Structural Characterization of an Enantiomerically Pure Amino Acid Imidazolide and Direct Formation of the β-Lactam Nucleus from an α-Amino Acid
作者:Brian S. Gerstenberger、Jinzhen Lin、Yvette S. Mimieux、Lauren E. Brown、Allen G. Oliver、Joseph P. Konopelski
DOI:10.1021/ol7025922
日期:2008.2.1
Decomposition of a diazo beta-ketoamide derived from N-trityl serine imidazolide and N-protected acetanilides provides, instead of the expected beta-acyloxindole product, an enantiomerically pure (EP) beta-lactam. The amino acid stereocenter is incorporated, the second chiral center is induced, and trityl protection of the beta-lactam ring is realized for the first time. The desired beta-acyloxindole is obtained from oxindole and Tr-Ser(OBn)-imidazole, the X-ray of which provides the first structural determination of an EP amino acid imidazolide.
Enantiomerically Pure <i>trans</i>-β-Lactams from α-Amino Acids via Compact Fluorescent Light (CFL) Continuous-Flow Photolysis
作者:Yvette S. Mimieux Vaske、Maximillian E. Mahoney、Joseph P. Konopelski、David L. Rogow、William J. McDonald
DOI:10.1021/ja1050023
日期:2010.8.18
beta-lactams has been shown to vary from modest to nearly complete. An extremely facile, atom-economical method for the epimerization of the product mixture to the trans isomer, which is generally highly crystalline, has been developed. Evidence for C3 epimerization of Weinreb amide structures via a nonbasic, purely thermal route is presented. Subsequent transformations of both the Weinreb amide at C3 (beta-lactam