C-glycoside synthesis II: Henry condensations of 4,6-O-alkylidene pyranoses with a 1,3-proton transfer catalyst- a route to blocked aminomethyl-C-glycosides.
作者:Kenneth N. Drew、Paul H. Gross
DOI:10.1016/s0040-4020(01)86545-5
日期:1991.8
prepared form of elemental iron in aqueous tetrahydrofuran under CO2 to aminomethyl-C-glycopyranoside (16), characterized as N-acetyl, peracetyl, and N-Cbz derivatives (7, 8, 9, 10), and converted with diazonium salt to a triazene derivative (II). Nitroalkenes are only mechanistic intermediates in our condensations with nitromethane, but they undergo Michael additions with a second mole of nitromethane
在新型的1,3-质子转移催化剂(2-羟基吡啶(2-HP)/ 1,8-二氮杂双环[5.4.0]十一碳-7-烯(DBU)/分子筛)的存在下,4,6- O-亚苄基-D-吡喃葡萄糖(1),4,6 - O-异亚丙基-D-甘露糖(12)和4,6 - O-异亚丙基-D-葡萄糖(16)与硝基甲烷在THF中进行亨利缩合反应,得到乙缩醛保护的硝基甲基C-糖吡喃糖苷(分别为2、13和17),其特征是其O-乙酰基衍生物(分别为5、15和18)。从4,6-O-亚苄基Dglucopyranose亨利产物可以减少,与4,6-保留ö CO下-亚苄基保护基团,通过在含水四氢呋喃元素铁的特制形式2生成氨基甲基-C-糖吡喃糖苷(16),其特征为N-乙酰基,过乙酰基和N-Cbz衍生物(7、8、9、10),并与重氮盐转化为三氮烯衍生物(II)。硝基烯烃只是我们与硝基甲烷缩合反应中的机械中间体,但它们会与第二摩尔硝基甲烷进行迈克尔加成反应,生成新颖的5