反应详情

To a solution of 5 g 5-(tert-Butyl-diphenyl-silanyloxymethyl)-2H-pyrazole-3-carboxylic acid ethyl ester in 10 ml DMF 4 g Cs2CO3 and 3 g 2-Bromo-N-(5-chloro-pyridin-2-yl)-acetamide were added and the mixture was stirred for 3 h. Then 10 ml of water were added and the mixture was extracted with ethyl acetate (2×50 ml). The combined organic layers were dried over MgSO4, filtered and concentrated under reduced pressure. Inspection of the TLC and HPLC/MS indicated that a 1:1 mixture of the desired product together with the regioisomeric 5-(tert-Butyl-diphenyl-silanyloxymethyl)-2-[(5-chloro-pyridin-2-ylcarbamoyl)-methyl]-2H-pyrazole-3-carboxylic acid ethyl ester was present. Purification of this mixture on silica gel eluting with a gradient on n-heptane/ethylacetate yielded the desired product as the faster eluting less polar isomer.

1. extractionthe mixture was extracted with ethyl acetate (2×50 ml)
2. dry with materialThe combined organic layers were dried over MgSO4
3. filtrationfiltered
4. concentrationconcentrated under reduced pressure
5. additionInspection of the TLC and HPLC/MS indicated that a 1:1 mixture of the desired product together with the regioisomeric 5-(tert-Butyl-diphenyl-silanyloxymethyl)-2-[(5-chloro-pyridin-2-ylcarbamoyl)-methyl]-2H-pyrazole-3-carboxylic acid ethyl ester
6. customPurification of this mixture on silica gel eluting with a gradient on n-heptane/ethylacetate