| Abstract
| - A general method for total synthesis of natural trisubstituted γ-lactones is developed on the basisof the chemistry of alkynyltungsten compounds. The key step in this approach involves thecycloalkenation of tungsten−η1-(3R,4S)-pent-1-yne-3,4-diol with aldehydes to give tungsten−oxacarbenium salts, further leading to 3-alkylidene-4-hydroxy-5-methyl-γ-lactones upon demetalation. This synthetic sequence proceeds well for alkynylaldehydes and the MOM derivative oftungsten−η1-(3R,4S)-pent-1-yne-3,4-diol. The resulting butyrolactone products are transformed intonatural trisubstituted butyrolactones including (+)-blastmycinone, (+)-blastmycinolactol, (+)-antimycinone, NFX-2, and (+)-isodihydromahubanolide A. By using the same approach based on(R)-ethyl lactate, the natural (−)-litsenolide C1 can be prepared in a few steps.
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