Lactones Vilsmeier-Haack reaction

Vilsmeier-Haack-type reaction provided the C ring of the Aspidosperma skeleton, and elaboration of the E ring was achieved by the addition of a radical generated from the xanthate derivative of the primary alcohol to give nonacyclic compound 111. The final steps for the completion of the total synthesis consisted of the formation of a lactone ring, which was achieved by oxidation of the tertiary amine with potassium ferricyanide,... 

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