16176-22-0Relevant academic research and scientific papers
Catalytic Asymmetric Synthesis of Alkynyl Aziridines: Both Enantiomers of cis-Aziridines from One Enantiomer of the Catalyst
Guan, Yong,L?pez-Alberca, Maria P.,Lu, Zhenjie,Zhang, Yu,Desai, Aman A.,Patwardhan, Aniruddha P.,Dai, Yijing,Vetticatt, Mathew J.,Wulff, William D.
, p. 13894 - 13900 (2014)
Alkynyl aziridines can be obtained from the catalytic asymmetric aziridination (AZ reaction) of alkynyl imines with diazo compounds in high yields and high asymmetric inductions mediated by a chiral boroxinate or BOROX catalyst. In contrast to the AZ reaction with aryl- and alkyl-substituted imines, alkynyl imines react to give cis-substituted aziridines with both diazo esters and diazo acetamides. Remarkably, however, the two diazo compounds give different enantiomers of the cis-aziridine from the same enantiomer of the catalyst. Theoretical considerations of the possible transition states for the enantiogenic step reveal that the switch in enantiomers results from a switch from Si-face to Re-face addition to the imine, which in turn is related to a switch from reaction with an E-imine in the former and a Z-isomer of the imine in the latter. The imine did it: The aziridination of alkynyl imines with diazo esters and diazo acetamides gives cis-aziridines with very high enantioselectivities. The absolute configuration of the cis-aziridine is reversed for the two diazo compounds even though the same enantiomer of the catalyst is used. The alkynyl imines can isomerize under the reaction conditions and the enantiomeric switch is proposed to result from the preferential reaction of E-imine with diazo esters and Z-imines with diazo acetamides.
Transition-metal-free and facile synthesis of 3-alkynylpyrrole-2,4-dicarboxylates from methylene isocyanides and propiolaldehyde
Huo, Xiaoli,Chen, Xiaojuan,Yu, Liya,Zhang, Chong,Zeng, Linghui,Zhu, Huajian,Shao, Jiaan,Fu, Liping,Zhang, Jiankang
supporting information, p. 16430 - 16433 (2021/10/01)
A transition-metal-free, facile and efficient method for the synthesis of 3-alkynylpyrrole-2,4-dicarboxylates from methylene isocyanides and propiolaldehyde with moderate to good yields has been developed. The direct transformation process and good tolerance of various substituents make it an alternative approach to previous protocols, and potential applications of these investigated compounds are expected with or without post-modifications.
Photocatalyzed Diastereoselective Isomerization of Cinnamyl Chlorides to Cyclopropanes
Dykstra, Ryan,Gutierrez, Osvaldo,Martin, Robert T.,Tambar, Uttam K.,Troian-Gautier, Ludovic,Xu, Bin
supporting information, p. 6206 - 6215 (2020/04/27)
Endergonic isomerizations are thermodynamically unfavored processes that are difficult to realize under thermal conditions. We report a photocatalytic and diastereoselective isomerization of acyclic cinnamyl chlorides to strained cyclopropanes. Quantum mechanical calculations (uM06-2X and DLPNO), including TD-DFT calculations, and experimental studies provide evidence for the energy transfer from an iridium photocatalyst to the allylic chloride substrate followed by C-Cl homolytic cleavage. Subsequent Cla￠ radical migration forms a localized triplet 1,3-diradical intermediate that, after intersystem crossing, undergoes ring-closing to form the desired product. The mild reaction conditions are compatible with a broad range of functional groups to generate chlorocyclopropanes in high yields and diastereoselectivities. A more efficient process is developed by addition of a catalytic amount of a nickel complex, and we propose a novel role for this cocatalyst to recycle an allyl chloride byproduct generated in the course of the reaction. The reaction is also shown to be stereoconvergent, as an E/Z mixture of cinnamyl chlorides furnish the anti-chlorocyclopropane product in high diastereoselectivity. We anticipate that the use of a visible light activated photocatalyst to transform substrates in combination with a transition metal catalyst to recycle byproducts back into the catalytic cycle will provide unique opportunities for the discovery of new reactivity.
Development of a telescoped flow process for the safe and effective generation of propargylic amines
Donnelly, Kian,Zhang, Huan,Baumann, Marcus
, (2019/11/02)
Propargylic amines are important multifunctional building blocks that are frequently exploited in the synthesis of privileged heterocyclic entities. Herein we report on a novel flow process that achieves the safe and effective on-demand synthesis of propargylic amines in a telescoped manner. This process minimizes exposure to hazardous azide intermediates and renders a streamlined route into these building blocks. The value of this approach is demonstrated by the rapid generation of a small selection of drug-like thiazolines that result from a high-yielding reaction cascade between propargylic amines with different aryl isothiocyanates.
