(e) -2 - (3 - Chloro - 1 - Methyl - 1 - Propenyl) -5,5 - Dimethyl-1 ,3 - Two (mouth Of Evil) Alkyl, Synthesis And Optimization,

As an important intermediate, (E)-2-(3~chloro-l-propenyl)-5,5-dimethyl-l,3-dio-xane has been used widely in the synthesis of medicines. A new route consisting of oxidation, aldehyde group protecting, ester exchanging and substituting by chloride is studied because of the available raw materials, short reaction steps, moderate reaction temperature and high yield etc.To get the high yield of the whole reaction route, single-factor optimization is adopted in this paper. In the first step of oxidation, reaction temperature and feed-in mode play important roles. The yield is 81.2% when reaction temperature is 80℃, stirring rate is 500 rpm, reaction time is 24h, dropping time of the raw material l-chloro-4-acetoxy-2-methyl-2-buten is 21h and the ratio of catalyst to dipotassium hydrogen phosphate to potassium dihydrogen phosphate to the raw material equals to 0.12:0.14:1.27:1. In the second step, 95.5% yield is obtained when the ratio of p-toluenesulfonic acid to neopentyl glycol to the material equals to 0.002:1.05:1 at reduced pressure in solvent A. In the third step, side reactions can be reduced when the potassium hydroxide is used as catalyst, and the yield is 96.7% when reaction temperature is 40℃ and the ratio of potassium hydroxide to methanol to the raw material equals to 0.3:6:1. In the final step, when the ratio of thionyl chloride to dimethylformamide to the raw material to solvent B equals to 1.2:3.5:1:10 in -10℃, the yield is 91.5%.