前文报道了异三尖杉酯碱的合成,在合成中形成了两个新的手性碳(C_(2′)和C_(3′)),产物应为四个立体异构体的混合物,由于使用的原料是天然光学活性的三尖杉碱(构型为3S,4S,5R),所以,只需要弄清这些立体异构体中侧链上(C_(2′)和Q_(3′)的绝对构型,就可以确定上述四个立体异构体的绝对构型。在四个立体异构体中,有两个立体异构体的C_(2′)和C_(3′)应为赤式关系,构型分别是2′R,3′S和2′S,3′R;而另两个异构体的C_(2′)和Q_(3′)应为苏式关系,构型分别是2′S,3′S和2′R,3′R。 We have previously reported the synthesis of homoharringtonine, in which two new chiral carbons (C_ (2 ’) and C_ (3’)) are formed. The product should be a mixture of four stereoisomers. Since the starting material used is naturally occurring optically active octreotide (configuration 3S, 4S, 5R), it is only necessary to clarify the side chain of these stereoisomers (C_ (2 ’) and Q_ (3’ ) Absolute configuration of the above four stereoisomers can be determined in the four stereoisomers, there are two stereoisomers C_ (2 ’) and C_ (3’) should be (2’R, 3’S and 2’S, 3’R), while C_ (2 ’) and Q_ (3’) of the other two isomers should be in the Soviet-style relationship, Configurations are 2’S, 3’S and 2’R, 3’R.