Cyclic hydroxycarboxylic acids. II. Lactonization reactions on 2-Hydroxycyclopentanecarboxylic acids and 3-Hydroxyprolines

Abstract

The racemates of cis-2-hydroxycyclopentanecarboxylic acid and of cis-3- hydroxy-N-tosylproline yield corresponding β-lactones upon treatment with cold tosyl chloride-pyridine. Similar treatment of trans-2- hydroxycyclopentanecarboxylic acid gives cyclopent-1-enecarboxylic acid, but trans-3-hydroxy-N-tosylproline is unchanged. Unlike in other 3-hydroxyprolines, the proline protons in the N-tosyl β-lactone have a completely first-order p.m.r. spectrum which is analysed.