An Efficient [2 + 2 + 1] Synthesis of 2,5-Disubstituted Oxazoles via Gold-Catalyzed Intermolecular Alkyne Oxidation
作者:Weimin He、Chaoqun Li、Liming Zhang
DOI:10.1021/ja2029188
日期:2011.6.8
reaction of gold carbene intermediates generated via gold-catalyzed alkyne oxidation has been realized using nitriles as both the reacting partner and the reaction solvent, offering a generally efficient synthesis of 2,5-disubstituted oxazoles with broad substrate scope. The overall reaction is a [2 + 2 + 1] annulation of a terminal alkyne, a nitrile, and an oxygen atom from an oxidant. The reaction conditions
Calcined MgAICO<sub>3</sub>-HT Catalysed Cyanosilylation of Carbonyl Compounds and Nucleophilic Ring Opening of Oxiranes Using TMSCN
作者:B. M. Choudary、N. Narender、V. Bhuma
DOI:10.1080/00397919508011830
日期:1995.9
Nucleophilic addition of TMSCN to carbonyl compounds is found to be catalysed efficiently using hydrotalcite as a solid base. The catalyst is also found to be active in the nucleophilicringopening of oxiranes giving high regioselectivity.
coordination of different metal ions at enantiotopic positions of an achiral meso‐ligand are reported. These catalysts exhibit a pseudo‐Cs symmetry and are able to catalyze reactions demanding simultaneous involvement of two catalytic sites. The latter was demonstrated by application in the asymmetric ring‐opening of meso‐epoxides.
Chiral Ti(IV) complexes of hexadentate Schiff bases as precatalysts for the asymmetric addition of TMSCN to aldehydes and the ring opening of cyclohexene oxide
作者:Yuri N. Belokon、Denis Chusov、Dmitry A. Borkin、Lidia V. Yashkina、Andrey V. Dmitriev、Dmitry Katayev、Michael North
DOI:10.1016/j.tetasy.2006.08.009
日期:2006.9
Chiral dinuclear titanium(IV) complexes (generated in situ from hexadentate Schiffbases and titanium tetra-isopropoxide) have been found to be more effective catalysts for the asymmetric addition of trimethylsilyl cyanide to aldehydes and the ring opening of cyclohexene oxide than their mononuclear analogues. The best results were obtained for benzaldehyde (86% enantiomeric excess) and cyclohexene
Epoxides can be opened under neutral conditions with TMSN3 and TMSCN in the presence of catalytic amounts of Lewis acid, affording the corresponding ring-opened compounds in high yields.