A short versatile synthesis of aryltetralin lignans including deoxyisopodophyllotoxin and epi-isopodophyllotoxin

Abstract

Cyclisation of tandem conjugate addition products (10), (15), and (20), prepared by reaction of anions derived from benzyl phenyl and benzyl t-butyl sulphides with but-2-en-4-olide, affords a series of aryltetralin lignans belonging to either the ‘normal’ or the ‘retro’ lactone series. Desulphurisation of compound (15) followed by cyclisation, or desulphurisation of the cyclised product (22b), affords deoxyisopodophyllotoxin (5), while treatment of compound (22b) with mercury(II) trifluoroacetate yields epi-isopodophyllotoxin (6).