How many chiral centers does clavulanic acid have?

Clavulanic acid has two (2) chiral centers.

Explanation:

A chiral center is a center (usually carbon) with four different substituents.

The structure of clavulanic acid is shown in the attachment below.

Consider the labeled diagram in the attachment,

Carbon A is not a chiral carbon because it has two hydrogen atoms attached to it

Carbon B is not a chiral carbon because it has only three substituents

Carbon C is a chiral carbon because it has four different substituents

Carbon D is a chiral carbon because it has four different substituents

Carbon E is not a chiral carbon because it has only three atoms directly attached to it

Carbon F is not a chiral carbon because it has only three atoms directly attached to it

Carbon G is not a chiral carbon because it has two hydrogen atoms attached to it

Carbon H is not a chiral carbon because it has only three substituents

Then, only carbons C and D are chiral carbons.

Hence, clavulanic acid have two (2) chiral centers.