Synthese makrocyclischer Ketone durch Ringerweiterung; ein neuer Weg zu(±)‐Muscon

Synthesis of Macrocyclic Ketones by Ring‐Enlargement Reactions; a New Path to (±)‐Muscone A new synthetic route to macrocyclic ketones is described. Starting from 2‐nitrocycloalkanones, the ring‐enlarged compounds of the type 4 and 5 were prepared in three steps. Reduction of the NO 2 group with Bu 3 SnH and azobisisobutyronitrile led in moderate yields to simple β‐keto‐esters which were quantitatively hydrolyzed and decarboxylated to the ketones of the type 8 and 9 . The interesting fragrances Exaltone ® ( 8a ) and (±)‐muscone ( 9a ) were prepared in this way in overall yields of 22 and 18%, respectively.