反应详情

A stirred suspension of sodium hydride (60% dispersion in oil [39 mg, 0.969 mmol]) in anhydrous tetrahydrofuran (10 ml) was treated with 1′-benzyl-5-chloro-1H-spiro[indole-3,3′-pyrrolidine]-2,2′,5′-trione, intermediate 14 (300 mg, 0.88 mmol). After stirring at ambient temperature for 30 min, the clear solution was treated with ethyl bromoacetate (0.13 ml, 1.16 mmol). The resultant suspension was stirred for 3 hours and then left to stand overnight. Water (50 ml) was added and the mixture extracted with ethyl acetate (3×50 ml). The combined extracts were washed with brine (50 ml), dried (MgSO4) and the solvent removed in vacuo to give the crude (1′-benzyl-5-chloro-2,2′,5′-trioxo-spiro[indole-3,3′-pyrrolidin]-1-yl)-acetic acid ethyl ester. Purification by flash chromatography (silica) eluting with petroleum ether (40-60) containing an increasing amount (0 to 50%) of ethyl acetate, followed by trituration with di-isopropyl ether gave a white solid (264 mg, 70%), m.pt. 143-144° C.

1. waitleft
2. waitto stand overnight
3. extractionthe mixture extracted with ethyl acetate (3×50 ml)
4. washThe combined extracts were washed with brine (50 ml)
5. dry with materialdried (MgSO4)
6. customthe solvent removed in vacuo
7. customto give the crude (1′-benzyl-5-chloro-2,2′,5′-trioxo-spiro[indole-3,3′-pyrrolidin]-1-yl)-acetic acid ethyl ester
8. customPurification by flash chromatography (silica)
9. washeluting with petroleum ether (40-60)
10. additioncontaining an increasing amount (0 to 50%) of ethyl acetate