High-Field FT NMR Application of Mosher’s Method. The Absolute Configurations of Marine Terpenoids

Ikuko Ohtani, Takenori Kusumi, Yoel Kashman*, Hiroshi Kakisawa

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Mosher’s (1H) method to elucidate the absolute configuration of secondary alcohols was reexamined by use of high-field FT NMR spectroscopy, which enables assignment of most of the protons of complex molecules. There is a systematic arrangement of d (ds - &R) values obtained for the (R)- and (S)-MTPA esters of (−)-menthol, (−)-borneol, cholesterol, and ergosterol, the absolute configurations of which are known. Analysis of the?d values of these compounds led to a rule that could predict the absolute configurations of natural products. When this rule was applied to some marine terpenoids including cembranolides and xenicanes, their absolute configurations were assigned and a part of the results were confirmed by X-ray structural analyses. In the case of sipholenol A, which has a sterically hindered OH group, this rule is inapplicable. But the problem is overcome by inverting the OH group to a less sterically hindered position; the resulting epimer gives systematically arranged?d values, which enabled the elucidation of the absolute configuration. Comparison of the present method with Mosher’s 19F method indicates that the latter one using 19F NMR lacks in reliability.

Original languageEnglish
Pages (from-to)4092-4096
Number of pages5
JournalJournal of the American Chemical Society
Issue number11
StatePublished - 1 May 1991


Dive into the research topics of 'High-Field FT NMR Application of Mosher’s Method. The Absolute Configurations of Marine Terpenoids'. Together they form a unique fingerprint.

Cite this