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31.
Occurrence of a new electron transfer mechanism in the LiAlH4 reduction of 9-chloromethylanthrancene, diphenylchloromethane and 9-bromofluorene is demonstrated. Alanate anion serves as a source of electrons and hydrogen atoms. 相似文献
32.
Amarendra Patra Alok K. Mitra Saroj Ghosh Amitava Ghosh A. K. Barua 《Magnetic resonance in chemistry : MRC》1981,15(4):399-400
Carbon-13 NMR signal assignment of a number of polyoxygenated triterpenes of the olean-12-ene and urs-12-ene series, carried out by considering the changes in chemical shift produced by the change of oxygenation pattern(s), and using methyl oleanolate as a model, are reported. 相似文献
33.
Amarendra Patra Apurba K. Mukhopadhyay Alok K. Mitra 《Magnetic resonance in chemistry : MRC》1981,17(3):166-168
Carbon-13 signal assignments of taraxasteryl acetate, taraxasteryl palmitate, taraxasterol and epi-friedelinyl acetate are reported. Some signal assignments of the friedelanones, reported recently by others, are inconsistent and require revision. 相似文献
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Amarendra Patra Apurba K. Mukhopadhyay Alok K. Mitra Aditi K. Acharyya 《Magnetic resonance in chemistry : MRC》1981,15(1):99-101
Some carbon-13 NMR signal assignments of diazepam, flurazepam, clonazepam and chlordiazepoxide have been revised and the assignments of nitrazepam are reported. The assignments of the various resonances were made by considering the changes in chemical shifts produced by the change of substituents and also by comparison with the chemical shifts of model compounds. 相似文献
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The new molybdenum cyanonitrosyl complexes, R2[Mo(NO)(CN)5]·2H2O (R = Ph4P and Bu4N) and [Mo(NO)(CN)3(L-L)]·H2O [L-L = 相似文献
39.
Conformational flexibility of the ammonium complex of macrocyclic 18-crown-6 at 100 K < or = T < or = 300 K is studied using a positron microprobe in conjunction with molecular dynamics simulations. The ammonium cation, encapsulated in a three-pointed hydrogen-bonding perching arrangement, undergoes unhindered facile rotation inside the crown cavity, and the ether backbone adopts itself to the dynamic cation conformation. Preferential localization of the positron in the vicinity of the encapsulated cation results in the positron sensing changes in the local electron density distribution arising from the unrestricted rotational motion of the cation as well as from the slow motion of the crown backbone and hence sensing only an average conformation of the complex. 相似文献
40.
Pregnane oligoglycoside, namely roylinine, and a pregnane derivative, namely marsgenin, have been isolated from chloroform-soluble extract of dried stem of Marsdenia roylei, and their structures were determined using 1H-NMR, 13C-NMR, 1H-1H COSY, HSQC, TOCSY and FABMS spectral techniques as well as chemical degradation and derivatisation. 相似文献