Reductive cleavage of glycosides
Reductive cleavage of glycosides
复制标题
糖苷的还原裂解
DOI：
10.1021/ja00376a065
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发表时间：
1982
影响因子：
15
通讯作者：
G. Gray
中科院分区：
文献类型：
--
作者：
D. Rolf;G. Gray
(13)2a:NMR(D20)5 3.39、3.49、3.62(三个、9H、甲氧基)、3.17-3.79(络合物、7H、H-1a、2、3、4、5、6)、4.19(dd、J=4.7、11.5Hz、1H， H-le);[a] 25D+ 51 (c 2.0, H2G)[点燃。 10[a]25D+53.8).(14)将化合物1、三乙基硅烷、三氟化硼乙醚合物和三氟乙酸以已经给出的比例混合，9并将混合物冷却至0℃，然后滴加乙酸酐(12当量)。升温至室温后，得到均匀溶液。在室温下保持24小时后，将反应混合物用CHCl 3 稀释，用冷的NaHCO 3 水溶液萃取，经无水Na 2 SG 4 干燥，并蒸发至干，得到2b，收率81％：NMR(CDCl 3 ) 2.11(s，3H，乙酰氧基)，3.36，3.48，3.53(3s，9H，甲氧基)， 3.11-3.67（复数，6 H、H-1a、2、3、5、6）、4.12（dd、J= 5.2、11.0 Hz、1 H、H-le）、4.82（t、J= 9.4 Hz、1 H、H-4）；[a] 25D+ 30（c 2.3、CHC13）。可以探索裂解反应，选择模型糖苷进行研究，仅产生挥发性还原产物。然而，所有检查的化合物（表I）均通过还原环状氧鎓离子中间体而产生高产率的脱水糖醇。仅在甲基 2,3,5-三-O-甲基-/SD-呋喃核苷 (6a) 的还原中观察到大量 (5%) 的无环产物。 15 o、Rb、Rc、Rd、Re、Rf、Rg、Rs、R2=QMe、R3=Me
(13) 2a: NMR (D20) 5 3.39, 3.49, 3.62 (three s, 9 H, methoxyl), 3.17-3.79 (complex, 7 H, H-la, 2, 3, 4, 5, 6), 4.19 (dd, J= 4.7, 11.5 Hz, 1 H, H-le);[a] 25D+ 51 (c 2.0, H2G)[lit. 10 [a] 25D+ 53.8).(14) Compound 1, triethylsilane, boron trifluoride etherate, and tri-fluoroacetic acid were mixed in the proportions already given, 9 and the mixture was cooled to 0 C prior to the dropwiseaddition of acetic anhydride (12 equiv). After this warmed to room temperature, a homogeneous solution was obtained. After being kept for 24 h at room temperature, the reaction mixture was diluted with CHC13, extracted with cold aqueous NaHC03, dried over anhydrous Na2SG4, and evaporated to dryness to give 2b in 81% yield: NMR (CDC13) 2.11 (s, 3 H, acetoxy), 3.36, 3.48, 3.53 (three s, 9 H, methoxyl), 3.11-3.67 (complex, 6 H, H-la, 2, 3, 5, 6), 4.12 (dd, J= 5.2, 11.0 Hz, 1 H, H-le), 4.82 (t, J= 9.4 Hz, 1 H, H-4);[a] 25D+ 30 (c 2.3, CHC13). cleavage reaction could be explored, model glycosides were chosen for study that would yield only volatile reduction products. All of the compounds examined (Table I), however, gave high yields of anhydroalditols arising from reduction of cyclic oxoniumion intermediates. Only in the reduction of methyl 2, 3, 5-tri-O-methyl-/SD-ribofuranoside (6a) was a significant amount (5%) of an acyclic product observed. 15 o, R b, R c, R d, R e, R f, R g, R s, R2= QMe, R3= Me