Divergent Synthesis of 4-<i>epi</i>-Fagomine, 3,4-Dihydroxypipecolic Acid, and a Dihydroxyindolizidine and Their β-Galactosidase Inhibitory and Immunomodulatory Activities
作者:K. S. Ajish Kumar、J. S. Rathee、M. Subramanian、S. Chattopadhyay
DOI:10.1021/jo400448p
日期:2013.8.2
A divergent asymmetric synthesis of the titled iminosugars has been formulated starting from a chiral homoallyl alcohol as the versatile intermediate. The homoallyl alcohol was prepared by a highly diastereoselective Barbier reaction on a d-glucose-derived aldehyde. The protection of its hydroxyl function followed by reductive ozonolysis of the olefin and a subsequent one-pot three-step protocol involving
以手性均烯丙基醇为通用中间体,已配制了标题亚氨基糖的不同不对称合成物。通过在衍生自d-葡萄糖的醛上的高度非对映选择性的Barbier反应来制备均烯丙基醇。保护其羟基官能团,然后进行烯烃的还原性臭氧分解,以及随后的一锅三步操作(包括施陶丁格反应,还原胺化和苄氧基羰基保护),产生了重要的双环呋喃并哌啶衍生物。通过以下标准反应将其转化为目标化合物。在合成的化合物中,4- epi- fagomine(2b)是最好的β-半乳糖苷酶抑制剂,并且还阻止了LPS介导的Raw 264.7巨噬细胞活化。它的同类物3,4-二羟基哌酸(4b)在低浓度(10μM)时也显示出相似的细胞因子和酶抑制特性趋势,但在较高浓度时具有促炎作用。双环化合物二羟基吲哚并吡啶(21)降低了LPS激活的Raw 264.7细胞中促炎细胞因子(IL-1β和TNF-α)的水平,而未显示任何酶抑制活性。