GLYCOSYLIDENE CARBENES .2. SYNTHESIS OF O-ARYL GLYCOSIDES
GLYCOSYLIDENE CARBENES .2. SYNTHESIS OF O-ARYL GLYCOSIDES
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DOI：
10.1002/hlca.19900730621
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发表时间：
1990-01-01
影响因子：
1.8
通讯作者：
VASELLA, A
中科院分区：
文献类型：
--
作者：
BRINER, K;VASELLA, A
苯酚、4-甲氧基苯酚-4-硝基苯酚、地衣酸甲酯（1）和2，6-二（叔丁基）-4-甲基苯酚（BHT; 2）已通过热反应（20 - 60 ℃）糖基化。与各种糖基亚基衍生的二氮杂环丙烷反应。4-甲氧基苯酚与D-亚葡萄糖基衍生的二氮杂环丙烷3反应，得到O-葡萄糖苷（4和5，69%; 3：1）和C-葡萄糖苷（6和7，16%; 1：1）。类似地，苯酚产生O-葡糖苷（10和11，70%; 4：1）和C-葡糖苷（12和13，13%，1：1）。4-硝基苯酚仅得到O-糖苷14和15（75%，3：2;方案1），以及D-半乳糖基衍生的二氮杂环丙烷17至22和23（52%（来自16）），65：35;方案2）。苯酚与17的反应产生58%（从16）的O-半乳糖苷18和19（4：1）和14%的C-半乳糖苷20和21（1：1）。从D-甘露糖亚基衍生的二氮杂环丙烯25，我们主要获得α- D型26例（占24例的38%）。这些结果被解释为假设一个中间体（大概是一个glycosylidene carbene）首先去质子化的苯酚，产生一个离子对，结合起来，得到O-和-与电子丰富的酚盐-也C-糖苷。3与4-硝基苯酚和4-甲氧基苯酚的竞争实验得到了前者（14和15）和后者苯酚（4-7）几乎等量的产物。然而，OH基团的动力学酸度的差异可能形成区域选择性糖苷化的基础，如3与orsellinate甲酯（1）的反应所证明的，仅产生4-O-单糖基化产物27和28（78%，85：15），尽管二糖苷化是可能的（27 → 28）。31和32; 67%，4：3;方案3）。空间位阻不影响这种类型的糖苷化; 3与位阻BHT（2）反应得到33和34（81%，4：1）。的主要形成的1，2-反式-构型的O-芳基糖苷是合理化的邻组参与的2-苄氧基。
Phenol, 4-methoxyphenol-4-nitrophenol, methyl orsellinate (1), and 2,6-di(tert-butyl)-4-methylphenol (BHT; 2) have been glycosylated by thermal reaction (20-60.degree.) with various glycosylidene-derived diazirines. 4-Methoxyphenol reacted with the D-glucosylidene-derived diazirine 3 to give O-glucosides (4 and 5, 69%, 3:1) and C-glucosides (6 and 7, 16%; 1:1). Similarly, phenol yielded O-glucosides (10 and 11, 70%; 4:1) and C-glucosides (12 and 13, 13%, 1:1). 4-Nitrophenol gave only O-glycosides, to 14 and 15 (75%, 3:2; Scheme 1), and the D-galactosylidene-derived diazirine 17 to 22 and 23 (52% (from 16)), 65:35; Scheme 2). The reaction of phenol with 17 yielded 58% (from 16) of the O-galactosides 18 and 19 (4:1) and 14% of the C-galactosides 20 and 21 (1:1). From the D-mannosylidene-derived diazirine 25, we predominantly obtained the .alpha.-D-configurated 26 (38% from 24). These results are interpreted by assuming that an intermediate (presumably a glycosylidene carbene) first deprotonates the phenol to generate an ion pair which combines to give O- and -with electron-rich phenolates-also C-glycosides. A competition experiment of 3 with 4-nitro- and 4-methoxyphenol gave the products from the former (14 and 15) and the latter phenol (4-7) in almost equal amounts. Differences in the kinetic acidity of OH groups, however, may form the basis of a regioselective glycosidation, as evidenced by the reaction of 3 with methyl orsellinate (1) yielding exclusively the 4-O-monoglycosylated products 27 and 28 (78%, 85:15), although diglycosidation is possible (27 .fwdarw. 31 and 32; 67%, 4:3; Scheme 3). Steric hindrance does not affect this type of glycosidation; 3 reacted with the hindered BHT (2) to afford 33 and 34 (81%, 4:1). The predominant formation of 1,2-trans-configurated O-aryl glycosides is rationalized by a neighbouring-group participation of the 2-benzyloxy group.