The conversion of cis- into trans-abienol: some reactions with mercuric acetate

Abstract

The diterpenoid alcohol cis-abienol has been converted into trans-abienol by a novel isomerisation with mercuric acetate. trans-Abienol is reduced by sodium and propanol to a mixture of cis- and trans-isodihydroabinenols. On reduction by the di-imide procedure cis- and trans-abienol yield cis- and trans-dihydroabienol, respectively. Mercuration of these two pairs of dihydro-isomers involves participation of the hydroxy-group and, after removal of the acetoxymercuri-group, yields various five- and six-membered ring ethers, the stereochemistry of which are considered on conformational grounds. Five-membered ring oxides can result also from an intramolecular reaction of tetrahydroabienol hypobromite.