Natural Product Synthesis via Intramolecular Cycloaddition of Nitrogen-Containing 1,3-Dipoles

Abstract

Here we describe our syntheses of polycyclic natural products, including daphenylline, huperzine R, kopsone, and melognine, in which intramolecular cycloadditions of nitrogen-containing 1,3-dipoles played crucial roles in the construction of the cyclic skeletons. Cycloadditions of azomethine ylides resulted in the formation of pyrrolidine rings, which are incorporated into the structures of the target molecules. Cycloadditions of a nitrile oxide or of nitrones formed an isoxazoline or isoxazolidines, respectively, which could be utilized as a β-hydroxyimine or as 1,3-aminoalcohols after cleavage of the N-O bond of the heterocycles.

Graphical Abstract