Chemistry of the Podocarpaceae. LXVI. Preparation and reactions of dimethyl 13,14,15,16-Tetranorlabd-8(17)-ene-12,19-dioate

The unsaturated diester (3) is conveniently prepared from the keto diester (2) by using a mixture of zinc, dibromomethane and titanium tetrachloride. Its synthetic utility and that of derived products has been explored.