Synthesis of Phenol Abietane Diterpenes Based on the Oxidative Radical Cyclization Utilizing the Mn(OAc)3/Ac2O System.

A new route to phenol abietane diterpenes from TRANS-communic acid is reported. The key step is the transformation of a ?-ketoester into the corresponding O-acetylsalicilate, via a manganese(III)-based oxidative free-radical cyclization carried out in Ac 2O. Utilizing this, the first synthesis of (-)-sugikurojin A has been achieved. The immunosuppressor 19-hydroxyferruginol has also been synthesized. [ABSTRACT FROM AUTHOR]