Conformation changes induced in 2-spiro-substituted cephalosporin sulphoxides by the configuration of the spiro bond: A combined1H and13C NMR study
摘要:
Abstract1,3‐Dipolar cycloadditions of diazomethane and diphenyldiazomethane to exo‐2‐methylenecephalosporins are described. A structural study of the products shows that the initially formed 2‐spiropyrazolinocephems form cyclopropanes by the spontaneous loss of nitrogen. ASIS and NOE measurements reveal that the products with different C‐2 configurations are in two different conformations.