Ligand Effect and Control of<i>E</i>- and<i>Z</i>-Selectivity in the Silver-Catalyzed Synthesis of 4-Bromooxazolines
作者:Valerie H. L. Wong、Andrew J. P. White、T. S. Andy Hor、King Kuok Mimi Hii
DOI:10.1002/adsc.201500157
日期:2015.8.10
The stereospecific intramolecular hydroamination of alkynyl trichloroacetimidates catalyzed by bis(pyridyl)silver(I) complexes to form 1,3‐oxazolines and oxazines has been investigated in greater detail. The rate of the reaction is profoundly influenced by the electronic character of the pyridyl ligand; leading to optimized conditions whereby reactions can be completed at ambient temperature with catalyst
Gold Catalysis: Alkylideneoxazolines and -oxazoles from Intramolecular Hydroamination of an Alkyne by a Trichloroacetimidate
作者:A. Stephen K. Hashmi、Matthias Rudolph、Stefan Schymura、Jorge Visus、Wolfgang Frey
DOI:10.1002/ejoc.200600572
日期:2006.11
be prevented which delivered the oxazoles after long reaction times. Up to 3333 turnovers could be reached. With gold(I) catalysts in chloroform or dichloromethane selective hydroamination to 4-methylene-4,5-dihydrooxazoles without subsequent aromatization was exclusively observed. The gold(I) catalysts also allowed chemoselective cycloisomerization of N-propargylcarboxamides to 5-methylene-4,5-dihydrooxazoles
[reaction: see text] A study on the gold (I)-catalyzedintramolecularhydroamination of trichloroacetimidates derived from propargyl and homopropargyl alcohols is described. In the presence of 2-5 mol % of cationic Au(I) complex, a variety of trichloroacetimidates undergo efficient hydroamination under an exceptionally mild condition. An orthogonality of the current catalytic protocol with those using
Silver-catalysed intramolecular hydroamination of alkynes with trichloroacetimidates
作者:Valerie H. L. Wong、T. S. Andy Hor、King Kuok (Mimi) Hii
DOI:10.1039/c3cc45500a
日期:——
Silver(I) complexes catalyse the intramolecular addition of trichloroacetimidates to alkynes. In the absence of a ligand, the selectivity of the reaction is dependent upon the nature of the counter-anion and solvent. The introduction of non-chelating nitrogeneous ligands suppresses competitive Brønsted acid catalysis, improving the yield and selectivity of the reaction.