Download Rapid, Controlled Assembly of Polyenes for Studying Pericyclic

Rapid, Controlled Assembly of Polyenes
for Studying Pericyclic Reaction Cascades
David A. Vosburg, Department of Chemistry, Harvey Mudd College
Pericyclic reactions are among the most
powerful transformations in organic chemistry,
and they are even more impressive when they
occur in tandem. Outstanding examples of
pericyclic reaction cascades are found in the
biosyntheses of the endiandric acids, a family
of cyclic polyketides isolated from the
Australian
plant
Endiandra
introrsa
(Lauraceae). Inspired by the cascades of
cyclizations in the biogenesis of these natural
products, we are using synthetic and
computational approaches to study the
selectivity and scope of these reaction
cascades.
H
H
HO2C
Ph
Ph
CO2H
CO2H
Ph
H
H
H
endiandric acid G
Ph
H
H
H
H
H
H
CO2H
HO2C
H
H
H
H
CO2H
H
H
H
endiandric acid B
endiandric acid F
endiandric acid C
We have successfully computed an energetic map of the pericyclic reaction cascade above that leads to endiandric
acids B, C, F, and G and have made substantial progress towards the synthesis of polyenes for use in this and related
cascades. A highlight is the rapid synthesis of the enyne building blocks below from a common precursor.
Ph
TMS
NMe
O
O
(HO)2B
O B
O
TMS
t-BuO2C
TMS
Ph
TMS
MeO2C
TMS
Ph