Hydrochloric Acid → Hydrochloric Acid

Participants

Reaction Steps

12.15 g of (6R,7R)-7-amino-3-(5-methyl-2H-tetrazol-2-yl)-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene- 2-carboxylic acid are suspended in 60 ml of acetone. The suspension is treated within 15 minutes at 20°-25° while stirring with 6.3 g of 1.8-diazabicyclo[5.4.0]undec-7-ene (DBU), 10.6 g of pivaloyloxymethyl iodide are added to the resulting solution at 15° and the mixture is stirred for 15 minutes without cooling. 250 ml of n-butyl acetate are now added thereto. Crystallized-out DBU hydroiodide is filtered off under suction and washed with 50 ml of n-butyl acetate. The yellow filtrate is washed twice with 125 ml of saturated sodium chloride solution each time and filtered through a fluted filter. 100 ml of solvent are distilled off in a water-jet vacuum at 35°. The solution is again filtered and treated while stirring with 8.4 g of p-toluenesulphonic acid . H2O. The crystallized-out material is filtered off under suction after stirring for 30 minutes and washed with n-butyl acetate. The material obtained is suspended in 200 ml of n-butyl acetate and treated while stirring with 20 ml of 5.2N hydrochloric acid in isopropanol, whereby a solution results. This solution is stirred for 1 hour, whereby crystallization occurs. The crystallized-out hydrochloride is filtered off under suction, washed with n-butyl acetate and n-hexane and dried overnight in a water-jet vacuum at 35°. There are obtained 13.9 g (77.75%) of methylene (6R,7R)-7-amino-3-[5-methyl-2H-tetrazol-2-yl)methyl]-8-oxo-5-thia-1azabicyclo[4.2.0]oct-2-ene-2-carboxylate pivalate hydrochloride as white crystals (C16H22N6O5S. HCl; MW: 446.91).

Provenance & Evidence