End game strategies towards the total synthesis of vibsanin E, 3-hydroxyvibsanin E, furanovibsanin A, and 3-O-methylfuranovibsanin A

• Brett D. Schwartz,
• Craig M. Williams and
• Paul V. Bernhardt

Beilstein J. Org. Chem. 2008, 4, No. 34, doi:10.3762/bjoc.4.34

• procedure based on the epoxidation of silyl enol ethers. Ketone 23 was smoothly converted into the TBS enol ether 27 (85% yield) with TBS triflate, which was then treated with dimethyldioxirane (DMDO). When work up was restricted to a simple 1 M hydrochloric acid wash (i.e. separatory funnel) only the

• oxidation on diketone 40, but to first protect the ketone functionality as silyl enol ethers as was undertaken in Scheme 7 (i.e. 27–48). Treating diketone 40 with t-butyldimethylsilyl trifluoromethanesulfonate afforded only the monoprotected product 53 (crude yield 55%), which smoothly underwent reduction