Esters, 1,2-keto Knoevenagel reaction, oxidation

Let us start with alcohol 5. The results obtained in die deuteration experiment confirm that 5 was obtained by oxidation of die expected Knoevenagel product 3. Thus, P-keto ester enolate 9 is already formed in die reaction medium and does in fact lead to the desired unconjugated tricycle 3, although diis compound undergoes rapid oxidation and cannot be isolated (Scheme 1.5). Evidently, further oxidation of the alcohol 5 leads to the tricyclic ketone 6, which is also detected in the reaction mixture. 

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