Synthesis of Tuckolide, a New Cholesterol Biosynthesis Inhibitor

Tuckolide (decarestrictine D), a 10-membered lactone isolated from P. corylophilum and polyporus tuberaster fungi that potently inhibits cholesterol biosynthesis, was synthesized. The key steps include a Sharpless catalytic asymmetric dihydroxylation reaction (AD) of the methoxymethyl (MOM) ether protected diene 2 and a direct Corey-Nicolaou lactonization reaction of seco-acid 1with added silver perchlorate. The selectivity of the dihydroxylation step was found to be highly dependent on the nature of the protecting group adjacent to the diene in 2. The selectivity of the asymmetric dihydroxylation reaction of 2 indicates that both steric and electronic effects can lead to significant amounts of the undesired isomers. This synthesis establishes the absolute stereochemistry of tuckolide showing the C3 hydroxyl bearing carbon with an S-configuration comparable in an absolute sense to that in the lactone portion of the HMG-CoA reductase inhibitor compactin.