The azomethine ylide strategy for β-lactam synthesis. An evaluation of alternative pathways for azomethine ylide generation
作者:Giles A. Brown、Sarah R. Martel、Richard Wisedale、Jonathan P. H. Charmant、Neil J. Hales、Colin W. G. Fishwick、Timothy Gallagher
DOI:10.1039/b010050l
日期:——
been evaluated computationally. The data suggest that relief of strain within the four-membered ring—as opposed to 1 in which five-membered ring cleavage leads to an iminium ion—provides a driving force for C–S bond cleavage. As a result, the ability of 22 and 23 to give a synthetically useful azomethine ylide is compromised by the siting of an alternative leaving group adjacent to the azetidinone nitrogen