Model Studies toward the Total Synthesis of Thebaine by an Intramolecular Cycloaddition Strategy

Abstract

Three model compounds required for an approach to thebaine by intramolecular [4+2] cycloaddition were prepared. In the first two cases the anticipated cycloaddition products were obtained under thermal conditions.

Thermolysis of the third, more advanced model compound, afforded products resulting from rearrangements and/or elimination. A study of analogous intra- and intermolecular reactions using benzofuran as dienophile and various electron-poor and electron-rich dienes (pyridazines, pyranones, Danishefsky diene) was undertaken.

Keywords

• cycloaddition
• pyridazine
• thebaine
• thermolysis
• total synthesis