Efficient Synthesis of 1-Aryl-3,4-dihydro-4-hydroxynaphthalene: Application to the Stereocontrolled Synthesis of (±)-Isopicropodophyllin and (±)-Isopodophyllotoxin

摘要

The structural complexities and varied biological activities of aryltetralin lignans, as exemplified by the natural product podophyllotoxin (1), make them challenging synthetic targets. Several methods have become available for the synthesis of podophyllotoxin (1) and its congeners. Rodrigo et al. reported the synthesis of (±)-isopicropodophyllin (2) and (±)-isopodophyllotoxin (3) from piperonal via hydrogenolysis of the Diels-Alder adduct in 22% and 20% overall yields, respectively. They also reported the isolation of the dihydronaphthol 4 (20%) as unexpected byproduct during a hydrogenolysis of the adduct.