20,453 research outputs found
“Preparation of Thaliporphine and Lirioferine from Glaucine by Treatment with Hydrogen Bromide
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An Improved Oxidative Cleavage Method for Large Scale Preparation of Some Acid-Labile Aglycones from Glycosides
No full textA practical method for large-scale preparation of acid- labile aglycones including protopanaxadiol, protopanaxatriol , cycloastragenol, and jujubogenin from the corresponding glycoside containing fraction was developed. The key point of this improved method is to generate and maintain the critical reaction conditions, anhydrous and strongly basic, in situ. This effort overcomes the weakness of the reported method for oxidative cleavage of glycones and scales up the preparation of these acid -labile aglycones for further studies
Cyclopeptide Alkaloids from Stems of Paliurus Ramossisimus
No full textThree 13-membered cyclopeptide alkaloids, paliurines G, H and I, together with six known alkaloids, nummularine H, daechuine-S3, paliurines A, C, and F, were isolated from the stein of Paliurus ramossisimus by a combination of centrifugal partition chromatography and preparative TLC. Their structures were characterized and established on the basis of spectral analysis. A preliminary study indicated that nummularine H could shorten the methohexital induced sleeping time. (C) 2001 Elsevier Science Ltd. All rights reserved
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