Total Synthesis of Aureothin
Résumé
This account reports a program of synthesis of aureothin from genesis to conclusion. The structure of the molecule is moderately complex but relatively dense, and several strategies were explored accordingly to reach the target in an asymmetric manner. The synthetic plan provided an opportunity to demonstrate a new strategy to assemble α′-methoxy-γ-pyrone compounds from readily available building blocks. Hence, the desymmetrization of α,α′-dimethoxy-γ-pyrone by 1,4-addition of 2-lithio-1,3-dithiane gave access to the complete carbon backbone of the target after trapping the resulting vinylogous enolate with the side chain of the target. Following a pattern of kinetic resolution, the remaining cycloetherification relied on P450 cytochrome performing a C–H oxidation with complete enantiodiscrimination. Ultimately, the first asymmetric total synthesis of aureothin was accomplished with a convergent strategy employing a regiodivergent and parallel kinetic resolution of racemic alcohol as a last step.