217 5. UiS MONOBACTAMES OH ·•' H N +rCH3 3 - H CIC02tBu BOC-NÀ~:•: 'e H , 0 0 0 OH L-Thréonine BOC-L-Thréonine 7 OH BOC-N~,CH3 CIS02CH3 , _ -oc, N H Base 0 H 10a (SN,) H 1 CH3 . BOC-N)=t: (S) ~ (S) H " O OCH3 14 15