反应详情

温度

100 °C

2.50 g of 3-hydroxy-2-methoxy-3-{4-[2-(5-methyl-2-phenyl-oxazol-4-yl)-ethoxy]-benzo[b]thiophen-7-yl}-propionic acid methyl ester (5.25 mmol, syn/anti mixture of 1:4) was dissolved at room temperature in 25 ml of DMF. After the addition of 0.59 ml of conc. sufuric acid (10.5 mmol), the brown solution was stirred at 100° C. for 15 h. During cooling the reaction solution to r.t., the product crystallized. Under stirring, 15 ml of methanol were added at r.t. and the suspension stirred for 1 h at 0° C. The white crystals were filtered off, washed with 25 ml of cold (−15° C.) methanol in two portions and dried to constant weight (20° C./5 mbar/16 h) to afford 2.13 g (90%) of the title compound with a purity of 99.5% (GC area).

1. temperatureDuring cooling the reaction solution to r.t.
2. customthe product crystallized
3. stirringUnder stirring
4. addition15 ml of methanol were added at r.t.
5. stirringthe suspension stirred for 1 h at 0° C
6. filtrationThe white crystals were filtered off
7. washwashed with 25 ml of cold (−15° C.) methanol in two portions
8. customdried to constant weight (20° C./5 mbar/16 h)