734548-24-4Relevant academic research and scientific papers
Evidence for an enol mechanism in a highly enantioselective Mannich-type reaction catalyzed by primary amine-thiourea
Yalalov, Denis A.,Tsogoeva, Svetlana B.,Shubina, Tatyana E.,Martynova, Irina M.,Clark, Timothy
supporting information; experimental part, p. 6624 - 6628 (2009/03/12)
(Chemical Equation Presented) A tale of two mechanisms - enol versus enamine: Chiral primary amine-thiourea 1 catalyzes highly enantioselective Mannich-type addition of unmodified ketones to N-benzoylhydrazones (see scheme). The reaction does not require
Catalytic asymmetric Mannich-type reactions activated by ZnF2 chiral diamine in aqueous media
Hamada, Tomoaki,Manabe, Kei,Kobayashi, Shu
, p. 1205 - 1215 (2007/10/03)
Catalytic asymmetric Mannich-type reactions of an α-hydrazono ester with silicon enolates in aqueous media have been developed by using ZnF 2 and chiral diamines as catalysts. In these reactions, both Zn 2+ and a fluoride anion were necessary to achieve high yields and enantioselectivities. suggesting a double activation mechanism, in which Zn 2+ activates the α-hydrazono ester and the fluoride anion simultaneously activates the silicon enolate. When chiral diamine ligands bearing methoxy-substituted aromatic rings were employed, the reactions in aqueous THF were markedly accelerated. Furthermore, the use of these diamines facilitated the asymmetric Mannich-type reactions in water without any organic cosolvents. It is noteworthy that either syn or anti adducts were stereospecifically obtained from (E) or (Z)-silicon enolates, respectively. Interestingly, these reactions proceeded smoothly only in the presence of water. On the basis of several experimental results, it can be concluded that the reaction mechanism is likely to be a fluoride-catalyzed one, in which the ZnF2 chiral diamine complex is regenerated from the Me3SiF formed during the reaction.
Enantio- and diastereoselective, stereospecific Mannich-type reactions in water
Hamada, Tomoaki,Manabe, Kei,Kobayashi, Shu
, p. 7768 - 7769 (2007/10/03)
Catalytic asymmetric Mannich-type reactions in water proceeded in high yields and selectivities using a combination of ZnF2 and a chiral diamine that has the methoxy groups on the aromatic rings. In these reactions, either syn- or anti-Mannich
