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101.
102.
A new stereoselective synthesis of D-ribose (14) starting from L-glutamic acid (1) is described, by making use of the chiral center of 1 as that at C-4 of 14. Oxidation of methyl 5-O-benzyl-2,3-dideoxy-D-pent-2-enofuranoside (10) with potassium permanganate or osmium tetroxide was shown to occur preferentially from the rear side of the OMe group at C-1. 相似文献
103.
Yoshiaki Hamada Kazuko Hashiguchi Masamichi Tsuboi Yoshinori Koga Shigeo Kondo 《Journal of Molecular Spectroscopy》1984,105(1):70-80
Methyleneimine was detected in the gas phase by a moderately high resolution infrared spectrometer as one of the intermediate species produced by a pyrolysis of amines. Observed vibrational frequencies of some isotopic derivatives have been combined with the ab initio values to reach a most reliable force constants set. Some other spectroscopic parameters, involving geometrical parameters and dipole moment derivatives, have also been calculated ab initio and compared with the observation. Its half-life in our experimental apparatus was about 10 min, which is much longer than the previously reported values, 0.1 or 10 sec. 相似文献
104.
To deal with the radiation from an axially symmetric pillbox resonator embedded in LiNbO3 substrate, an eigenvalue equation is derived from the expression of the finite-element beam propagation method in a cylindrical coordinate system. By solving the eigenvalue equation iteratively, the field distributions and the angular phase constants of the pillbox resonator are evaluated. The iterative scheme of solving the eigenvalue equation is an extension of our previous direct solution method which was described for a lossless case. The results obtained by this method are compared with those obtained analytically, and excellent agreement is found. 相似文献
105.
106.
107.
108.
(±)-Isostegane isomerized into (+-)-isopicrostegane, (±)-picrostegane, and (±)-stegane, the parent compound o steganacin-type dibenzocyclooctadiene lignan lactones. 相似文献
109.
110.
Treatment of 6-amino-5-arylazo-1,3-dimethyluracils with ethyl propiolate gave the corresponding Michael-type adducts, 5-arylazo-1,3-dimethyl-6-ethoxycarbonylvinylaminouracils, which on treatment with a mixture of hydrochloric acid and acetic acid caused the acid-catalyzed rearrangement accompanied with rearrangement to give rise to the corresponding 8-anilinomethyltheophylline derivatives. In the case that the arylazo group possesses an electron-releasing substituent such as methoxy, the reaction proceeded in a different way to afford 1,2-bis(theophyllin-8-yl)ethane. The presumable reaction mechanisms for the above purine syntheses were proposed. 相似文献