Direct Aldehyde Homologation Utilized To Construct a Conjugated-Tetraene Hydrocarbon Insect Pheromone
作者:Richard J. Petroski、Robert J. Bartelt
DOI:10.1021/jf063337e
日期:2007.3.1
New phosphonate reagents were developed for the two-carbon homologation of aldehydes to methyl- or ethyl-branched unsaturated aldehydes and used in the practical synthesis of (2E,4E,6E,8E)-3,5-dimethyl-7-ethyl-2,4,6,8-undecatetraene (1), a pheromone of the beetle Carpophilus lugubris. The phosphonate reagents, diethyl ethylformyl-2-phosphonate dimethylhydrazone and diethyl 1-propylformyl-2-phosphonate
已开发出新的膦酸酯试剂,用于醛类的二碳同系化为甲基或乙基支化的不饱和醛,并将其用于(2E,4E,6E,8E)-3,5-二甲基-7-乙基-2的实际合成,4,6,8-十一碳四烯(1),甲虫Carpophilus lugubris的信息素。膦酸酯试剂二乙基甲酰基-2-膦酸酯二甲基hydr和1-乙基甲酰基-2-膦酸酯二甲基hydr含有一个受保护的醛基,而不是通常的酯基。同源循环需要使试剂与起始醛缩合,然后用稀盐酸和石油醚的双相混合物除去二甲基hydr保护基。该稳健的两步法使用基于酯的Horner-Wadsworth-Emmons试剂代替了标准的三步醛同源法。由(2E)-2-甲基-2-丁烯醛进行的新化合物1的合成以10 g规模运行,仅需五个步骤(两个缩合和脱保护循环,然后进行最后的Wittig烯化),而不是通常的步骤。七。另外,简化了Wittig烯烃化步骤并提高了其E-异构体选择性。整个合成途径的总