Abstract
The regioselectivity of the palladium(II) oxidation of (±)-17α-vinyl-1,3,5(10)-gonatriene derivatives bearing a lactonic bridge on the α or β-face (β-face: obtention of the expected acetyl derivatives; α-face: presence of aldehydes, anti-Markovnikov addition) may be rationalized by an intramolecular coordination of the metal with the two lactonic oxygen atoms. Calculations carried out using ZINDO I method confirm the existence of such a chelation and the possibility of a cis-hydroxy or a cis-acetoxypalladation in the course of the Wacker process. An experimental confirmation was given by the regioselective mono-oxidation of the vinyl group syn to the methoxycarbonyl group of (3R ∗,6S ∗,9S ∗)-3- methoxycarbonyl-3-(2-propyl)-6,9-divinyl-1-oxaspiro[4.4]nonan-2-one .
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