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Article

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

Supporting Info

Félix Freire,^† Felix Calderón,^‡ José Manuel Seco,^† Alfonso Fernández-Mayoralas,^‡ Emilio Quiñoá,^† and Ricardo Riguera*^†

Departamento de Qumica Orgnica, Facultad de Qumica, and Unidad de RMN de Biomolculas Asociada al CSIC, Universidad de Santiago de Compostela, 15782, Santiago de Compostela, Spain and Instituto de Qumica Orgnica General, CSIC, C/Juan de la Cierva, 3, 28006, Madrid, Spain

J. Org. Chem., 2007, 72 (7), pp 2297–2301

DOI: 10.1021/jo061939r

Publication Date (Web): March 8, 2007

Dedicated to Prof. Miguel Yus on the occasion of his 60th birthday.

†

Universidad de Santiago de Compostela.

‡

Instituto de Química Orgánica General.

To whom correspondence should be addressed.

, ricardo@usc.es

Abstract

Comparison of the room- and 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 Δδ^T1T2 for substituents R₁/R₂, but if the relative stereochemistry of the diol is syn, the assignment of its absolute configuration requires the preparation of two derivatives (both the bis-(R)- and bis-(S)-MPA esters), comparison of their room-temperature ¹H NMR spectra, and calculation of the Δδ^RS signs for the methines Hα(R₁) and Hα(R₂) and R₁/R₂ protons. The reliability of these correlations is validated with 17 diols of known absolute configuration used as model compounds.