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Diamine Catalyzed Addition of ZnEt2 to PhC(O)CF3: Two Mechanisms and Autocatalytic Asymmetric Enhancement Calvillo Barahona, María de las Mercedes Casares González, Juan Ángel Cordovilla, Carlos Genov, Miroslav N. Martínez de Ilarduya Martínez de Ilarduya, Jesús María Espinet Rubio, Pablo Catalyst Producción Científica NMR studies of the catalytic addition reaction of ZnEt2 to PhC(O)CF3 in the presence of three very efficient catalysts [TMEDA, tBuBOX, and L; where L is a chiral diamine synthesized from optically pure (R,R)-1,2-diphenylethylenediamine and (S)-2,2'-bis-(bromomethyl)-1,1'-binaphthalene] reveal large differences in their behavior. For the ligands TMEDA and tBuBOX, the catalysis shows no unusual features and proceeds via [(N?N)Zn(Et){OC(CF3 )(Et)Ph}]. For N?N?L, the observation of autocatalytic asymmetric enhancement during the catalysis, and unusual inverse concentration dependence on the reaction rate, indicate the participation of an additional novel catalytic cycle that goes through a dinuclear intermediate containing one ZnEt2 and one ZnEt fragment connected by N?N and OR bridges. Interestingly, the (19) F NMR signals of the main product of the reaction ([Zn(Et){OC*(CF3 )(Et)Ph}]2 ) allowed us to assess the enantioselectivity of the processes in situ without the assistance of chiral chromatography. 2016-12-14T12:35:52Z 2016-12-14T12:35:52Z 2014 info:eu-repo/semantics/article Chemistry - A European Journal, 2014, vol. 20, Issue 45, p. 14800–14806 0947-6539 http://uvadoc.uva.es/handle/10324/21720 10.1002/chem.201403648 14800 14806 Chemistry - A European Journal eng info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by-nc-nd/4.0/ Attribution-NonCommercial-NoDerivatives 4.0 International Wiley SI