反应详情

39.6 g (0.122 moles) of diethyl (2,4-dimethoxy-benzyl-amino)-malonate prepared according to Example (1c) are boiled with 12.3 g (11.2 ml, 0.146 moles) of diketene in 80 ml of glacial acetic acid for half an hour. The glacial acetic acid is distilled off on water bath, in vacuo, the residual oil is crystallized by trituration with 150 ml of water, whereupon the substance is dissolved in 60 ml of ethyl acetate and recystallized by addition of petroleum ether. 29.6 g (60%) of diethyl-N-(2.4-dimethoxybenzyl)-3-hydroxy-3-methyl-5-oxo-2,2-pyrrolidine-dicarboxylate and/or the tautomer thereof are obtained. Melting point: 106° to 107° C.

1. distillationThe glacial acetic acid is distilled off on water bath, in vacuo
2. customthe residual oil is crystallized by trituration with 150 ml of water, whereupon the substance
3. dissolutionis dissolved in 60 ml of ethyl acetate
4. additionrecystallized by addition of petroleum ether