2,2-二溴丙烷酸乙酯

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: A stirred solution of 4,5-dimethylcatechol (7.0 g.) in dry acetone (45 ml.) was heated under reflux, then potassium carbonate (5 g.) was added followed by the dropwise addition of ethyl dibromopropionate (3.5 g.). The addition procedure was repeated a further three times over 11/4 hours then the reaction was stirred under reflux for a further 33/4 hours. After cooling, the mixture was filtered, the solids washed well with acetone then the combined filtrate concentrated in vacuo. Water (35 ml.) was added, the resulting solid collected, washed with petrol then taken up in ether. The ethereal solution was washed with water, dried (Na2SO4) and evaporated in vacuo to give ethyl 6,7-dimethyl-1,4-benzodioxan-2-carboxylate (10.17 g.), m.p. 70°-71° C. under reflux The addition procedure 4 hours under reflux for a further 33/4 hours After cooling the mixture was filtered the solids washed well with acetone the combined filtrate concentrated in vacuo Water (35 ml.) was added the resulting solid collected washed with petrol The ethereal solution was washed with water dried (Na2SO4) evaporated in vacuo