when the intermediate 2,3,4,6-tetra-O-toluene-p-sulphonyl-D-glucitol (6) is converted into its 0–5 oxyanion. Benzyloxy participation has been exploited in a new synthesis of 2,3,5-tri-O-benzyl-α(and β)-D-ribofuranosylethyne, (20) and (4), from 2,3,4,5-tetra-O-benzyl-aldehydo-D-ribose. A synthesis of 2-α-D-ribofuranosylmaleimide, the α-isomer of showdomycin, from (20) is described.
2,3,4,6-四- ö苄基d -glucitol(5)反应以
甲苯p -磺酰基
氯在
吡啶中于60℃,以形成主要是
呋喃产物2,3,6-三ö -苄基-1,4-脱
水-
D-葡萄糖醇(10)及其5-
甲苯-对
磺酸酯(11),但失去4- O-苄基。该
吡喃产物四ö苄基1,5-脱
水- d -glucitol preponderates当中间2,3,4,6-四ö -toluene- p -sulphonyl- d -glucitol(6)转化成其0–5
氧阴离子。在新合成的2,3,5-tri- O中已经利用了苄氧基的参与苄基α(及β) - d -ribofuranosylethyne,(20)和(4),从2,3,4,5-四ö苄基醛基- d -
核糖。描述了由(20)合成2-α- D-
呋喃呋喃糖基马来
酰亚胺(Showdomycin的α-异构体)。