反应详情

Thionyl chloride (3.9 g, 0.033 mole) was added to a stirred mixture of 5,6-dihydro-2-methyl-1,4-oxathiin-3-carboxylic acid (5.2 g, 0.032 mole) and methylene chloride (100 ml). The mixture was stirred overnight at room temperature, then evaporated under reduced pressure. The residue, crude 5,6-dihydro-2-methyl-1,4-oxathiin-3-carbonyl chloride, was dissolved in methylene chloride (100 ml), and the ice-chilled solution treated dropwise with a solution of pentyl 5-amino-2-chlorobenzoate (7.9 g, 0.033 mole) and triethylamine (3.3 g, 0.033 mole) in methylene chloride (100 ml). The reaction mixture was stirred at room temperature for 4 hours, then worked up by washing in sequence with water, dilute hydrochloric acid, water, 2% sodium hydroxide and water. Evaporation of the solvent left an oil, which solidified very slowly. After recrystallization from ethanol (30 ml) the product 5.9 g, 47% yield) melted at 65°-68° C. A second recrystallization raised the melting point to 70°-71° C.

1. customevaporated under reduced pressure
2. dissolutionThe residue, crude 5,6-dihydro-2-methyl-1,4-oxathiin-3-carbonyl chloride, was dissolved in methylene chloride (100 ml)
3. temperaturethe ice-chilled solution
4. stirringThe reaction mixture was stirred at room temperature for 4 hours
5. washby washing in sequence with water, dilute hydrochloric acid, water, 2% sodium hydroxide and water
6. customEvaporation of the solvent
7. waitleft an oil, which