反应详情

A solution of 7.5 g of 2,3-dihydro-2-oxo-benzo[b]thiophen in 50 ml of hexamethylphosphoric acid triamide is added dropwise, with cooling, to a suspension of 2.4 g of a 50% sodium hydride/mineral oil dispersion in 100 ml of hexamethylphosphoric acid triamide, the temperature being kept below 15° during the addition. After stirring for half an hour at room temperature, 52 g of phenyl N-(2-thienyl)-carbamate, dissolved in 50 ml of hexamethylphosphoric acid triamide, are added dropwise, with external cooling. The reaction mixture is stirred for a further 16 hours at room temperature and is poured into a mixture of 200 ml of 2 N hydrochloric acid and 1000 ml of ice-water. An oil separates out and this crystallises after about 2 hours. The crystalline product, which contains solvent, is dissolved in 2 N sodium hydroxide solution and the solution is washed four times with ethyl acetate. The organic phase is washed with water, the aqueous phases are combined and acidified to a pH of 1 and the crude product is filtered off with suction and recrystallised from tetrahydrofuran/ether. N-(2-Thienyl)-2-oxo-2,3-dihydro-3-benzo[b]thiophen-carboxamide with a melting point of 142°-144° (decomposition) is obtained.

1. additionthe temperature being kept below 15° during the addition
2. additionare added dropwise, with external cooling
3. stirringThe reaction mixture is stirred for a further 16 hours at room temperature
4. customthis crystallises after about 2 hours
5. dissolutionis dissolved in 2 N sodium hydroxide solution
6. washthe solution is washed four times with ethyl acetate
7. washThe organic phase is washed with water
8. filtrationthe crude product is filtered off with suction
9. customrecrystallised from tetrahydrofuran/ether