An effective synthesis of (E)-4-oxo-5-hexenals 6 and the acetals 5 starting from ethyl 2-alkoxy-1-cyclopropanecarboxylates 1a-d is presented. The acid-induced ring opening of the cyclopropanecarboxylates 1a, b, followed by phosphorylmethylation or the phosphorylmethylation of the ester 1c followed by ring opening leads to the 5-acetal of 2,5-dioxopentylphosphonate 4. The Horner-Emmons olefination of 4 with various aldehydes produces the title compounds.
本研究展示了一种从乙基2-烷氧基-1-
环丙烷羧酸酯1a-d出发,合成(E)-4-氧-
5-己烯醛6及其
缩醛5的有效方法。首先,
环丙烷羧酸酯1a、b在酸性诱导下环开裂,随后进行膦甲基化,或者先对酯1c进行膦甲基化后环开裂,得到2,5-二氧戊基
膦酸酯的5-
缩醛4。通过Horner-Emmons烯化反应,4与各种醛反应,生成目标化合物。