In situ prepared magnesium salts of ethyl malonate react with 5-X-2-furoyl chlorides (X = Br, NO2, C6H5S and C6H5SO2) to give the corresponding ethyl 5-X-2-furoylmalonates. On treatment of these compounds with secondary amines no nucleophilic substitution of the group X in position 5 of the furan nucleus took place but, instead, amides of 5-X-2-furancarboxylic acids were isolated.
原位制备的乙基马隆酸镁盐与5-X-2-呋喃酰氯(X = Br、NO2、C6H5S和C6H5SO2)反应,得到相应的乙基5-X-2-呋喃酰马隆酸酯。对这些化合物进行二级胺处理时,呋喃核心位置5上的X基团没有发生亲核取代,而是分离出5-X-2-呋喃羧酸酰胺。