首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
2.
3.
4.
5.
6.
7.
8.
Di‐ and trisaccharide thioglycoside building blocks, ethyl (2,3,4‐tri‐O‐benzyl‐β‐d‐xylopyranosyl)‐(1→2)‐3‐O‐allyl‐4,6‐di‐O‐benzyl‐1‐thio‐α‐d‐mannopyranoside, ethyl (2,3,4‐tri‐O‐benzyl‐β‐d‐xylopyranosyl)‐(1→2)‐6‐O‐acetyl‐3‐O‐allyl‐4‐O‐benzyl‐1‐thio‐α‐d‐mannopyranoside and ethyl (2,3,4‐tri‐O‐benzyl‐β‐d‐xylopyranosyl)‐(1→4)‐[(2,3,4‐tri‐O‐benzyl‐β‐d‐xylopyranosyl)‐(1→2)]‐3‐O‐allyl‐6‐O‐benzyl‐1‐thio‐α‐d‐mannopyranoside, corresponding to repetitive structures in the capsular polysaccharide (CPS) of Cryptococcus neoformans have been synthesised using silver triflate‐promoted couplings between benzobromoxylose and properly protected mannose ethyl thioglycosides. The blocks contain an orthogonal allyl group in the 3‐position of the mannose residue to allow continued formation of the (1→3)‐linked mannan backbone of the CPS. They have benzyl ethers as persistent protecting groups to facilitate access to the acetylated target structures. Assembly of the blocks employing DMTST as promoter in diethyl ether afforded in high yield and complete stereoselectivity penta‐ and hexasaccharide motifs from C. neoformans serotype A–C. The latter were deallylated into new acceptors to allow synthesis of larger CPS‐fragments.  相似文献   

9.
10.
11.
12.
13.
14.
A new synthetic route for α-agarofuran(1b) is described. Several agarofuran derivatives were synthesized in similar way. Derivative 1d was also synthesized in a novel way, in which the substitution at C-4 was performed quantitatively. An ideal condition for cyclization of diol 7 to agarofuran (1) was found.  相似文献   

15.
The nomenclature and the synthesis of hetarylcyanamides and their reactions that take place at the cyanoamino group are discussed.  相似文献   

16.
17.
18.
19.
20.
The nature of reductive ring-opening of epoxide has been widely studied. But epoxides of agarofurans with rigid skeleton have their own specificity. Agarofurans have been found to be active on the nervous system in our institute. Reduction of epoxides may afford different types of agarofurans. This prompted us to investigate the reaction.Epoxides 1, 2, 3 were prepared by oxidation of their corresponding olefins1. Generally, the nature of the reduction of epoxides with LAH depends on the ster…  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号