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Tipo:	Artigo de Periódico
Título:	Asymmetric Transfer Hydrogenation of Aryl Heteroaryl Ketones and o-Hydroxyphenyl Ketones Using Noyori-Ikariya Catalysts
Autor(es):	Ye Zheng Jaime A. Martinez-Acosta Mohammed Khimji Luiz Cláudio de Almeida Barbosa Guy J. Clarkson Martin Wills
Resumen:	In 1995, Noyori and co-workers made a breakthrough with their design of practical ruthenium-based catalysts, which combined the homochiral TsDPEN ligand with a Ru(II) arene [1,2]. Using (R,R)-1 at a loading of 0.5 mol% in either KOH-iPrOH or the azeotropic mixture of formic acid–triethylamine (FA:TEA, 5:2 molar ratio), the reduction of acetophenone was achieved in up to 98% ee (Figure 1).The mechanism for the asymmetric transfer hydrogenation (ATH) with Noyori–Ikariya catalysts is now well-established (Figure 2) [3,4,5,6,7,8,9]. The precatalyst can be activated by elimination of HCl to form a 16-electron neutral Ru(II) complex. Then, the 16-electron complex abstracts two hydrogen atoms from the hydrogen donor, such as isopropanol, a formic acid/triethylamine (FA/TEA) mixture or sodium formate, to form a hydride that contains an 18-electron Ru(II) centre. Finally, the two hydrogen atoms are transferred to the C=O group and reduce ketone substrates into chiral alcohol products. Meanwhile, the 16-electron neutral Ru(II) complex is regenerated and can restart the catalytic cycle. The six-membered transition state can be stabilized by the combination of electrostatic interactions and steric effects. Edge/face (or CH/π) electrostatic interaction makes the electron-rich aryl group of a substrate favour the position adjacent to the η6-arene ring of the catalyst (Figure 3), whereas the large group and electron group favour the position distal to η6-arene ring (Figure 4).
Asunto:	Química Catálise Redução (Química) Hidrogenação
Idioma:	eng
País:	Brasil
Editor:	Universidade Federal de Minas Gerais
Sigla da Institución:	UFMG
Departamento:	ICEX - INSTITUTO DE CIÊNCIAS EXATAS ICX - DEPARTAMENTO DE QUÍMICA
Tipo de acceso:	Acesso Aberto
Identificador DOI:	https://doi.org/10.3390/ecsoc-25-11774
URI:	http://hdl.handle.net/1843/61104
Fecha del documento:	14-nov-2022
metadata.dc.url.externa:	http://https://doi.org/10.3390/ecsoc-25-11774
metadata.dc.relation.ispartof:	Chemistry Proceedings
Aparece en las colecciones:	Artigo de Periódico

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