CHEM 346 PROBLEM SET 3 Due 2 9 12 Please complete the following problems You may work either in groups or on your own The answer key will be posted on RamCT on the due date 1 Bruice Ch 16 problems 49 52 75 76 81 NOTE For 81 the stereocenter in the product is drawn incorrectly It should be inverted 2 Bruice Ch 17 problems 11 35 52 3 Rank the following molecules in order of increasing reactivity to nucleophiles O O F3C Cl Ph O O N H O O NO2 O O O Cl 4 Nucleophilic substitution reactions of the following isomeric tosylates shown below exhibit several remarkable features As expected reaction of the cis compound proceeds with inversion of configuration at the carbon undergoing substitution Substitution of the trans compound however proceeds cleanly with retention of configuration and this reaction occurs 700 times faster than the reaction of the cis isomer Provide stepwise mechanisms for each of these reactions which are consistent with these results For a hint look at question 5 OTs OAc OTs OAc NaOAc AcOH k1 NaOAc AcOH k2 OAc OAc OAc OAc k2 k1 700 O O S Ts Ac O CH3 CH3 5 When the trans isomer is heated in ethanol a different product is formed Provide a mechanism for the formation of this product OTs OAc EtOH heat O O CH3 OEt 6 Amoxicillin is a clinically valuable penicillin derivative that kills bacteria by inhibiting cell wall biosynthesis Its key feature is a lactam which is attacked by a hydroxyl group in the active site of a transpeptidase enzyme Speculate why this reaction is easier than one would expect for simple amides HO amoxicillin NH2 O H N O S H N Me Me CO2H OH transpeptidase enzyme