Oxidative Decarboxylation of Podocarpic Acid Derivatives

Abstract

The radical decarboxylation–sulfoxide cycloelimination of 2′-pyridylthio esters formed from a series of podocarpic acid derivatives gives Δ⁴⁽¹⁸⁾ -alkenes in high yield. An exception is the 13-nitro acid (2) which affords a thiohydroxamic ester (28), the relative stability of which is attributed to inhibition of the radical chain reaction by the nitro group. The stereochemistry of the pyridyl sulfide (18) has been confirmed by X-ray crystallography.