Link to Pubmed [PMID] – 12213460
Bioorg. Med. Chem. 2002 Nov;10(11):3463-71
Various 4-analogues of podophyllotoxin and epipodophyllotoxin were obtained via the formation of the corresponding 4-keto derivatives. Methyloximation of podophyllotoxone, followed by subsequent catalytic hydrogenation, gave stereoselective access to 4-alpha-amino-4-deoxypodophyllotoxin and from there, to the corresponding acetamido and formamido derivatives. Base-catalyzed isomerisation of 4-alpha-amino-4-deoxypodophyllotoxin led to the corresponding picropodophyllin isomer while the 4-beta-amino afforded a neopodophyllotoxin-like derivative. On the other hand, oxirane and hydroxymethyl-containing analogues were prepared from podophyllotoxin and 4-epi-4′-demethyl-podophyllotoxin, using a Takai olefination strategy. In the latter series, carboxaldehyde- and carboxylic acid-containing derivatives were also synthesized.