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Solutions to Problems 473 33. (a) S CH₃ Most reactive Protein-NH₂ toward N nucleophiles 0 CH₃ COOH O S CH₃ Ring-opening relieves strain H-O N CH₃ NH COOH Protein C₆H₃CH₂CNH CH CH₃ C N CH₃ H Protein NH 0 COOH Penicilloyl protein (b) Formed via a parallel mechanism, with as the S CH CH₃ nucleophile. This product, penicilloic acid, no longer possesses the necessary strained azacyclobutanone ring for HOOC N CH₃ reaction with bacterial protein. It therefore lacks any H antibiotic properties. 34. Use the Lewis acids to activate the ring oxygen in (a) and (b). Hydrolysis (a) CH₂OH (A type of Friedel- Crafts reaction) BF₃⁻ + (b) Hydrolysis product OBF₄⁻ (c) Use the Lewis acid to activate the anhydride and form an acylium cation, similar to the first step in Friedel-Crafts alkanoylation. 0 + + and MgBr₂ CH,C 0 MgBr₂ MgBr + Br