Dynamic helical chirality of an intramolecularly hydrogen-bonded bisoxazoline.
Dynamic helical chirality of an intramolecularly hydrogen-bonded bisoxazoline.
复制标题
分子内氢键双恶唑啉的动态螺旋手性。
DOI：
10.1021/jo026496f
复制
发表时间：
2003
期刊：
影响因子：
--
通讯作者：
J. Parquette
中科院分区：
文献类型：
--
作者：
Adam J. Preston;G. Fraenkel;Albert S Chow;J. Gallucci;J. Parquette
描述了2，6-双-[2-（（4S）-4-甲基-4，5-二氢-1，3-恶唑-2-基）苯基]氨甲酰基吡啶（2）的合成和构象性质。以2-硝基苯甲酰氯为原料，经五步反应制得双恶唑啉2a，总收率为71%。与相关结构如1相比，双恶唑啉2a在溶液和固态中表现出高度偏置的P型螺旋构象。在晶格中，2a进一步组装成沿着晶体学c轴排列的左手螺旋超结构。通过硫代苄基衍生物2b的温度依赖性（1）H NMR光谱的线形分析测量的螺旋相互转化的势垒被确定为相当低（（Delta）G（++）= 12.3 kcal/mol），表明存在高度动态的螺旋手性。
The synthesis and conformational properties of 2,6-bis-[2-((4S)-4-methyl-4,5-dihydro-1,3-oxazol-2-yl)phenyl]carbam oylpyridines, 2, have been described. Bisoxazoline 2a was prepared in five steps from 2-nitrobenzoyl chloride in an overall yield of 71%. In contrast to related structures such as 1, bisoxazoline 2a exhibits a highly biased P-type helical conformation in solution and in the solid state. In the crystal lattice, 2a further assembles into a left-handed helical superstructure aligned along the crystallographic c axis. The barrier to helical interconversion, as measured by line-shape analysis of the temperature-dependent (1)H NMR spectra of thiobenzyl derivative 2b, was determined to be quite low ((Delta)G(++) = 12.3 kcal/mol), indicating the presence of a highly dynamic helical chirality.