Cephem compounds

1. A compound of the formula:

wherein

A is lower alkylene or lower alkenylene;

R 1 is lower alkyl, hydroxy(lower)alkyl, protected hydroxy(lower)alkyl in which the hydroxy group is protected with an acyl group or an aryl(lower)alkyl group, amino(lower)alkyl or an amino(lower)alkyl in which the amino group is protected by an acyl group or a substituted or unsubstituted aryl(lower)alkyl group, and

R 2 is hydrogen or an amino protecting group selected from the group consisting of an acyl group or a substituted or unsubstituted aryl(lower)alkyl group, or

R 1 and R 2 are bonded together and form lower alkylene;

R 3 and R 5 are, independently, amino or amino protected with an acyl group or a substituted or unsubstituted aryl(lower)alkyl group; and

R 4 is carboxy or esterified carboxy,

or a pharmaceutically acceptable salt thereof.

2. The compound of claim 1 wherein

R 1 is lower alkyl, hydroxy(lower)alkyl, aryl(lower)alkyloxy(lower)alkyl, amino(lower)alkyl or acylamino(lower)alkyl, and

R 2 is hydrogen, aryl(lower)alkyl or acyl, or

R 1 and R 2 are bonded together and form lower alkylene;

R 3 and R 5 are, independently, amino or acylamino; and

R 4 is carboxy or esterified carboxy,

or a pharmaceutically acceptable salt thereof.

3. The compound of claim 2 wherein

R 1 is lower alkyl, hydroxy(lower)alkyl, aryl(lower)alkyloxy(lower)alkyl, amino(lower)alkyl, (lower)alkanoylamino(lower)alkyl, or (lower)alkoxycarbonylamino(lower)alkyl, and

R 2 is hydrogen, aryl(lower)alkyl, lower alkanoyl or lower alkoxycarbonyl, or

R 1 and R 2 are bonded together and form lower alkylene;

R 3 and R 5 are, independently, amino, lower alkanoylamino or lower alkoxycarbonylamino; and

R 4 is carboxy or lower alkoxycarbonyl,

or a pharmaceutically acceptable salt thereof.

4. The compound of claim 3 wherein

R 1 is lower alkyl, hydroxy(lower)alkyl or amino(lower)alkyl, and

R 2 is hydrogen, or

R 1 and R 2 are bonded together and form lower alkylene;

R 3 and R 5 are amino; and

R 4 is carboxy,

or a pharmaceutically acceptable salt thereof.

5. A process for preparing a compound of the formula [I]:

wherein

A is lower alkylene or lower alkenylene;

R 1 is lower alkyl, hydroxy(lower)alkyl, protected hydroxy(lower)alkyl in which the hydroxyl group is protected with an acyl group or an aryl(lower)alkyl group, amino(lower)alkyl or an amino(lower)alkyl in which the amino group is protected by an acyl group or a substituted or unsubstituted aryl(lower)alkyl group, and

R 2 is hydrogen or an amino protecting group selected from the group consisting of an acyl group or a substituted or unsubstituted aryl(lower)alkyl group, or

R 1 and R 2 are bonded together and form lower alkylene;

R 3 and R 5 are, independently, amino or amino protected with an acyl group or a substituted or unsubstituted aryl(lower)alkyl group; and

R 4 is carboxy or esterified carboxy,

or a salt thereof, which comprises

(1) reacting a compound of the formula [II]:

wherein A, R 1 , R 2 and R 3 are each as defined above, or its reactive derivative at the amino group, or a salt thereof with a compound of the formula [III]:

wherein R 4 and R 5 are each as defined above, or its reactive derivative at the carboxy group, or a salt thereof to give a compound of the formula [I]:

wherein A, R 1 , R 2 , R 3 , R 4 and R 5 are each as defined above, or a salt thereof, or

(2) subjecting a compound of the formula [Ia]:

wherein A, R 1 , R 2 , R 4 and R 5 are each as defined above, and R 3 a an amino group protected by an acyl group or a substituted or unsubstituted aryl(lower)alkyl group, or a salt thereof to elimination reaction of the amino protecting group to give a compound of the formula [Ib]:

wherein A, R 1 , R 2 , R 4 and R 5 are each as defined above, or a salt thereof, or

(3) reacting a compound of the formula [VI]:

wherein R 4 R 5 are each as defined above, R 6 is an esterfied carboxy group, and Y is a leaving group, or a salt thereof with a compound of the formula [VII]:

wherein A, R 1 , R 2 , and R 3 are each as defined above, or a salt thereof to give a compound of the formula [VIII]:

wherein A, R 1 , R 2 , R 3 , R 4 , R 5 , and R 6 are each as defined above, or a salt thereof, and

subjecting the compound of the formula [VIII] or a salt thereof to elimination reaction of the carboxy protecting group, to give a compound of the formula [I]:

wherein A, R 1 , R 2 , R 3 , R 4 , and R 5 are each as defined above, or a salt thereof.

6. A pharmaceutical composition, comprising a compound of claim 1 or a pharmaceutically acceptable salt thereof in admixture with a pharmaceutically acceptable carrier.

7. A method of making the pharmaceutical composition of claim 6 , comprising combining the compound or a pharmaceutically acceptable salt thereof with the pharmaceutically acceptable carrier.

8. A method of treating an infectious disease caused by a bacterium, comprising administering an effective amount of the compound of claim 1 or a pharmaceutically acceptable salt thereof to a human being or a non-human animal.

9. The method of claim 8 , wherein the compound or the pharmaceutically acceptable salt thereof is administered to a human being.

10. A method of treating an infectious disease caused by a bacterium, comprising administering an effective amount of the pharmaceutical composition of claim 6 to a human being or a non-human animal.

11. The method of claim 10 , wherein the pharmaceutical composition is administered to a human being.