The facile bromination by N-bromosuccinimide of benzylidene acetals of carbohydrates. Application to the synthesis of 2,6-imino carbohydrates (substituted 2,5-oxazabicyclo[2.2.2]octanes).
The facile bromination by N-bromosuccinimide of benzylidene acetals of carbohydrates. Application to the synthesis of 2,6-imino carbohydrates (substituted 2,5-oxazabicyclo[2.2.2]octanes).
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碳水化合物的亚苄基缩醛被 N-溴代琥珀酰亚胺轻松溴化。
DOI：
10.1021/jo00826a046
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发表时间：
1970
期刊：
影响因子：
--
通讯作者：
S. Siskin
中科院分区：
文献类型：
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作者：
T. Hullar;S. Siskin
N-溴代丁二酰亚胺（NBS）与高取代度的苄叉缩醛反应，可高选择性地生成溴取代度最低的溴代苯甲酸酯。因此，NBS与甲基2，3-二-O-苯甲酰基-4，6-O-亚苄基-α：-D-吡喃葡萄糖苷（6）、甲基2-苯磺酰氨基-4，6-O-亚苄基-2-脱氧-α D-吡喃阿卓糖苷（1）和甲基4，6-O-亚苄基-2-脱氧-2-（对甲苯磺酰氨基）-3-0-（对甲苯磺酰基）-α D-吡喃阿卓糖苷（10）反应，以高产率得到相应的4-O-苯甲酰基-6-溴-6-脱氧衍生物7、2和11。在甲醇钠溶液中，2顺利地转化为取代的2，5-氧氮杂双环-[2.2。2]辛烷，甲基。N-苯磺酰基-2，6-二脱氧-2，6-亚氨基-α D-吡喃阿卓糖苷（3），而11迅速转化为取代的3，7-氧氮杂双环[4.1. 0]庚烷（15）。苄叉缩醛与NBS的反应为2，6-亚氨基糖衍生物的合成提供了便利条件，条件是良好的离去基团不与氮官能团的反式邻位，6-脱氧-6-卤代糖是重要的合成中间体，但它们的制备往往是一个复杂的过程。本文报道了用N-溴代丁二酰亚胺（NBS）溴化-氧化4，6-O-亚苄基取代糖，生成4-O-苯甲酰基-6-溴-6-脱氧取代糖的方法。1· 8-8通过中间体甲基2-苯磺酰氨基-4-0-苯甲酰基-6-溴-2，6-二脱氧-aD-吡喃阿卓糖苷（2）将甲基2-苯磺酰氨基-4，6-0-苯亚甲基-2-脱氧-aD-吡喃阿卓糖苷（1）方便地转化为双环糖甲基N-苯磺酰基-2，6-二脱氧-2，6-亚氨基-aD-吡喃阿卓糖苷（3），证明了该反应的实用性。9通过N-溴代琥珀酰亚胺的氧化。在其他工作过程中，有必要研究NBS对2-（2-甲基苯基）二氧戊环（4）的影响。
N-Bromosuccinimide (NBS) reacts very selectively with highly substitutedbenzylidene acetals to givebromo benzoates in which the bromine occupies the least substituted carbon. Thus, NBS reacted with methyl 2, 3-di-0-benzoyl-4, 6-0-benzylidene-a:-D-glucopyranoside (6), methyl 2-benzenesulfonamido-4, 6-0-benzylidene-2-deoxy-aD-altropyranoside (1), and methyl 4, 6-0-benzylidene-2-deoxy-2-(p-tolylsulfonamido)-3-0-(p-tolylsulfonyl)-aD-altropyranoside (10) to give high yields of the respective 4-0-benzoyl-6-bromo-6-deoxy derivatives 7, 2, and 11. In methanolic sodium methoxide, 2 was smoothly converted to the substituted 2, 5-oxazabicyclo-[2.2. 2] octane, methyl. V-benzenesulfonyl-2, 6-dideoxy-2, 6-imino-aD-altropyranoside (3), whereas 11 was rapidly converted to the substituted 3, 7-oxazabicyclo [4.1. 0] heptane (15). The reaction of benzylidene acetals with NBS therefore offers a convenient entryinto 2, 6-imino sugar derivatives, provided a good leaving group is not irans-vicinal to the nitrogen function.The 6-deoxy-6-haIo substituted sugars are important synthetic intermediates, 2 but their preparation is often an involved process. This paper describes the facile formation of 4-0-benzoyl-6-bromo-6-deoxy substituted sugars by bromination-oxidation of4, 6-O-benzylidene substituted sugars with N-bromosuccinimide (NBS). 1· 8-8 The utility of this reaction is demonstrated by con-venient conversion of methyl 2-benzenesulfonamido-4, 6-0-benzylidene-2-deoxy-aD-altropyranoside (1) into the bicyclic sugar, methyl iV-benzenesulfonyl-2, 6-dideoxy-2, 6-imino-aD-altropyranoside (3) via the inter-mediate methyl 2-benzenesulfonamido-4-0-benzoyl-6-bromo-2, 6-dideoxy-aD-altropyranoside (2). 9 Oxidation by N-Bromosuccinimide.—During the course of other work it became necessary to study the effect of NBS on 2-(2-methylphenyl) dioxolane (4).