Intramolecular Cycloadditions as a General Strategy for Alkaloid Synthesis. A Novel Formal Synthesis of Lycorine

Article abstract of DOI:10.1021/jo00140a008

The intramolecular <4 + 2> cycloadditions of the aryl-substituted enamido dienes that were produced upon thermal, cheletropic extrusion of sulfur dioxide from the enamides 8,15, and 26 were examined.Whereas thermolysis of 8 in refluxing xylene in the pres