Synthesen makrocyclischer Lactone durch Ringerweiterung Herstellung von (±)‐Phoracantholid I, (±)‐Dihydrorecifeiolid und (±)‐15‐Hexadecanolid

Syntheses of Macrocyclic Lactones by Ring Enlargement Reaction Reaction. Preparation of (±)‐Phoracantholide I, (±)‐Dihydrorecifeiolide and (±)‐15‐Hexadecanolide A general procedure for the synthesis of macrocyclic lactones is described. The Michael adducts of 2‐nitrocycloalkanones and acrylaldehyde were regiospecifically methylated with CH3Ti[OCH(CH3)2]3 or (CH3)2Ti[OCH(CH3)2]2 at the aldehyde carbonyl group. Treatment of the so‐formed alkohols with tetrabutylammonium fluoride gave the lactones enlarged by four ring members. This method was used to synthesize the 10‐membered (±)‐phoracantolide I (11), the 12‐membered (±)‐dihydrorecifeiolide (17), and (±)‐15‐hexadecanolide (24) in 52%, 26.5%, and 58.7% respectively.