Oxazoline is OK! A general and efficient method for the synthesis of oxazolines has been developed (see scheme). This allowed the preparation of 27 five‐membered‐ring heterocycles and 11 six‐membered‐ring heterocycles in moderate to good yields.
New octahedral ruthenium(II) complexes (1-4) have been synthesized from the reaction of ruthenium( II) precursors [RuHCl(CO)(EPh3)(3)] (E - P or As) with the bidentate Schiff base ligands, 2-((2,6-dimethylphenylimino) methyl) quinolin-8-ol (L-1) and 2-((2,6-diisopropylphenylimino) methyl) quinolin-8-ol (L-2) in ethanol. These complexes have been characterized by elemental analyses, IR, UV-Vis, H-1, C-13 and P-31 NMR and ESI-Mass spectroscopy. The molecular structure of the complex [RuCl(CO)(PPh3)(2)(L-2)] (2) was determined by single-crystal X-ray diffraction, which reveals a distorted octahedral geometry around ruthenium(II) ion. The catalytic activity of the new complexes was evaluated for the condensation of nitriles with ethanolamine under solvent free conditions. The processes were operative with aromatic and heteroaromatic nitriles and tolerated several substitutional groups. The studies on the effect of substitution over ligands, coligands, reaction time, temperature and catalyst loading were carried out in order to find the best catalyst in this series of complexes and favorable reaction conditions. A probable mechanism for the catalytic condensation of nitrile has also been proposed. The catalyst was recovered and recycled up to five times without significant loss of its activity. (C) 2015 Elsevier B.V. All rights reserved.
One-Step Conversion of Aldehydes to Oxazolines and 5,6-Dihydro-4<i>H</i>-1,3-oxazines Using 1,2- and 1,3-Azido Alcohols
作者:Jennifer G. Badiang、Jeffrey Aubé
DOI:10.1021/jo9521256
日期:1996.1.1
The reactions of 1,2- and 1,3-hydroxy azides with aldehydes under acidic conditions were examined. A variety of Lewis acids were examined, of which BF3 . OEt(2) was found the most convenient. Trimethylsilyl ether derivatives of the alcohols could also be reacted using trimethylsilyl triflate as the promoter. Twenty-five examples that proceed in moderate to quantitative yields are reported.