反应详情

7.66 g (37.9 mmol) of 4-bromo-3-methoxy-phenylamine (preparation described in Tetrahedron Lett., 1995, 7583) were dissolved in 80 ml of cyclohexane at 70° C. and subsequently treated under stirring with 72 mg (0.38 mmol) of p-toluenesulfonic acid monohydrate and 4.93 g (37.9 mmol) of ethyl acetoacetate. The solution was then heated at reflux for 3.5 h with a water separator funnel connected. It was then cooled to RT and concentrated in vacuo. The residue was applied to a silica gel column with hexane/diethyl ether (3:1) as eluent. Combinations of the purified fractions and concentration in vacuo gave 8.2 g (68.8%) of the (Z)-3-(4-bromo-3-methoxy-phenylamino)-but-2-enoic acid ethyl ester, as a yellow solid. ISP mass spectrum, m/e: 316.2(M+1 calculated for C13H16BrNO3: 316).

1. additionsubsequently treated
2. temperatureThe solution was then heated
3. concentrationconcentrated in vacuo
4. concentrationCombinations of the purified fractions and concentration in vacuo