Synthesis of totarane diterpenes: totarol, maytenoquinone, 6-deoxymaytenoquinone and 8,11,13-totaratriene-12,13-diol

The syntheses of four totarane diterpenes-totarol, 8,11,13-totaratriene-12,13-diol, 6-deoxymaytenoquinone and maytenoquinone-are described. Totarol was synthesized via cyclization of a modified polyene. 8,11,13-Totaratriene-12,13-diol was prepared from natural totarol by ortho-oxidation with mCBPO (m-chlorobenzoyl peroxide). Maytenoquinone and 6-deoxymaytenoquinone were synthesized from 8,11,13-totaratriene-12,13-diol. 1H-NMR analysis showed that tautomeric isomerization between 6-deoxymaytenoquinone (2-hydroxy-4-quinone methide) and the ortho-quinone was very slow.