反应详情

A solution of 200 mg of 3-(p-nitrophenylsulfonyl)-7,7-dimethoxybicyclo[3.2.0]hept-2-en-2-carboxylic acid, diphenylmethyl ester, in 5 mL of methylene chloride was diluted with 20 mL of acetic acid. Aqueous hydrochloric acid (4N, 3 mL) was added, the mixture was stirred for 1 hr at room temperature, and then evaporated to dryness at 25°. The residue was partitioned between methylene chloride and water and the organic layer was washed with brine, dried (Na2SO4), and evaporated. The residue was dissolved in a small amount of 5% methanol in methylene chloride and treated with an excess of diphenyldiazomethane to esterify any free acid present. After nitrogen evolution ceased, the reaction mixture was evaporated to dryness and the residue was dissolved in methylene chloride-ether to give a solution from which precipitated 127 mg (69.3%) of 3-(p-nitrophenylsulfonyl)-7-oxobicyclo[3.2.0]hept-2-en-2-carboxylic acid, diphenyl methyl ester, as colorless crystals. IR (Nujol mull): 1730, 1780 cm-1 ; NMR (80 MHz; CDCl3): δ 2.5-3.6 (5H, m), 4.7 (1H, m), 7.0 (1H, s), 7.2-7.5 (10H, m), 8.0 (2H, d, J=9), and 8.23 (2H, d, J=9). ##STR26##

1. customevaporated to dryness at 25°
2. customThe residue was partitioned between methylene chloride and water
3. washthe organic layer was washed with brine
4. dry with materialdried (Na2SO4)
5. customevaporated
6. dissolutionThe residue was dissolved in a small amount of 5% methanol in methylene chloride
7. additiontreated with an excess of diphenyldiazomethane
8. customthe reaction mixture was evaporated to dryness
9. dissolutionthe residue was dissolved in methylene chloride-ether
10. customto give a solution from which
11. customprecipitated 127 mg (69.3%) of 3-(p-nitrophenylsulfonyl)-7-oxobicyclo[3.2.0]hept-2-en-2-carboxylic acid, diphenyl methyl ester