【摘要】 <正> 我们前文以1-溴-4-氧-戊烷的乙二醇缩酮制成格氏试剂,再与草酸二乙酯反应,成功地得到相应的α-酮酸酯(Ⅳ)。为推广制备α-酮酸(酯)的一般方法,我们经反复试验,在无水、绝氧、低温及较短的反应时间等条件下,格氏试剂与草酸二乙酯作用,产品经亚硫酸氢钠加成物纯化,得到了收率较高,纯度好的七种α-酮酸酯:5-甲基-2-氧-已酸乙酯(Ⅰ),6-甲基-2-氧庚酸乙酯(Ⅱ),2-氧辛酸乙酯(Ⅴ),4-甲基-2-氧戊酸乙更多还原

【Abstract】 α-keto esters are key intermediates for synthesizing cephalotaxine ester alkaloids which exhibit antitumor activity. Therefore, it is very important to study their synthetic methods. This paper reports a modified method for synthesizing a-keto esters. Reaction of Grignard reagent and diethyl oxalate in the absence of water and oxygen under the condition of low temperature and short reaction time afforded the following a-keto esters. Ethyl 5-methyl-2-oxo-caproate(Ⅰ) in 92% yield; Ethyl 6-methyl-2-oxo-heptoate(Ⅱ) in 88% yield; Ethyl 5-ethylene ketal of 2,5-dioxo-caproate(Ⅲ) in 63% yield; Ethyl 6-ethylene ketal of 2,6-dioxo-heptoate(Ⅳ) in 54% yield; Ethyl 2-oxo-octoate (Ⅴ) in 98% yield; Ethyl 4-methyl-2-oxo-valerate (Ⅵ) in 60% yield; and Ethyl 2-oxo-valerate(Ⅶ) in 51% yield. Their structures were proved by their MS and HNMR spectra. Four of them (Ⅰ,Ⅱ,Ⅲ,Ⅳ) have been applied respectively in synthesizing deoxyharringtonine, homo-deoxy harringtonine, harringtonine, and homoharringtonine.更多还原