NHC-Catalyzed Desymmetrization in Natural Product Synthesis

Significance

Scheidt and co-workers report the synthesis of three bakkenolide natural products, employing their previously developed carbene-­catalyzed desymmetrization of 1,3-diketones (J. Am. Chem. Soc. 2007, 129, 10098) as an early key step. Diketone 2 was cyclized in the presence of the A-derived carbene to give β-lactone 3 in good yield and excellent enantioselectivity. Another interesting aspect is the double-bond isomerization of 5 to 6 prior to the reduction to obtain 7 with an equatorial methyl group. The final steps were adapted from a related work by Greene, Deprés, and co-workers (J. Am. Chem. Soc. 1996, 118, 9992).