Investigation of reactions of CH-acids with generated in situ N-[1,2-bis(methoxycarbonyl)vinyl]pyridinium in the synthesis of 1,2,3,4,5,6,7-hepta(methoxycarbonyl)cycloheptatriene
摘要
The study investigated the reactivity of various CH-acids/conjugated bases in the synthesis of hepta(methoxycarbonyl)cycloheptatriene through a cascade reaction. NMR spectral monitoring identified (methoxycarbonyl)methylpyridinium as the true nucleophilic component in the original synthesis based on methyl diazoacetate. The scope of CH-acids capable of participating in the reaction was expanded to include sulfonium salts and sulfones, whereas certain nucleophiles were found to be ineffective. A correlation between the pKa values of CH-acids and the formation of seven-membered rings in the cascade reaction was established.