1,8-Diazabicyclo(5.4.0)undec-7-ene → phenylphosphonic acid 1-acetyl-1H-indazol-5-yl ester 4-nitrophenyl ester

Participants

Reaction Steps

A solution of 2.36 g of phenylphosphonic acid bis-(4-nitrophenyl) ester (prepared according to procedure E) in 60 ml of dichloromethane is cooled in an ice bath. 1.041 g of 1-(5-hydroxyindazol-1-yl)ethanone and 900 mg of 1,8-diazabicyclo[5.4.0]undec-7-ene in 40 ml of dichloromethane are added thereto and the reaction is continued at 20° C. for 2 hours. The reaction medium is washed with a saturated sodium bicarbonate solution until discoloration of the organic phase. After separation by settling out, the organic extracts are dried over magnesium sulfate and then evaporated under reduced pressure. 2.4 g of phenylphosphonic acid 1-acetyl-1H-indazol-5-yl ester 4-nitrophenyl ester are isolated, which compound is used without purification in the subsequent stage.

Provenance & Evidence