Direct alkylation of the N3O2-macrocycle 1,12,15-triaza-3,4 : 9,10-dibenzo-5,8-dioxacycloheptadecane (1) with benzyl bromide in the presence of sodium hydrogen carbonate (in the respective molar ratios 1.0 : 2.0 : 1.3) led to a mixture of the mono-, bis-, and tris-N-benzylated derivatives (2)–(6) which were separated using their differential solubilities in warm acetone, fractional crystallization, coupled with column chromatography on silica gel. The X-ray structure of the symmetrical dibenzylated product (4) (as its HNO3 salt) is described. In a parallel study, N-protection of (1) using 1.7 molar equivalents of di-tert-butyl dicarbonate (Boc)2O yielded a mixture from which the symmetrical and unsymmetrical di-protected isomers (8) and (9) were separated by chromatography. Reaction of the symmetrically protected derivative (8) with benzyl chloride in the presence of excess sodium carbonate, followed by removal of the Boc groups, provided an alternative route to the corresponding (symmetrical) mono-N-benzylated macrocycle (2). A similar strategy, involving the use of α,α′-dibromo-p-xylene as a dialkylating agent, was employed to bridge a pair of N-diprotected macrocycles of type (8) or (9) to yield isomeric linked products (12) and (14), respectively. Deprotection of the resulting bis-macrocyclic products gave the 'central' and 'side' linked ligands (13) and (15), respectively.
在碳酸氢钠存在下(各自的摩尔比为 1.0 : 2.0 : 1.3),N3O2-大环 1,12,15-三氮杂-3,4 : 9,10-二苯并-5,8-二氧杂环十七烷(1)与溴化苄直接发生烷基化反应。3) 的条件下,生成了单-、双-和三-N-苄基衍生物 (2)-(6) 的混合物,利用它们在温丙酮中的不同溶解度、分馏结晶以及硅胶柱色谱法将其分离。文中描述了对称二苄化产物(4)(作为其 HNO3 盐)的 X 射线结构。在一项平行研究中,用 1.7 摩尔当量的二碳酸二叔丁酯 (Boc)2O 对(1)进行 N 保护,得到了一种混合物,通过色谱法从中分离出了对称和非对称的二保护异构体(8)和(9)。在过量碳酸钠存在下,对称保护衍生物 (8) 与氯化苄反应,然后除去 Boc 基团,为得到相应的(对称)单-N-苄基大环 (2) 提供了另一条途径。采用类似的策略,即使用 α,α′-二溴对二甲苯作为二烷基化剂,桥接一对 N-二保护的(8)或(9)型大环,分别得到异构连接产物(12)和(14)。对得到的双大环产物进行脱保护处理,分别得到 "中心 "和 "侧 "连接配体(13)和(15)。