An “Aprotic” Tamao Oxidation/ Syn-Selective Tautomerization Reaction for the Efficient Synthesis of the C(1) C(9) Fragment of Fludelone

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  

http://pubs.acs.org/doi/abs/10.1021/ol302221s 

Tamao 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).