Townsend-Basak-McDonald hypothesis

McDonald and Towne [6] extended studies of Townsend and Basak, [7] and presented an alternative model to the Cane-Celmer-Westley hypothesis ryn-oxidative polycyclization. The Townsend-Basak-McDonald hypothesis for the biosynthesis of monensin A (3) is depicted in Scheme 2. 

A fully satisfying answer to the question of the biosynthesis of polyether compounds such as monensin A (3) cannot be given from the results described here. However, it is clear that the new the Townsend-Basak-McDonald hypothesis has gained ground on the older Cane-Celmer-Westley hypothesis. A key experiment to test the Townsend-Basak-McDonald hypothesis will be the use of labeled (Z,Z,Z)-triens of type 4 in feeding experiments with Streptomyces cinnamonensis. 

Scheme 3. Model reactions of the Townsend-Basak-McDonald hypothesis using PCC as the oxidizing agent.

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