2.1.2. Phenyl Esters. Phenyl esters were developed as a newclass of HsClpP inhibitors that aim to improve upon both drugpotency and chemical stability relative to β-lactones.38 Amongthe phenyl esters that were first developed to have showninhibition of HsClpP’s peptidase activity is AV-167 (Figure2D), which originates from a counter screen to identifypotential ClpP-inhibiting antibiotics against S. aureus