Vancomycin atropisomerism

The most formidable challenge in the synthesis of vancomycin is to maintain control of the atropisomerism displayed as a result of hindered rotation of the aromatic residues in each of the three cyclic tripeptide units (AB, C-O-D, D-O-E see structure 111, Scheme 21). The Evans and Nicolaou procedures are similar in that each focuses first on construction of the... 

The Nicolaou group entered this area relatively recently, hence it is truly remarkable that they were able to develop a synthesis of the vancomycin aglycon so quickly. However, their route stumbles over the sections that involve atropisomeric selectivity or removal of the triazine. Evans group synthesis addresses or avoids these problems. It is a more polished effort that took many years and high levels of financial and human resources to develop. 

Structure of vancomycin. Vancomycin has three eiements of atropisomerism as indicated by three arrows... 

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