GoKawiilPalladium catalysis enables stereocontrolled ketone homologation without diazo reagents
Researchers developed a palladium(II)/(IV)-catalyzed decarboxylative rearrangement that converts β-hydroxy carboxylic acids into homologated ketones and aldehydes through a concerted mechanism, rather than the radical or carbocation steps used in earlier electrochemical versions from 1960. The method proceeds via a six-membered Pd(IV) intermediate that fragments with carbon migration and loss of carbon dioxide, preserving stereochemical information at the migrating carbon while inverting the adjacent center. The team demonstrated its practical value by using this rearrangement as a key step in a short total synthesis of the natural product (+)-rupestine D.