Chiral bisoxazolidine

This asymmetric carbene reaction has been extended successfully, but in an unexpected direction [37]. Thus, as illustrated in Scheme 10, the cyclopropane synthesis is now used for the industrial synthesis of Cilastatin (36), which acts as an excellent in vivo stabilizer of the antibiotic Imipenem (37) (Merck Co., USA, and Sumitomo Chemical Co. Ltd., Japan). Chiral bisoxazolidine-Cu complexes (Structures 38 and 39) also exhibit high efficiency in asymmetric cyclopropanation [38]. 

Palladium/silver-catalyzed Heck reactions have usually involved vinyl or aryl halides and alkenes, but these reaction conditions were also extended to allenes. Indeed, Zenner and Larock65 showed that simple alkyl allenes readily reacted with aryl and vinyl iodide derivatives in the presence of palladium acetate or chloride and silver phosphate. Moreover, the reaction could be rendered asymmetric using chiral ligands the best one was a bisoxazolidine derivative (Scheme 10.37). 

Scheme 18 Chiral Mg-bisoxazolidine complex-catalyzed intramolecular redox reactions via [1,5]-HT/cyclization...

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