A concise route to the common polyketide fragment5of crocacin A-D (1-4) is presented which has previously been converted into all members of this fungicidal and cytotoxic family of dipeptidic natural products by various means. Our synthesis features asyn-selective titanium aldol reaction controlled by a valinol-derived auxiliary, a zinc-mediated, palladium-catalyzedanti-selective addition of propargyl mesylate10to the chiral aldehyde9, as well as a comparison of palladium-catalyzed Stille and Suzuki cross-coupling reactions for the formation of the diene moiety of the target.
本文介绍了一种简明的方法,用于合成蝎子碱A-D(1-4)中的常见多酮片段5,该方法之前已被多种方式转化为这种真菌杀菌和细胞毒素家族的所有成员。我们的合成特点是使用了一种由缬氨醇衍生的辅助剂控制的钛醛反应,并且采用了锌介导的、钯催化的反式选择性丙炔基甲烷磺酸酯10加到手性醛9上的方法,同时比较了钯催化的Stille和Suzuki交叉偶联反应来形成目标化合物的二烯基基团。