Two Practical and Efficient Approaches to Fluorinated and Nonfluorinated Chiral beta-Imino Sulfoxides.
Two Practical and Efficient Approaches to Fluorinated and Nonfluorinated Chiral beta-Imino Sulfoxides.
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DOI：
10.1021/jo980336f
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发表时间：
1998-08
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影响因子：
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通讯作者：
S. Fustero;A. Navarro;B. Pina;A. Asensio;P. Bravo*;M. Crucianelli;A. Volonterio;M. Zanda
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文献类型：
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作者：
S. Fustero;A. Navarro;B. Pina;A. Asensio;P. Bravo*;M. Crucianelli;A. Volonterio;M. Zanda
将含氟和非氟化的N-取代亚胺基氯化物1与对映体甲基对甲苯基亚砜2a(或外消旋甲基苯基亚砜2b)的锂衍生物反应，得到了多种手性N-取代的β-亚胺基亚砜4。标题化合物(R)-4也是由γ-氟-β-酮亚硫醚(R)-5和N-芳基亚胺基膦6通过aza-Wittig反应合成的。亚氨基-烯氨基平衡研究表明，在所有情况下，亚氨基形式是主要的互变异构体，与N-取代基的性质无关。N-烷基和N-芳基衍生物的C=N双键构型均为Z，这是根据(1)对几种化合物进行的H-核磁共振NOE差异实验得出的结果。对1和4的几个典型例子进行的从头计算(HF/6-31G)与实验结果基本一致。
Reaction of fluorinated and nonfluorinated N-substituted imidoyl chlorides 1 with lithium derivatives of enantiopure methyl p-tolyl sulfoxide 2a (or racemic methyl phenyl sulfoxide 2b) gave a wide variety of chiral N-substituted beta-imino sulfoxides 4 in good to excellent yields. The title compounds (R)-4 were also prepared by aza-Wittig reaction of gamma-fluoro-beta-keto sulfoxides (R)-5 and N-aryl iminophosphoranes 6. The imino-enamino equilibrium was studied, showing, in all instances, the imino form as the predominant tautomer independent of the nature of the N-substituent. The configuration of the C=N double bond was found to be Z for both N-alkyl and N-aryl derivatives on the basis of (1)H NMR NOE difference experiments performed over several compounds. Ab initio calculations (HF/6-31G) carried out on several representative examples of 1 and 4 are, in general, consistent with the experimental results.