An “Aprotic” Tamao Oxidation/ Syn-Selective Tautomerization Reaction for the Efficient Synthesis of the C(1) C(9) Fragment of Fludelone
Tyler J. Harrison, Philippe M. A. Rabbat, and James L. Leighton
oxidation (in this case vinyl silane --> enol) in tandem with
silylformylation and Leighton silylcrotylation was used to build the
C1-C9 fragment of fludelone. A critical transformation in this sequence
is the final tautomerization of the enol to the ketone form.
Previously, Leighton and coworkers carried out Tamao oxidation under
protic conditions; the stereochemistry of the tautomer was dictated by
A-1,3 strain considerations. In this work, they used aprotic conditions
for Tamao oxidation, targeting a likely intramolecular enol-alcohol
H-bonding, which was expected to -- and did -- give the opposite
stereochemistry (the one they actually desired).