Norcardicin synthesis

Nonapeptide hnear amides are also often synthesized using the carbodiimide method. Examples include the synthesis of norcardicine A and the synthesis of renin inhibitors. The total synthesis of a trifluoromethyl (Tfm) analogue of pepstatin uses EDCCl/HOBt in the condensation steps. ... 

The importance of j -lactams in the penicillins , cephalosporins , thienamycin and the recent discovery of antibiotic activity among monocyclic j -lactams such as norcardicins or the )5-lactamase inhibitor clavulanic acid have recently intensified research toward the synthesis of this system . Among the different procedures that have been developed for incorporating a 2-azetidinone unit , the ring expansion of cyclopropanol amines provides a simple and convenient route to these attractive small ring compounds. 

N-Alkylation of P-lactams has been carried out using PTC (Scheme 18). This is an important step in the synthesis of norcardicin. 

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