Asymmetric Synthesis of Unsaturated Mono- and Bicyclic Prolines

Asymmetric Synthesis of Unsaturated Mono- and Bicyclic Prolines 

The extension of the synthesis of the unsaturated monocyclic prolines to that of bicyclic prolines 64 furnished some unexpected results. 

It is assumed that salts /Z-77 contained in the organic phase undergo an anion exchange with the F ion, which acts as a base and causes the isomerization to /Z-79. Since the F ion is a weaker nucleophile but a stronger base than the Cl ion, cyclization of 79, rather than substitution as in the case of 72, takes place. 

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