Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
J Org Chem. 2010 Feb 5;75(3):741-7. doi: 10.1021/jo902245q.
A number of N-substituted azacalix[4]pyrimidines were synthesized by two methods. While straightforward condensation reaction between 4,6-dichloropyrimidine and 4,6-bis(alkylamino)pyrimidines gave identically N-substituted azacalix[4]pyrimidines in low yields, a general and moderate-to-high yielding 1 + 3 macrocyclic fragment coupling reaction afforded azacalix[4]pyrimidines that contained either the same or different N-substituents. Upon treatment with N-bromosuccinimide (NBS) under controlled conditions, methylazacalix[4]pyrimidine was selectively brominated at lower rim to produce mono-, di-, and tribrominated azacalix[4]pyrimidines in good yields. While azacalix[4]pyrimidine derivatives adopted 1,3-alternate conformation in the solid state, the synthesized macrocycles were fluxional in solution, and the interconversion of various conformational structures was rapid relative to the NMR time scale.
通过两种方法合成了多个 N-取代的氮杂杯[4]嘧啶。虽然 4,6-二氯嘧啶与 4,6-双（烷基氨基）嘧啶之间的直接缩合反应以低产率得到相同的 N-取代的氮杂杯[4]嘧啶，但一般且中等至高产率的 1 + 3 大环片段偶联反应得到了含有相同或不同 N-取代基的氮杂杯[4]嘧啶。在受控条件下用 N-溴代丁二酰亚胺 (NBS) 处理时，甲基氮杂杯[4]嘧啶在较低的边缘选择性地溴化，以高产率得到单、二和三溴化氮杂杯[4]嘧啶。虽然氮杂杯[4]嘧啶衍生物在固态中采用 1,3-交替构象，但合成的大环在溶液中是动态的，并且各种构象结构的相互转化相对于 NMR 时间尺度是快速的。
