Relative and Absolute Stereochemistry of Secondary/Secondary Diols: Low-Temperature <sup>1</sup>H NMR of Their bis-MPA Esters
作者:Félix Freire、Felix Calderón、José Manuel Seco、Alfonso Fernández-Mayoralas、Emilio Quiñoá、Ricardo Riguera
DOI:10.1021/jo061939r
日期:2007.3.1
low-temperature 1H NMR spectra of the bis-(R)- or bis-(S)-MPA ester derivative of an open chain sec,sec-1,2-diol allows the easy determination of its relative stereochemistry and in some cases absolute configuration. If the diol is anti, its absolute configuration can be directly deduced from the signs of ΔδT1T2 for substituents R1/R2, but if the relative stereochemistry of the diol is syn, the assignment of
比较开链仲,仲-1,2-二醇的双-(R)-或双-(S)-MPA酯衍生物的室温和低温1 H NMR光谱,可轻松确定其相对立体化学,有时甚至是绝对构型。如果二醇是抗性的,则其绝对构型可以直接从ΔδT1T2的符号推导出对于取代基R 1 / R 2,但如果二醇的相对立体化学是顺式,则其绝对构型的分配需要制备两种衍生物(双-(R)-和双-(S)-MPA酯) ,其室温的比较1 1 H NMR谱,并计算该Δδ的RS次甲基Hα(R 1)和Hα(R 2)和R 1 / R 2质子的符号。这些相关性的可靠性通过用作模型化合物的已知绝对构型的17种二醇进行了验证。