such as FeCl3/H2O2
15 and IBX.16 However, considering steric
constraints in the present system, keto.enol tautomerization
cannot occur in â-ketoester 14. Cerium-catalyzed á-hydroxylation17
under oxygen (1 atm) was studied to yield only
unconverted 14. Finally, the hydroxy was introduced using
Davis oxaziridine18 15 to provide przewalskin B in 71% yield.19
The spectral data of synthetically obtained przewalskin B (1H
NMR, 13C NMR, and HRMS) were in full agreement with
those of the natural product.2