反应详情

The resulting ethyl 1-(2-acetoxyethyl)pyrrole-2-glyoxalate prepared as in Preparation I (40.5 g, 0.16 mol.) is dissolved in anhydrous dichloromethane (900 ml.) and cooled to -70°. Recently distilled sulfuryl chloride (13.7 ml., 0.17 mol.) is added in a dropwise manner. When the addition is completed, the solution is allowed to come to room temperature spontaneously. After two hours at this temperature TLC (silica gel; hexane:ethyl acetate; 80:20) shows the absence of starting material. The solvent is removed in vacuo and the oily residue is dissolved in dichloromethane (300 ml.) and washed to neutrality with water. The organic phase is dried over sodium sulfate and evaporated to dryness in vacuo. The residue, which weighed 63 g. is purified by column chromatography on silica gel (800 g.) using hexane ethyl acetate (90:10) as the eluting solvent. This procedure yields 19 g. (41% yield) of ethyl 1-(2-acetoxyethyl)4-chloropyrrole-2-glyoxalate (Formula V where Y is Cl) having the following physical constants:

1. temperaturecooled to -70°
2. additionWhen the addition
3. customto come to room temperature
4. customThe solvent is removed in vacuo
5. dissolutionthe oily residue is dissolved in dichloromethane (300 ml.)
6. washwashed
7. dry with materialThe organic phase is dried over sodium sulfate
8. customevaporated to dryness in vacuo
9. customis purified by column chromatography on silica gel (800 g.)
10. customThis procedure yields 19 g