CORRELATION OF CONFIGURATION AND F-19 CHEMICAL-SHIFTS OF ALPHA-METHOXY-ALPHA-TRIFLUOROMETHYLPHENYLACETATE DERIVATIVES
CORRELATION OF CONFIGURATION AND F-19 CHEMICAL-SHIFTS OF ALPHA-METHOXY-ALPHA-TRIFLUOROMETHYLPHENYLACETATE DERIVATIVES
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DOI：
10.1021/jo00952a006
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发表时间：
1973-01-01
影响因子：
3.6
通讯作者：
MOSHER, HS
中科院分区：
文献类型：
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作者：
SULLIVAN, GR;DALE, JA;MOSHER, HS
经验推导了非对映异构体a-甲氧基-a-三氟甲基苯乙酸（MTPA）酯和酰胺的构型与16F化学位移的相关性。数据已根据配置相关模型进行了合理化处理。固有的大16F化学位移（CDC13溶剂，外部三氟乙酸）及其在核磁共振光谱中不拥挤区域的位置使得这种相关性在涉及手性仲醇和伯胺的立体化学研究中具有相当大的价值。在研究的25个例子中，19个MTPA酯类和6个MTPA酰胺类，其中18个明显地以一种一般模式分组，并根据构型相关模型进行了讨论。3种MTPA酯对R、RS、S与R、SS、R非对映体之间的19F-CFa信号没有明显的化学位移不等效性。在异丁基-íerí-butylcarbinol、正丁基丁基甲醇、三氟甲基丁基甲醇和冰片这四种可能被视为该核磁共振构型相关模型例外的情况中，前三种情况可以合理化，而只有冰片是该模型的明显例外。所研究的6种MTPA非对映体酰胺均符合同一模型。各种非对映体酯和酰胺的不等效性已被用于手性醇和胺的对映体组成的定量测定。这些研究最近已经扩展到包括这些灾难的质子核磁共振化学位移差异的构型的相关性
An empirically derived correlation of configuration of diastereomeric a-methoxy-a-trifluoromethylphenvl-acetic (MTPA) esters and amides with the 16F chemical shifts has been developed. The data havebeen rational-ized in terms of a configuration-correlation model 5. The inherently large 16F chemical shifts (CDC13 solvent, external trifluoroacetic acid) and their location in an otherwise uncongested region of the nmr spectrum makes this correlation of considerable value in connection with stereochemical studies involving chiral secondary alcohols and primary amines. Of the 25 examples studied, 19 MTPA esters and 6 MTPA amides, 18 clearly group themselves in a general pattern which is discussed in terms of the configuration-correlation model. Three MTPA esters showed no significant chemical shift nonequivalence for the 19F-CFa signals between R, RS, S vs. R, SS, R diastereomers. Of the four cases which might be considered exceptions to this nmr configurational correlation model, namely isobutyl-íerí-butylcarbinol, n-butyl-ierf-butylcarbinol, trifluoromethyl-ierf-butyl-carbinol, and borneol, the first three can be rationalized while only borneol stands as a clear exception to the model. All of the 6 MTPA diastereomeric amides studied conform to the same model.The nonequivalence of various diastereomeric esters and amideshas been utilized for the quantitative deter-mination of enantiomeric composition of chiral alcohols and amines. 3 These studies recently have been ex-tended to include correlations of configurations with proton nmr chemical shift differences of these diastere-