86129-99-9Relevant academic research and scientific papers
Trio catalysis merging enamine, br?nsted acid, and metal lewis acid catalysis: Asymmetric three-component aza-diels-alder reaction of substituted cinnamaldehydes, cyclic ketones, and arylamines
Deng, Yongming,Kumar, Siddhartha,Wheeler, Kraig,Wang, Hong
, p. 7874 - 7880 (2015)
A trio catalyst system, composed of arylamine, BINOL-derived phosphoric acid, and Y(OTf)3, enables the combination of enamine catalysis with both hard metal Lewis acid catalysis and Br?nsted acid catalysis for the first time. Using this catalyst system, a three-component aza-Diels-Alder reaction of substituted cinnamaldehyde, cyclic ketone, and arylamine is carried out with high chemo- and enantioselectivity, affording a series of optically active 1,4-dihydropyridine (DHP) derivatives are obtained in 91-99 % ee and 59-84 % yield. DHPs bearing a chiral quaternary carbon center are also obtained with good enantioselectivity and moderate yield (three examples). Preliminary mechanistic investigations have also been conducted.
Stabilized Ru[(H2O)6]3+ in Confined Spaces (MOFs and Zeolites) Catalyzes the Imination of Primary Alcohols under Atmospheric Conditions with Wide Scope
Mon, Marta,Adam, Rosa,Ferrando-Soria, Jesús,Corma, Avelino,Armentano, Donatella,Pardo, Emilio,Leyva-Pérez, Antonio
, p. 10401 - 10406 (2018/10/24)
Imines are ubiquitous intermediates in organic synthesis, and the metal-mediated imination of alcohols is one of the most direct and simple methods for their synthesis. However, reported protocols lack compatibility with many other functional groups since basic supports/media, pure oxygen atmospheres, and/or released hydrogen gas are required during reaction. Here we show that, in contrast to previous metal-catalyzed methods, hexa-aqueous Ru(III) catalyzes the imination of primary alcohols with very wide functional group tolerance, at slightly acid pH and under low oxygen atmospheres. The inorganic metal complex can be supported and stabilized, integrally, within either faujasite-type zeolites (Y and X) or a metal organic framework (MOF), to give a reusable heterogeneous catalyst which provides an industrially viable process well below the flammability limit of alcohols and amines.
Understanding α,β-unsaturated imine formation from amine additions to α,β-unsaturated aldehydes and ketones: An analytical and theoretical investigation
Calow, Adam D. J.,Carbó, Jorge J.,Cid, Jessica,Fernández, Elena,Whiting, Andrew
supporting information, p. 5163 - 5172 (2014/06/23)
A combination of in situ IR spectroscopy (ReactIR) and DFT calculations have been used to understand what factors govern the selectivity in the addition of primary amines to α,β-unsaturated aldehydes and ketones, i.e., 1,2- versus 1,4-addition. It has been found that the 1,2-addition products (α,β-unsaturated imines following addition and elimination) usually predominate for most systems. However, exceptions, such as methyl vinyl ketone, selectively give 1,4-addition products. This has been rationalized by DFT calculations that show that major conformational effects are involved, controlled mainly by steric effects of carbonyl substituents, resulting in a model that provides simple and predictable preparation of α,β- unsaturated imines for in situ utilization in synthesis.
A bifunctional PdVMgO solid catalyst for the one-pot selective N-monoalkylation of amines with alcohols
Corma, Avelino,Rodenas, Tania,Sabater, Maria J.
supporting information; experimental part, p. 254 - 260 (2010/03/26)
It has been found that a bifunctional metal Pd/base (MgO) catalyst performs the selective monoalkylation of amines with alcohols. The reaction goes through a series of consecutive steps in a cascade mode that involves: 1) the abstraction of hydrogen from the alcohol that produces the metal hydride and the carbonyl compound; 2) condensation of the carbonyl with the amine to give an imine, and 3) hydrogenation of the imine with the surface hydrogen atoms from the metal hydride. Based on isotopic and spectroscopic studies and on the rate of each elementary step, a global reaction mechanism has been proposed. The controlling step of the process is the hydride transfer from the metal to the imine. By changing the crystallite size of the Pd, it is demonstrated that this is a structure-sensitive reaction, whereas the competing processes that lead to subproducts are not. On these bases, a highly selective catalyst has been obtained with Pd crystallite size below 2.5 nm in diameter. The high efficiency of the catalytic system has allowed us to extend the process to the one-pot synthesis of piperazines.
One - Pot Reformatsky-Imine addition reaction-leading to the synthesis of structurally diverse β-lactams
Rajput, Jaspreet,Singh, Baldev,Singal, Kewal Krishan
, p. 643 - 648 (2008/09/18)
The Reformatsky-imine addition reaction of a-bromoethylacetate with aldimines derived from 3,4-methylenedioxy benzaldehyde and α- methylcinnamaldehyde has provided an efficient and practical access to structurally diverse β-lactams. All the new β-lactams
Halogenated Ketenes. 38. Cycloaddition of α,β-Unsaturated Imines with Ketenes To Yield Both β- and δ-Lactams
Brady, William T.,Shieh, C. H.
, p. 2499 - 2502 (2007/10/02)
The cycloaddition of various types of α,β-unsaturated imines with diphenyl- and dichloroketenes yields both (2 + 2) and (4 + 2) cycloaddition products, i. e., β-lactams and δ-lactams, respectively.The cycloaddition products are dependent upon substitution in the imine and the ketene.The δ-lactams derived from dichloroketene are easily dehydrochlorinated to the corresponding 2-pyridones.All of the results are consistent with a two-step cycloaddition process involving a dipolar intermediate.
