1962-08-9Relevant academic research and scientific papers
Zeolite-Encaged Isolated Platinum Ions Enable Heterolytic Dihydrogen Activation and Selective Hydrogenations
Dai, Weili,Deng, Xin,Guan, Naijia,Li, Landong,Liu, Runze,Ma, Ding,Qin, Bin,Qin, Xuetao,Wu, Guangjun
supporting information, p. 20898 - 20906 (2021/12/14)
Understanding the unique behaviors of atomically dispersed catalysts and the origin thereof is a challenging topic. Herein, we demonstrate a facile strategy to encapsulate Ptδ+ species within Y zeolite and reveal the nature of selective hydrogenation over a Pt@Y model catalyst. The unique configuration of Pt@Y, namely atomically dispersed Ptδ+ stabilized by the surrounding oxygen atoms of six-membered rings shared by sodalite cages and supercages, enables the exclusive heterolytic activation of dihydrogen over Ptδ+···O2- units, resembling the well-known classical Lewis pairs. The charged hydrogen species, i.e., H+ and Hδ-, are active reagents for selective hydrogenations, and therefore, the Pt@Y catalyst exhibits remarkable performance in the selective hydrogenation of α,β-unsaturated aldehydes to unsaturated alcohols and of nitroarenes to arylamines.
Synthesis of Tertiary Benzylic Nitriles via Nickel-Catalyzed Markovnikov Hydrocyanation of α-Substituted Styrenes
Xing, Yidan,Yu, Rongrong,Fang, Xianjie
supporting information, p. 1008 - 1012 (2020/02/04)
The Markovnikov hydrocyanation of α-substituted styrenes enables the synthesis of tertiary benzylic nitriles under nickel catalysis. The Lewis-acid-free transformation features an unprecedented functional groups tolerance, including the-OH and-NH2 groups. A broad range of tertiary benzylic nitriles were obtained in good to excellent yields. In addition, an asymmetric version of this reaction was preliminarily investigated.
Direct Electrophilic C?H Alkynylation of Unprotected 2-Vinylanilines
Caspers, Lucien D.,Finkbeiner, Peter,Nachtsheim, Boris J.
supporting information, p. 2748 - 2752 (2017/03/08)
Unprotected aromatic amines can be used as directing groups in metal-catalyzed C?H alkynylations of alkenes. By using low amounts of an IrIIIcatalyst in combination with alkynylbenziodoxolones as electrophilic alkyne-transfer reagents, highly desirable 1,3-enynes were isolated in excellent yields of up to 98 % with Z stereoselectivity. A broad substrate scope as well as the high synthetic utility of the 1,3-enynes render this new method an efficient approach for the synthesis of five- and six-membered heterocycles. Further derivatizations of the 1,3-enynes to highly substituted quinolines through AuI- and N-bromosuccinimide-mediated exo-dig cyclizations were demonstrated.
NH2-directed C-H alkenylation of 2-vinylanilines with vinylbenziodoxolones
Boelke, Andreas,Caspers, Lucien D.,Nachtsheim, Boris J.
supporting information, p. 5344 - 5347 (2017/11/07)
The first directing-group-mediated C-H alkenylation with alkenyl-λ3-iodanes as electrophilic alkene-transfer reagents has been developed. The application of free aromatic amines as challenging but synthetically valuable directing groups in combination with an IrIII catalyst enabled the synthesis of highly desirable 1, 3- dienes in excellent yields of up to 98% with high to perfect (Z, E) stereoselectivity. A broad substrate scope and further synthetic modifications are demonstrated.
Nickel-catalyzed amination of Aryl chlorides with ammonia or ammonium salts
Green, Rebecca A.,Hartwig, John F.
supporting information, p. 3768 - 3772 (2015/03/18)
The nickel-catalyzed amination of aryl chlorides to form primary arylamines occurs with ammonia or ammonium sulfate and a well-defined single-component nickel(0) precatalyst containing a Josiphos ligand and an η2-bound benzonitrile ligand. This system also catalyzes the coupling of aryl chlorides with gaseous amines in the form of their hydrochloride salts. Simple alternative: The title reaction, which results in primary arylamines, is catalyzed by well-defined single-component nickel(0) precatalysts containing a Josiphos ligand and an η2-bound benzonitrile ligand. This system also catalyzes the coupling of aryl chlorides with gaseous amines in the form of their hydrochloride salts.
Palladium-catalyzed amination of aryl chlorides and bromides with ammonium salts
Green, Rebecca A.,Hartwig, John F.
supporting information, p. 4388 - 4391 (2015/01/08)
We report the palladium-catalyzed coupling of aryl halides with ammonia and gaseous amines as their ammonium salts. The coupling of aryl chlorides and ortho-substituted aryl bromides with ammonium sulfate forms anilines with higher selectivity for the primary arylamine over the diarylamine than couplings with ammonia in dioxane. The resting state for the reactions of aryl chlorides is different from the resting state for the reactions of aryl bromides, and this change in resting states is proposed to account for a difference in selectivities for reactions of the two haloarenes.
A P,N-Ligand for palladium-catalyzed ammonia arylation: Coupling of deactivated aryl chlorides, chemoselective arylations, and room temperature reactions
Lundgren, Rylan J.,Peters, Brendan D.,Alsabeh, Pamela G.,Stradiotto, Mark
supporting information; experimental part, p. 4071 - 4074 (2010/07/05)
(Figure Presented) Amazing ammonia: A new air-stable P,N-ligand (Mor-DalPhos) is reported that enables the palladium-catalyzed crosscoupling of ammonia to a variety of aryl chloride and aryl tosylate substrates with high chemoselectivity and, for the first time, at room temperature (see scheme; Ad = adamantyl, Ts=para-toluenesulfonyl).
