Synthesis in the field of podophyllotoxin and related analogues: Part XII - Synthesis of benzodioxan analogue of didemethoxy-beta-apopicropodophyllin

摘要

The benzodioxan analogue of didemethoxy-beta-apopicropodophyllin 15 has been synthesized starting from 6. On Stobbe condensation of 2,3-dihydro-benzo1,4]dioxin-6-yl-(4-methoxyphenyl)methanone 6 with diethyl succinate gives 7 which on reduction with sodium amalgam yields 8. Cyclisation of 8 with PPA furnishes tetralone ester 10. Formylation of 10 with ethyl formate and sodium hydride affords 11, which on sodium borohydride reduction followed by alkaline hydrolysis and finally on treatment with p-toluenesulphonyl chloride gives 15.