A series of suitably functionalized C-linked carbohydrate derivatives 9-13 were prepared in good yields from alkenyl glycosides 1-4 by cross-metathesis reaction using Grubbs' catalyst [Cl2(PCy3)2Ru=CHPh]. The reaction was also applied to 6-O-allyl ether 5 and N-Cbz allylamine 6. C-Linked glycopeptide homologue 15 was prepared in 65% yield by cross-metathesis of perbenzylated β-C-allyl mannopyranoside 1 and allyl glycine derivative 8. Finally, amine-ending C-glycoside 11 was subjected to a sequence of deprotection, amidation with p-iodobenzoic acid (EDC, HOBt, DIPEA, r.t., 12 h), Sonogashira reaction [Pd(PPh3)2Cl2, Et3N, 65 °C, 6 h] and treatment with dicobalt octacarbonyl (60 °C, 6 h) to provide a `molecular asterisk' 21 in 53% yield.
使用格拉布斯催化剂[Cl2(PCy3)2Ru=CHPh],通过交叉甲基化反应从烯基糖苷 1-4 制备了一系列适当官能化的 C 链
碳水化合物衍
生物 9-13,收率良好。该反应也适用于 6-O
烯丙基醚 5 和 N-Cbz
烯丙基胺 6。通过过苄基化的δ-C-烯丙基
吡喃
甘露糖苷 1 和烯丙基甘
氨酸衍
生物 8 的交叉甲基化反应,制备出 C 联糖肽同系物 15,收率为 65%。最后,
氨基末端的 C-糖苷 11 经过去保护、对
碘苯甲酸酰胺化(EDC、
HOBt、DI
PEA,12 小时后)、Sonogashira 反应[Pd(PPh3)2Cl2、Et3N,65 °C,6 小时]和八羰基二
钴处理(60 °C,6 小时)等一系列过程,得到 "分子星号 "21,收率为 53%。