反应详情

A solution of 1'-(3,4-dichlorobenzyl)-spiro[imidazolidine-4,3'-indoline]-2,2',5-trione (3.76 g.) in dry N,N-dimethylformamide (50 ml.) was stirred during the addition of sodium hydride (0.50 g.) [50% w/w dispersion in oil]. When the addition was complete, the solution was stirred until effervescence had ceased (about 1 hour). Chloromethyl pivalate (1.55 g.) was then added. The mixture was stirred for 18 hours and then poured into water (200 ml.). The aqueous mixture was carefully acidified by addition of concentrated hydrochloric acid and the precipitated material has extracted with ethyl acetate (2×150 ml.). The combined extracts were washed with water (3×100 ml.) and then with brine (1×150 ml.), dried (MgSO4) and evaporated. The oil obtained was dissolved in ethyl acetate (100 ml.) and silica gel (10 g., type 7734 available from E. Merck Darmstadt, West Germany) was added. The mixture was evaporated and the residue was added to the top of a column of silica gel (150 g. Merck type 7734) made up in toluene. Elution with an increasing gradient of ethyl acetate in toluene with analysis by thin layer chromatography (SiO2 :50% ethyl acetate/toluene) of the fractions of eluate and combination and evaporation of those containing the major component (relative flow value: 0.6) gave 1'-(3,4-dichlorobenzyl)-1-pivaloyloxymethyl-spiro[imidazolidine-4,3'-indoline]-2,2',5-trione as a white solid (1.3 g.), m.p. 209°-211° C., after recrystallisation from a mixture of ethyl acetate and 60-80 petrol.

1. additionWhen the addition
2. custom(about 1 hour)
3. stirringThe mixture was stirred for 18 hours
4. extractionthe precipitated material has extracted with ethyl acetate (2×150 ml.)
5. washThe combined extracts were washed with water (3×100 ml.)
6. dry with materialwith brine (1×150 ml.), dried (MgSO4)
7. customevaporated
8. customThe oil obtained
9. additionsilica gel (10 g., type 7734 available from E. Merck Darmstadt, West Germany) was added
10. customThe mixture was evaporated
11. additionthe residue was added to the top of a column of silica gel (150 g. Merck type 7734)
12. washElution with an increasing gradient of ethyl acetate in toluene with analysis by thin layer chromatography (SiO2 :50% ethyl acetate/toluene) of the fractions of eluate and
13. customcombination and evaporation of those containing the major component (relative flow value: 0.6)