1608460-63-4Relevant academic research and scientific papers
Mechanism of the TiIII-Catalyzed Acyloin-Type Umpolung: A Catalyst-Controlled Radical Reaction
Streuff, Jan,Feurer, Markus,Frey, Georg,Steffani, Alberto,Kacprzak, Sylwia,Weweler, Jens,Leijendekker, Leonardus H.,Kratzert, Daniel,Plattner, Dietmar A.
, p. 14396 - 14405 (2015)
The titanium(III)-catalyzed cross-coupling between ketones and nitriles provides an efficient stereoselective synthesis of α-hydroxyketones. A detailed mechanistic investigation of this reaction is presented, which involves a combination of several methods such as EPR, ESI-MS, X-ray, in situ IR kinetics, and DFT calculations. Our findings reveal that C-C bond formation is turnover-limiting and occurs by a catalyst-controlled radical combination involving two titanium(III) species. The resting state is identified as a cationic titanocene-nitrile complex and the beneficial effect of added Et3N·HCl on yield and enantioselectivity is elucidated: chloride coordination initiates the radical coupling. The results are fundamental for the understanding of titanium(III)-catalysis and of relevance for other metal-catalyzed radical reactions. Our conclusions might apply to a number of reductive coupling reactions for which conventional mechanisms were proposed before.
The cross-selective titanium(III)-catalysed acyloin reaction
Feurer, Markus,Frey, Georg,Luu, Hieu-Trinh,Kratzert, Daniel,Streuff, Jan
supporting information, p. 5370 - 5372 (2014/05/06)
A titanium(iii)-catalysed intermolecular reductive coupling of ketones or imines with nitriles is described, which gives direct access to α-hydroxylated and α-aminated ketones. This coupling reaction is cross-selective and a catalytic version of the classical acyloin condensation. A reaction mechanism that is supported by first DFT calculations is discussed. the Partner Organisations 2014.
