A Synthesis of Triptoquinones D, E, and F from Podocarpic Acid

Abstract

The First total synthesis of enantiopure triptoquinone F (6) starting from podocarpic acid (10) is reported, as well as formal syntheses of enantiopure triptoquinones D (4) and E (5). An acid-promoted Fries rearrangement of a benzannulated lactone (14) has been used as a direct, moderately high yielding route for introduction of C11 functionality. Treatment of methyl 12-methoxypodocarpa-8,11,13-trien-19-oate (11) with t-butylhydroperoxide and a catalytic amount of ruthenium(III) chloride gives a mixture (1 : 1) of diastereomeric t-butylcyclohexadienones (26) and (28).