The absolute configuration of phomallenic acid C (1), a recently isolated natural antibiotic with a novel mode of action, was previously established in a total synthesis through deduction from the configuration of a key intermediate 4 assigned on an empirical basis. Further experimental evidence is therefore highly desirable. In the present work the absolute configuration of the key propargylic alcohol 4 was determined using the method developed by Mosher. The results show that the previously assigned absolute configuration of 1 is correct.

Key words: Mosher ester, enantiomer, propargylic alcohol, asymmetric reduction, allene