2-bromoethyl butanoate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 6,7-Methylenedioxy-3-(4-hydroxyphenyl)-4H-1-benzopyran-4-one [cp. Nippon Kagaku Zasshi 85, 793 (1964), Agr. Biol. Chem. (Tokyo) 32, 740 (1968) and Angew. Chem. 93, 129 (1981)] (2.0 g) is dissolved in dimethylformamide (15 ml) and K2CO3 (2.8 g) is added to the solution. While stirring, 2-bromoethylbutyrate (2.7 g) is dropped into the mixture. The content of the reaction flask is refluxed for 30 min. After cooling, water (50 ml) is added and the mixture is extracted with chloroform (3×30 ml), the extract washed with water (3×15 ml) and dried over Na2SO4. Chloroform is removed under reduced pressure and the residue is recrystallized from methanol. The product is dried in vacuo to constant weight to yield 6,7-methylenedioxy-3-[4-(1-ethoxycarbonyl-1-propyloxy)-phenyl]-4H-1-benzopyran-4-one, m.p. 119°-121°. The content of the reaction flask is refluxed for 30 min After cooling the mixture is extracted with chloroform (3×30 ml) the extract washed with water (3×15 ml) dried over Na2SO4 Chloroform is removed under reduced pressure the residue is recrystallized from methanol The product is dried in vacuo to constant weight