The synthesis of R-3-alkoxy-1-(1′-hydroxyethyl)-4-methoxy-2-(1″-propenyl)benzenes utilizing Corey–Bakshi–Shibata asymmetric reductions

Pyrolysis of the 3-O-allyl derivative of isovanillin followed by alkylation of the derived allylphenol afforded a series of benzaldehyde derivatives each of which was transformed by initial treatment with methylmagnesium bromide followed by oxidation of the corresponding alcohols with activated manganese dioxide into a series of ketones . Palladium(0) catalysed isomerization of the double bond in the prop-2′-enyl side-chain afforded ketones which were subjected to the Corey–Bakshi–Shibata asymmetric reduction protocol to afford the R-3-alkoxy-1-(1′-hydroxyethyl)-4-methoxy-2-(1″-propenyl) benzenes in yields of approximately 60% and with eeʹs of 75%.