Claims
- 1. A process for preparing a compound of the formula ##STR12## wherein: R.sub.1 is a readily removable carboxylic acid protecting group which is substantially unreactive toward ozone; and
- R.sub.2 is phthalimido or a group having the formula ##STR13## wherein: R.sub.3 is
- (1) hydrogen, C.sub.1 -C.sub.3 alkyl, halomethyl, benzyloxy, 4-nitrobenzyloxy tert.-butyloxy, 2,2,2-trichloroethoxy, 4-methoxybenzyloxy, 4-protected amino-4-protected carboxybutyl in which the amino protecting group and carboxy protecting group are substantially unreactive toward ozone; or
- (2) a group of the formula
- R.sub.4 --(O).sub.m --CH.sub.2 --
- wherein:
- m is 0 or 1; and
- R.sub.4 is phenyl or phenyl substituted with 1 or 2 halogens, nitro, cyano, trifluoromethyl, C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.2 alkoxy, protected hydroxy in which the hydroxy protecting group is substantially unreactive toward ozone; or
- (3) a group of the formula ##STR14## wherein: R.sub.4 is as defined above and
- W is protected hydroxy, protected carboxy, or protected amino in which the hydroxy protected group, the carboxy protecting group and the amino protecting group are substantially unreactive toward ozone;
- comprising the steps of reacting ozone with a compound of the formula ##STR15## in an unreactive solvent at a temperature ranging from -100 to about 0.degree. C. to form an intermediate ozonide, and reacting the ozonide with a mild reducing agent.
- 2. The process according to claim 1 wherein R.sub.1 is C.sub.4 -C.sub.6 tert. alkyl, benzyl, nitrobenzyl, methoxybenzyl, benzhydryl, phenacyl, phthalimidomethyl, or succinimidomethyl.
- 3. The process according to claim 2 wherein R.sub.2 is selected from phenoxyacetamido and phenylacetamido.
- 4. The process according to claim 1 wherein the reaction temperature is from about -80.degree. C. to 0.degree. C.
- 5. The process according to claim 4 wherein the unreactive reaction solvent is selected from halogenated hydrocarbons.
- 6. The process according to claim 5 wherein the mild reducing agent is selected from sodium bisulfite, sulfur dioxide, trimethyl phosphite, stannous chloride, zinc metal dust, Raney nickel, and dimethylsulfide.
- 7. The process according to claim 6, said process comprising reacting tert.butyl 7-phenoxyacetamido-3-bromomethyl-2-cephem-4-carboxylate with ozone at about 31 80.degree. C. in dichloromethane to form an intermediate ozonide, and decomposing the ozonide by reaction with sodium bisulfite to form 1-(1-tert. butyloxycarbonyl-2-hydroxy-3-bromo-1-propenyl)-3-phenoxyacetamido-4-formylthio-azetidin-2-one.
Parent Case Info
This is a division of application Ser. No. 626,946 filed Oct. 29, 1975, now U.S. Pat. No. 4,048,157.
Non-Patent Literature Citations (1)
Entry |
chauvette et al., J. Amer. Chem. Soc. 96, (15); 4986-4987 (1974). |
Divisions (1)
|
Number |
Date |
Country |
Parent |
626946 |
Oct 1975 |
|