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本文报道脱氧三尖杉酯碱(Ⅵa)和高三尖杉酯碱(Ⅵc)的不对称合成。采用(+)R-对甲苯亚磺酰基乙酸叔丁酯(Ⅰ)与相应的三尖杉碱酮酸酯(Ⅱa)、(Ⅱb)进行立体选择性缩合反应,经过若干步骤,合成了具有C_2′R构型的(Ⅵa)和(Ⅵc)。中间产物(Ⅲa),(Ⅲb)或(Ⅲc)以铝汞齐脱硫得(Ⅳa、(Ⅳc)。再以三氟醋酸处理,选择性水解叔丁酯得(Ⅴa)、(Ⅴc)。最后以重氮甲烷甲酯化。再次证实了(+)R-对甲苯亚磺酰基乙酸叔丁酯(Ⅰ)具有较高的立体选择性反应。
This paper reports the asymmetric synthesis of homoharringtonine (VIa) and homoharringtonine (Ⅵc). The stereoselective condensation reaction of tert-butyl (+) R-p-toluenesulfinyl acetate (Ⅰ) with the corresponding behenylcarnone esters (Ⅱa) and (Ⅱb) was carried out. (VIa) and (VIc) of the ’R’ configuration. The intermediate product (Ⅲa), (Ⅲb) or (Ⅲc) is desulfurized with aluminum amalgam (Ⅳa, (Ⅳc) .Then treated with trifluoroacetic acid, Diazomethane methyl esterification.It was confirmed again that the (+) R-tert-butyl-tosyl acetate tosylate (I) has a higher stereoselectivity.