Reaction #55421

Reaction equation

7-amino-3-[1-(2-carbamoylethyl)tetrazol-5-ylthiomethyl]-3-cephem-4-carboxylic acid

O-t-butyldiisopropylpseudourea

→

7-amino-3-[1-(2-carbamoylethyl)tetrazol-5-ylthiomethyl]-3-cephem-4-carboxylic acid t-butyl ester

Solvents

methylene chloride

methylene chloride

Conditions

Workup

1. 1
   workup.ADDITIONTo a suspension of 19.3 g
2. 2
   OtherThe precipitate is removed by filtration
3. 3
   Otherthe filtrate is evaporated
4. 4
   Otherto give a residue which
5. 5
   Filtrationof benzene and filtered again
6. 6
   ExtractionThe filtrate is extracted with three 100 ml
7. 7
   workup.ADDITIONthe pH is adjusted to 7.5 by addition of solid sodium bicarbonate
8. 8
   OtherThe organic layer is separated
9. 9
   Extractionthe aqueous phase is extracted with two 150 ml
10. 10
    DryingThe combined extracts are dried (MgSO4)
11. 11
    Filtrationfiltered
12. 12
    Otherevaporated to dryness

Procedure

To a suspension of 19.3 g. (0.05 mol.) of 7-amino-3-[1-(2-carbamoylethyl)tetrazol-5-ylthiomethyl]-3-cephem-4-carboxylic acid in 500 ml. of dry methylene chloride is added in one portion 30.0 g. (0.15 mol.) of O-t-butyldiisopropylpseudourea in 50 ml. of methylene chloride and the mixture is stirred at ambient temperature for 24 hours. The precipitate is removed by filtration and the filtrate is evaporated to give a residue which is taken up in 200 ml. of benzene and filtered again. The filtrate is extracted with three 100 ml. portions of cold 1N hydrochloric acid. The aqueous extracts are layered with ethyl acetate and the pH is adjusted to 7.5 by addition of solid sodium bicarbonate. The organic layer is separated and the aqueous phase is extracted with two 150 ml. portions of ethyl acetate. The combined extracts are dried (MgSO4), filtered and evaporated to dryness to give 7-amino-3-[1-(2-carbamoylethyl)tetrazol-5-ylthiomethyl]-3-cephem-4-carboxylic acid t-butyl ester.

Source