据报道,由3,4,6-三-O-苄基-d-葡糖醛4立体合成了两个多羟基吡咯烷的非对映异构体,涉及裂解-再循环策略。半缩醛7从己烯糖得到4上LiAlH,在还原4,得到二醇8。选择性乙酰化8至11,然后Mitsunobu环化产生了多种保护的聚羟基吡咯烷12。氧化11和随后的立体选择性还原导致20中,C-5差向异构体的11,其在光延环化,得到polyhydroxypyrrolidine21。使用在MeOH中的Na 2 CO 3对12和21的乙酰基进行选择性脱保护。与过量的Mg的MeOH一起加热时,聚羟基吡咯烷12和21同时进行N-脱甲苯基化和脱乙酰化,以定量收率分别得到氨基醇15和24。15和24的催化氢化分别定量地提供了多羟基吡咯烷2和3。
据报道,由3,4,6-三-O-苄基-d-葡糖醛4立体合成了两个多羟基吡咯烷的非对映异构体,涉及裂解-再循环策略。半缩醛7从己烯糖得到4上LiAlH,在还原4,得到二醇8。选择性乙酰化8至11,然后Mitsunobu环化产生了多种保护的聚羟基吡咯烷12。氧化11和随后的立体选择性还原导致20中,C-5差向异构体的11,其在光延环化,得到polyhydroxypyrrolidine21。使用在MeOH中的Na 2 CO 3对12和21的乙酰基进行选择性脱保护。与过量的Mg的MeOH一起加热时,聚羟基吡咯烷12和21同时进行N-脱甲苯基化和脱乙酰化,以定量收率分别得到氨基醇15和24。15和24的催化氢化分别定量地提供了多羟基吡咯烷2和3。
A Glycal Approach to the Synthesis of Steviamine Analogues
作者:Venkatesan Santhanam、Namakkal G. Ramesh
DOI:10.1002/ejoc.201402943
日期:2014.11
The synthesis of two new stereoisomers of steviamine, namely 1,8a-di-epi-(+)-steviamine and 2,3-di-epi-(–)-steviamine, is reported, starting from tri-O-benzyl-D-glucal. The key step in the synthesis was a modified Julia olefination of a 2-formyl-polyhydroxy-pyrrolidine with a sulfone derived from ethyl acetoacetate. Glycosidase-inhibition studies revealed that 2,3-di-epi-(–)-steviamine is a selective
据报道,从三-O-苄基-D开始合成两种新的甜菊胺立体异构体,即1,8a-二-表-(+)-甜菊胺和2,3-二-表-(-)-甜菊胺-葡萄糖。合成中的关键步骤是 2-甲酰基-多羟基-吡咯烷与来自乙酰乙酸乙酯的砜的改性 Julia 烯化。糖苷酶抑制研究表明,2,3-di-epi-(-)-steviamine 是 α-半乳糖苷酶的选择性抑制剂。
A new and short synthesis of naturally occurring 1-deoxy-l-gulonojirimycin from tri-O-benzyl-d-glucal
作者:Muthupandian Ganesan、Namakkal G. Ramesh
DOI:10.1016/j.tetlet.2010.08.049
日期:2010.10
A new and short synthesis of naturallyoccurring 1-deoxy-l-gulonojirimycin from tri-O-benzyl-d-glucal, via a regioselective intramolecular cyclization of an amino triol intermediate, is described. Its absolute configuration was deduced from the single crystal X-ray analysis of compound 11.
A glycal approach towards an efficient and stereodivergent synthesis of polyhydroxypyrrolidines
作者:Vipin Kumar、Namakkal G. Ramesh
DOI:10.1016/j.tet.2005.11.037
日期:2006.2
A stereo-defined synthesis of two diastereomers of polyhydroxypyrrolidines from 3,4,6-tri-O-benzyl-d-glucal 4 involving a cleavage–recyclization strategy is reported. Hemiacetal 7 obtained from glucal 4, upon reduction with LiAlH4 afforded diol 8. Selective acetylation of 8 to 11, followed by Mitsunobu cyclization yielded the diversely protected polyhydroxypyrrolidine 12. Oxidation of 11 and subsequent
据报道,由3,4,6-三-O-苄基-d-葡糖醛4立体合成了两个多羟基吡咯烷的非对映异构体,涉及裂解-再循环策略。半缩醛7从己烯糖得到4上LiAlH,在还原4,得到二醇8。选择性乙酰化8至11,然后Mitsunobu环化产生了多种保护的聚羟基吡咯烷12。氧化11和随后的立体选择性还原导致20中,C-5差向异构体的11,其在光延环化,得到polyhydroxypyrrolidine21。使用在MeOH中的Na 2 CO 3对12和21的乙酰基进行选择性脱保护。与过量的Mg的MeOH一起加热时,聚羟基吡咯烷12和21同时进行N-脱甲苯基化和脱乙酰化,以定量收率分别得到氨基醇15和24。15和24的催化氢化分别定量地提供了多羟基吡咯烷2和3。