反应详情

A solution of the ester product of Step B above (4.5 g., 8.7 mmole) and pyridinium tosylate (220 mg., 0.87 mmole) in ethanol (50 ml.) is let stand at 25° C. for 2.5 hours. To this reaction solution is added a solution of sodium hydroxide (1.2 g., 30 mmole) in water (12 ml.). The resulting soluton is let stand at 25° C. for 20 hours. The ethanol is then evaporated at reduced pressure. The residue is dissolved in water, and the solution acidified with 2 N hydrochloric acid to precipitate the product as a yellow gum. It is chromatographed on 60 g. of silica gel with elution by 2% methanol in chloroform. The purified title product is obtained as a yellowish, viscous oil weighing 2.4 g.; pmr (CDCl3) δ2.74 (2H, brt, CH2Ph), 3.55 (2H, brs, COCH2S), 4.70 (1H, brd, SCHN), 5.70 (2H, m, CH=CH), 6.53 (2H, brs, OH and CO2H).

1. customThe ethanol is then evaporated at reduced pressure
2. dissolutionThe residue is dissolved in water
3. customto precipitate the product as a yellow gum
4. customIt is chromatographed on 60 g
5. washof silica gel with elution by 2% methanol in chloroform
6. customThe purified title product
7. customis obtained as a yellowish, viscous oil