反应详情

125 g (630 mmole) 3,3-dimethyl-1,5-dioxa-spiro[5,5] undecan-8-one, which was obtained by the azeotropic acetylation of cyclohexane-1,3-dione with 2,2-dimethylpropane-1,3-diol in toluene as a solvent using p-toluenesulphonic acid as a catalyst, and 59 g (630 mmole) dimethylammonium methylene chloride were stirred at room temperature in 400 ml of dry acetonitrile. After adding 1 ml acetyl chloride the mixture was stirred for a further 3 hours at room temperature, whereupon a clear colourless solution was obtained. 800 ml of dry ether were then added drop-wise to the reaction mixture, whereupon the hydrochloride crystallised out. 158 g of (18) were obtained (98% theoretical).