Catalyzes the ring opening of 2,3-epoxy-2,3-dihydroxybenzoyl-CoA to form 3,4-didehydroadipyl-CoA semialdehyde. 2,3-epoxy-2,3-dihydrobenzoyl-CoA + 2 H2O = (3Z)-6-oxohex-3-enoyl-CoA + formate + H(+) The substrate was earlier believed to be 2,3-dihydro-2,3-dihydroxybenzoyl-CoA but it has later been shown to be the epoxide as the substrate was enzymatically produced by BoxAB. Optimum pH is 9. Homodimer. By benzoate. Belongs to the benzoyl-CoA oxygenase component C family.