Relative and Absolute Stereochemistry of Secondary/Secondary Diols: Low-Temperature 1H NMR of Their bis-MPA Esters

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• 作者：Fé ; lix Freire ; Felix Calderó ; n ; José ; Manuel Seco ; Alfonso Ferná ; ndez-Mayoralas ; Emilio Qui&ntilde ; oá ; Ricardo Riguera
• 刊名：Journal of Organic Chemistry
• 出版年：2007
• 出版时间：March 30, 2007
• 年：2007
• 卷：72
• 期：7
• 页码：2297 - 2301
• 全文大小：308K
• 年卷期：v.72,no.7(March 30, 2007)
• ISSN：1520-6904

文摘

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Comparison of the room- and low-temperature ¹H NMR spectra of the bis-(R)- or bis-(S)-MPA esterderivative of an open chain sec,sec-1,2-diol allows the easy determination of its relative stereochemistryand in some cases absolute configuration. If the diol is anti, its absolute configuration can be directlydeduced from the signs of fchars/Delta.gif" BORDER=0 >fchars/delta.gif" BORDER=0 >^T1T2 for substituents R₁/R₂, but if the relative stereochemistry of the diol issyn, the assignment of its absolute configuration requires the preparation of two derivatives (both thebis-(R)- and bis-(S)-MPA esters), comparison of their room-temperature ¹H NMR spectra, and calculationof the fchars/Delta.gif" BORDER=0 >fchars/delta.gif" BORDER=0 >^RS signs for the methines Hfchars/alpha.gif" BORDER=0>(R₁) and Hfchars/alpha.gif" BORDER=0>(R₂) and R₁/R₂ protons. The reliability of thesecorrelations is validated with 17 diols of known absolute configuration used as model compounds.