(-)-亚奎宁酸具有八种可能的立体异构体,它们既可以天然存在,也可以作为热食品加工的产物出现。在这方面的贡献,我们已经合成了选择性四种异构体,即,外延-quinic酸,粘膜-quinic酸,顺-quinic酸和鲨-quinic酸,开发一个串联LC-MS方法确定所有的立体异构奎尼酸。通过单晶X射线晶体学已明确表征了四种衍生物。通过使用乙酸/浓H 2 SO 4对(-)-奎宁酸进行非选择性异构化,可获得缺少的奎宁酸非对映异构体允许进行色谱分离和奎宁酸的所有非对映异构体分配。我们首次报告,根据其串联质谱碎片质谱图及其洗脱顺序,可以可靠地区分一整套立体异构体。提出了特征性碎片机制的原理。在这项研究中,我们还观察到粘膜-quinic酸,鲨-quinic酸和外延-quinic酸存在于水解危地马拉焙炒咖啡样品焙烧可能的产品。
(-)-亚奎宁酸具有八种可能的立体异构体,它们既可以天然存在,也可以作为热食品加工的产物出现。在这方面的贡献,我们已经合成了选择性四种异构体,即,外延-quinic酸,粘膜-quinic酸,顺-quinic酸和鲨-quinic酸,开发一个串联LC-MS方法确定所有的立体异构奎尼酸。通过单晶X射线晶体学已明确表征了四种衍生物。通过使用乙酸/浓H 2 SO 4对(-)-奎宁酸进行非选择性异构化,可获得缺少的奎宁酸非对映异构体允许进行色谱分离和奎宁酸的所有非对映异构体分配。我们首次报告,根据其串联质谱碎片质谱图及其洗脱顺序,可以可靠地区分一整套立体异构体。提出了特征性碎片机制的原理。在这项研究中,我们还观察到粘膜-quinic酸,鲨-quinic酸和外延-quinic酸存在于水解危地马拉焙炒咖啡样品焙烧可能的产品。
Novel and Efficient Syntheses of (−)-Methyl 4-<i>e</i><i>pi</i>-Shikimate and 4,5-Epoxy-Quinic and -Shikimic Acid Derivatives as Key Precursors to Prepare New Analogues
We have developed simple methods that provide a rapid entry into the synthesis of a series of quinate and shikimate analogues, including (−)-methyl 4-epi-shikimate and the 4,5-epoxy analogues of the parent acids. Epoxy derivatives of quinic and shikimic acids were converted into methyl scyllo-quinate and (+)-methyl 3-epi-shikimate, respectively, by processes involving a regio- and stereoselective epoxide
We have synthesized several isomers of 19-nor-vitamin D analogues possessing a hydroxy group at C-2 as well as novel derivatives bearing an epoxy substituent at the A-ring. All vitamins were prepared in convergent syntheses utilizing the modified Julia olefination. 1α,2α,25-Trihydroxy-19-nor-vitamin D3 (3) and 2β,3β-epoxy-1α,25-dihydroxy-3-deoxy-19-nor-vitamin D3 (10), which showed the highest affinity