2-Methylbenzenesulfonic acid hydrate → (R)-2-acetamido-3-ethoxycarbonyl-2-penten-4-olide
Reaction equation
[NH2:1][C:2]1[C:3]([O:5][C@H:6]([CH3:13])[C:7]=1[C:8]([O:10][CH2:11][CH3:12])=[O:9])=[O:4].[OH2:14].[C:15]1([CH3:25])C(S(O)(=O)=O)=CC=CC=1>C(OC(=O)C)(=O)C>[C:15]([NH:1][C:2]1[C:3]([O:5][C@H:6]([CH3:13])[C:7]=1[C:8]([O:10][CH2:11][CH3:12])=[O:9])=[O:4])(=[O:14])[CH3:25]Participants
4
Reactant 2
Product 1
Reagents, catalysts & solvents 1
Conditions
- Temperature
- 40 °C
Procedure
12.04 g of (R)-2-amino-3-ethoxycarbonyl-2-penten-4-olide are dissolved in 48 ml of acetic anhydride, 125 mg of toluenesulphonic acid monohydrate are added and the whole is stirred overnight at 40° C. The mixture is concentrated by evaporation, dissolved in ethyl acetate and washed with water. The ethyl acetate is distilled off and the residue is recrystallised from ethyl acetate/cyclohexane, [α]D20 =+62.3° (3% in CHCl3), m.p. 119°-122° C.