30915-38-9Relevant articles and documents
Hydrosilylation of Carbonyl Compounds Catalyzed through a Lithiated Hydrazone Derivative
Raya-Barón, álvaro,O?a-Burgos, Pascual,Rodríguez-Diéguez, Antonio,Fernández, Ignacio
, p. 2682 - 2689 (2018/09/10)
A well-defined lithiated hydrazone derivative has been synthesized and fully characterized through various analytical platforms, including multinuclear (1H, 13C, 15N, 7Li) and two-dimensional NMR, high-resolution MS spectrometry, IR, and X-ray diffraction crystallography. It behaves as a binuclear species in the solid state and as a monomeric contact ion pair in solution. It has also been tested as a catalyst in hydrosilylation reactions, being the first lithium hydrazone reported to catalyze the full conversion of carbonyls of different nature into alcohols in short reaction times, at room temperature, and with catalyst loadings equal to or below 0.5 mol %. Kinetic studies have proven fractional order dependences with respect to ketone and silane and first order dependence in the case of the catalyst. The proposed reaction mechanism is characterized by the nucleophilic addition of the lithium hydrazonide to the silicon atom of the silane to give a five-coordinate silicon species.
Kinetic Selectivity and Thermodynamic Features of Competitive Imine Formation in Dynamic Covalent Chemistry
Kulchat, Sirinan,Chaur, Manuel N.,Lehn, Jean-Marie
supporting information, p. 11108 - 11118 (2017/08/22)
The kinetic and thermodynamic selectivities of imine formation have been investigated for several dynamic covalent libraries of aldehydes and amines. Two systems were examined, involving the reaction of different types of primary amino groups (aliphatic amines, alkoxy-amines, hydrazides and hydrazines) with two types of aldehydes, sulfobenzaldehyde and pyridoxal phosphate in aqueous solution at different pD (5.0, 8.5, 11.4) on one hand, 2-pyridinecarboxaldehyde and salicylaldehyde in organic solvents on the other hand. The reactions were performed separately for given amine/aldehyde pairs as well as in competitive conditions between an aldehyde and a mixture of amines. In the latter case, the time evolution of the dynamic covalent libraries generated was followed, taking into consideration the operation of both kinetic and thermodynamic selectivities. The results showed that, in aqueous solution, the imine of the aliphatic amine was not stable, but oxime and hydrazone formed well in a pH dependent way. On the other hand, in organic solvents, the kinetic product was the imine derived from an aliphatic amine and the thermodynamic products were oxime and hydrazone. The insights gained from these experiments provide a basis for the implementation of imine formation in selective derivatization of mono-amines in mixtures as well as of polyfunctional compounds presenting different types of amino groups. They may in principle be extended to other dynamic covalent chemistry systems.
Adaptation in constitutional dynamic libraries and networks, switching between orthogonal metalloselection and photoselection processes
Vantomme, Ghislaine,Jiang, Shimei,Lehn, Jean-Marie
supporting information, p. 9509 - 9518 (2014/07/21)
Constitutional dynamic libraries of hydrazones aAbB and acylhydrazones aAcC undergo reorganization and adaptation in response to a chemical effector (metal cations) or a physical stimulus (light). The set of hydrazones [1A1B, 1A2B, 2A1B, 2A 2B] undergoes metalloselection on addition of zinc cations which drive the amplification of Zn(1A2B)2 by selection of the fittest component 1A2B. The set of acylhydrazones [E-1A1C, 1A2C, 2A1C, 2A2C] undergoes photoselection by irradiation of the system, which causes photoisomerization of E- 1A1C into Z-1A1C with amplification of the latter. The set of acyl hydrazones [E-1A1C, 1A3C, 2A1C, 2A 3C] undergoes a dual adaptation via component exchange and selection in response to two orthogonal external agents: a chemical effector, metal cations, and a physical stimulus, light irradiation. Metalloselection takes place on addition of zinc cations which drive the amplification of Zn( 1A3C)2 by selection of the fittest constituent 1A3C. Photoselection is obtained on irradiation of the acylhydrazones that leads to photoisomerization from E-1A 1C to Z-1A1C configuration with amplification of the latter. These changes may be represented by square constitutional dynamic networks that display up-regulation of the pairs of agonists ( 1A2B, 2A1B), (Z-1A 1C, 2A2C), (1A3C, 2A1C), (Z-1A1C, 2A 3C) and the simultaneous down-regulation of the pairs of antagonists (1A1B, 2A2B), (1A 2C, 2A1C), (E-1A1C, 2A3C), (1A3C, 2A 1C). The orthogonal dual adaptation undergone by the set of acylhydrazones amounts to a network switching process.
