Synthesis of Erythrina and Related Alkaloids.XXIV. Total Synthesis of Erysotrine from 1,7-Cycloerythrinan Derivatives by the Use of a New 1,2-Carbonyl Transposition Method

概要

論文の詳細を見る
Treatment of 2,8-dioxo-1,7-cycloerythrinans with phenylselenenyl chloride in the presence of BF_3・Et_2O as a catalyst gave 3-chloro-3-phenylselenenyl derivaties through the 3-phenylselenenyl derivative, which changed into the Δ^3-3-phenylselenenyl derivative on further reaction.Both the 3-phenylselenenyl and 3-chloro-3-phenylselenenyl derivatives gave the 3,3-dimethoxy derivative on treatment with mercury (II) perchlorate (MPC) in methanol, thus providing a new method for introduction of a masked carbonyl group at the α-position to the original carbonyl group.Thus, the reaction of 1 with phenylselenenyl chloride under acidic conditions followed by MPC treatment in methanol and borohydride reduction gave the 2α-hydroxy-3,3-dimethoxy derivative in 57% yield.This was converted to the conjugated ketone in four steps (72%).The carbomethoxy group of this compound was removed by the CaCl_2-dimethyl sulfoxide-3-ethylpentane-3-thiol method to give the enone 4(70-80%) which isomerized to the conjugated ketone 25c(100%).This ws converted to a natural Erythrina alkaloid, (±)-erysotramidine (5), in four steps (31%), and thence to (±)-erosotrine (6).
社団法人日本薬学会の論文
1991-06-25