Ringerweiterung durch Fragmentierung. Synthese von 15-Pentadecanolid (Exaltolid®)

Ring Enlargement by Fragmentation. Synthesis of 15-Pentadecanolide (Exaltolide®) The title compound was synthesized from 1-(3′-hydroxypropyl)-2-oxocyclododecane-1-carbonitrile ( 3 ), using two different routes (Scheme). The CN group of 3 was converted to the Me₃N⁺ residue in 5 which underwent, upon NaH treatment, a fragmentation leading to the ring-enlargement product 6 . The same product was observed after heating the ring-enlarged dimethylamine oxide 14 , prepared from 3 by Bu₄NF treatment and conversion of the CN into the dimethylamine-oxide moiety. Ozonolysis of the methylidene double bond in 6 and reduction of the resulting C = O to a CH₂ group gave Exaltolide® ( 8 ).