Ozonolysis of alkenes and study of reactions of polyfunctional compounds: LXVIII. synthesis of ω-carboxy derivatives of 20-hydroxyecdysone diacetonide

Ozonolysis of ω-anhydro-20-hydroxyecdysone diacetonide gave a mixture of 24- and 25-oxo derivatives, and only the first of these (23-carbaldehyde) reacted with malonic acid according to Knoevenagel to give 14α-hydroxy-2β,3β: 20,22-bis(isopropylidenedioxy)-6-oxo-27-nor-5β-cholesta-7,24-dien-26-oic acid. The oxidation of 23-carbaldehyde with ozone, followed by treatment with diazomethane, afforded 20-hydroxy-25,26,27-trinorecdysone-23-carboxylic acid methyl ester diacetonide.