaces ℝ
d
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Oblatum 6-V-1999 & 8-VI-2000?Published online: 11 October 2000 相似文献