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应用四步合成反应证实,在Haworth的吡喃糖甙透视结构中与C_6-侧链处于反位的2,3-内醚环可以在碱性试剂作用下转化为相应的3,6-内醚糖甙,为Ohle所提出的推论提供确切的实验证据。四步反应包括由2,3-二-O-对甲苯磺酰基-D-葡萄糖一α-甲基呲喃甙(ⅩⅢ),经三苯甲基化,得糖浆状的2,3-二-O-对甲苯磺酰基-6-O-三苯甲基-D-葡萄糖-α-甲基吡喃甙(ⅪⅤ)。然后应用Purdie-Irvine的方法进行甲基化,得结晶的2,3- 二-O-对甲苯磺酰基-4-O-甲基-6-O-三苯甲基-D-葡萄糖-α-甲基吡喃甙(ⅩⅤ);在乙酸酐中以乙酰溴置换ⅩⅤ的三苯甲基,生成糖浆状的2,3-二-O-对甲苯磺酰基-4-O-甲基-6-O-乙酰基-D-葡萄糖-α-甲基吡喃甙(ⅩⅥ)。再直接在氯仿中在0°用甲醇钠处理,得到两种结晶产物;其一为水溶性的2,3-内醚-4-甲基-D-阿罗糖-α-甲基吡喃甙(ⅪⅩ),另一为溶于有机溶剂中的2,3-二-O-对甲苯磺酰基-4-O-甲基-D-葡萄糖-α-甲基吡喃甙(ⅩⅦ)。两者的结构均经彻底甲基化为已知的结晶的2,3-内醚-4,6-二-O-甲基-D-阿罗糖-α-甲基吡喃甙(ⅩⅪ)和2,3-二-O-对甲苯磺酰基-4,6-二-O-甲基-D-葡萄糖-α-甲基吡喃甙(ⅩⅧ),加以确定。将2,3-内醚-4-O-甲基-D-阿罗糖-α-甲基吡喃甙(ⅪⅩ)在1N氢氧化钠溶液中处理得到54％产率的3,6-内醚-4-O-甲基-D-葡萄糖-α-甲基吡喃甙(ⅩⅩ),与Haworth,Owen和Smith由3,6-内醚-D-葡萄糖-α一甲基吡喃甙经部分甲基化而得的产物相同。对吡喃糖甙中的2,3-内醚环转化为3,6-内醚环体系进行了简单的构象分析。
Using the four-step synthetic reaction, it was confirmed that the 2,3-endocyclic ether ring in the transversal position of the C_6-side chain in Haworth’s pyranoside structure can be converted to the corresponding 3,6-lactone under the action of a basic reagent Glycosides provide the exact experimental evidence for Ohle’s inference. The four-step reaction consists of the reaction of 2,3-di-O-p-toluenesulfonyl-D-glucose-α-methylbenzofuranoside (XIII), tritylation to give syrup 2,3- O-p-toluenesulfonyl-6-O-trityl-D-glucose-α-methylpyranoside (XIV). Methylation was then performed using the Purdie-Irvine method to yield the crystalline 2,3-di-O-p-toluenesulfonyl-4-O-methyl-6-O-trityl-D-glucose- Methylpyranoside (XV); displacement of the trityl group of XV with acetyl bromide in acetic anhydride to produce syrupy 2,3-di-O-p-toluenesulfonyl-4-O-methyl-6- O-acetyl-D-glucose-α-methylpyranoside (XVI). Then directly treated with sodium methoxide in chloroform at 0 ° to give two crystalline products; one of them is water-soluble 2,3-endo-4-methyl-D-aloose-α-methylpyranoside (XIX) and the other is 2,3-di-O-p-toluenesulfonyl-4-O-methyl-D-glucose-α-methylpyranoside (XVII) dissolved in an organic solvent. Both structures are thoroughly methylated to the known crystalline 2,3-inner ether-4,6-di-O-methyl-D-alose-alpha-methylpyranoside (XXI) And 2,3-di-O-p-toluenesulfonyl-4,6-di-O-methyl-D-glucose-α-methylpyranoside (XVIII). Treatment of 2,3-endo-4-O-methyl-D-alose-α-methylpyranoside (XIX) in 1N sodium hydroxide solution gave 3,6-endo Ether-4-O-methyl-D-gluco-α-methylpyranoside (XX) with Haworth, Owen and Smith from 3,6-endo-D-glucose-α-methylpyranoside Partially methylated product obtained the same. A simple conformational analysis was performed on the conversion of the 2,3-endocyclic ether ring of pyranoside to the 3,6-endocyclic ring system.