Three-Component Synthesis of Highly Functionalized 5-Acetyloxazoles
作者:Tilman Lechel、Dieter Lentz、Hans-Ulrich Reissig
DOI:10.1002/chem.200900386
日期:2009.5.25
AbstractBy a flexible three‐component synthesis, alkoxy‐substituted enamides are easily available from lithiated alkoxyallenes, nitriles and carboxylic acids (see scheme). The treatment of these versatile intermediates with trifluoroacetic acid provided 5‐acetyloxazoles in moderate to good yields. Different substituents are possible at C‐2 and C‐5 and the 5‐acetyl group is a suitable handle for further synthetic transformations.magnified image
Synthesis of 5-Acetyloxazoles and 1,2-Diketones from β-Alkoxy-β-ketoenamides and Their Subsequent Transformations
作者:Tilman Lechel、Markus Gerhard、Daniel Trawny、Boris Brusilowskij、Luise Schefzig、Reinhold Zimmer、Jürgen P. Rabe、Dieter Lentz、Christoph A. Schalley、Hans-Ulrich Reissig
DOI:10.1002/chem.201100382
日期:2011.6.27
cyclized to 5‐acetyloxazole derivatives. The synthesis is very flexible with respect to the substitution pattern at C‐2 and C‐4 of the oxazole core. A mechanistic suggestion for the oxazole formation is presented on the basis of 18O‐labeled compounds and their mass spectrometric analysis. In several cases, 1,2‐diketones are formed as side products or even as major components. The acetyl moiety at C‐5 of the