Total Synthesis of Triplinone F

The
first total synthesis of triplinone F, along with its C11 epimer,
has been executed to establish, inter alia, the stereochemistry
of C11 and its complete absolute configuration. The terminal styrene
unit was added by cross-metathesis, whereby 1,3-diol units on either
side of the central olefin were taken from malic acid enantiomers
and coupled by a Yamaguchi alkyne–epoxide opening protocol.
The C11 stereochemistry was manipulated by Noyori asymmetric ynone
reduction. The Z-selective reduction of alkynoate
and acid-catalyzed lactonization forged the right-hand-side 5,6-dihydro-δ-pyrone
unit.