Practical Demethylation of Podophyllotoxin and Efficient Preparation of 4-Amino-4-deoxy-4′-demethylepipodophyllotoxin
摘要:
4'-Demethylepipodophyllotoxin (4'-DMEP) was readily available through demethylation of podophyllotoxin using methionine in methanesulfonic acid in the presence of TFA (or acetone/water). Thus, 4-amino-4-deoxy-4'-demethylepipodophyllotoxin was obtained in three steps in excellent yield by a Ritter reaction on 4'-DMEP, followed by treatment with thiourea in AcOH.