Conversion of pravastatin into an advanced intermediate for the synthesis of the HMG-CoA reductase inhibitor BB-476

Rearrangement of the decalin system of pravastatin under SN2′ Mitsunobu conditions and subsequent selective hydrolysis and oxidation afforded a key dienone 23, which upon copper-catalyzed addition of a 1E-propenyl moiety established the carbon framework of BB-476 3 in high diastereomeric excess.