Magnetic covalent hybrid of graphitic carbon nitride and graphene oxide as an efficient catalyst support for immobilization of Pd nanoparticles
Sadjadi, Samahe,Malmir, Masoumeh,Heravi, Majid M.,Ghoreyshi Kahangi, Fatemeh
, p. 62 - 70 (2019/01/15)
For the first time a magnetic carbon based hybrid catalyst, Pd@g-C3N4-Fe-GO, is prepared through covalent conjugation of magnetic graphitic carbon nitride and graphene oxide followed by incorporation of Pd nanoparticles. First, the formation of the catalyst was confirmed via XRD, TG, BET, TEM, FTIR, ICP and VSM analyses and then its catalytic activity for promoting Suzuki and Sonogashira coupling reactions under mild reaction condition was investigated. To elucidate whether hybridization of two carbon materials could improve the catalytic activity, the catalytic activity of the catalyst was compared with the control catalysts (Pd@g-C3N4 -GO, Pd@g-C3N4-Fe, Pd@ Fe-GO, Pd@g-C3N4, Pd@GO and the GO/g-C3N4 physical hybrid). Moreover, the role of magnetic nanoparticles in the catalytic performance was confirmed. Notably, the catalytic activities of the catalyst and the control sample prepared via physical hybridization of two carbon materials were compared to confirm the effect of covalent conjugation on the catalytic activity. Moreover, the study of the substituent effect of p-substituted phenyl iodides was considered by Hammett plot, which revealed a beneficial effect of electron-withdrawing side groups for the C–C coupling reaction. Finally, the recyclability of Pd@g-C3N4-Fe-GO as well as leaching of Pd and magnetic nanoparticles was studied.
Pd(0) nanoparticles immobilized on multinitrogen functionalized halloysite for promoting Sonogashira reaction: studying the role of the number of surface nitrogens in catalytic performance
Sadjadi, Samahe,Heravi, Majid M.,Masoumi, Baharak,Kazemi, Shaghayegh Sadat
, p. 119 - 134 (2019/01/30)
Halloysite nanoclay, Hal, was amine-functionalized and subsequently reacted with 2,4,6-trichloro-1,3,5-triazine, TCT, and ethylenediamine, EDA, to provide multinitrogen containing functionality on the surface of Hal. The resulting surface-modified Hal, Ha
Pd@GO/Fe3O4/PAA/DCA: a novel magnetic heterogeneous catalyst for promoting the Sonogashira cross-coupling reaction
Daraie, Mansoureh,Heravi, Majid M.,Kazemi, Shaghayegh Sadat
, p. 2279 - 2293 (2019/08/07)
A hybrid system involving graphene oxide (GO), magnetic oxide (Fe3O4), acrylamide and dicyandiamide was prepared via amine functionalization of GO/Fe3O4 by means of covalent bonding with acrylamide and subsequent reaction with dicyandiamide to provide a multinitrogen containing polymer on the surface of GO. This hybrid system was utilized as a heterogeneous catalyst support for immobilizing Pd nanoparticles to provide the hybrid, Pd@GO/Fe3O4/PAA/DCA. This nano-Pd composite was characterized using Fourier transform infrared, transmission electron microscopy, scanning electron microscopy, vibrating sample magnetometer, thermogravimetric analysis, X-ray diffraction, and ICP techniques and used for promoting Sonogashira cross-coupling under mild reaction conditions. This heterogeneous and magnetic catalyst was easily separated by external magnet and was reused in a model reaction, efficiently up to six times with slight loss of catalytic activity and Pd leaching, showing the suitability of GO/Fe3O4/PAA/DCA for embedding Pd nanoparticles. To check the effect of the number of surface nitrogens of the polymeric chain on the catalytic performance, the activity of the catalyst was compared with Pd@GO/Fe3O4/PAA; increased number of the surface nitrogens on the chain polymer leads to higher loading of Pd and lower the Pd leaching.
Halloysite nanoclay decorated with 2-amino pyrimidine functionalized poly glycidyl methacrylate: An efficient support for the immobilization of Pd nanoparticles
Sadjadi, Samahe,Koohestani, Fatemeh,Bahri-Laleh, Naeimeh,Didehban, Khadijeh
, p. 59 - 66 (2019/01/08)
Taking advantage of the synergistic effects between polymer (P) and halloysite clay (Hal) as well as the capability of heteroatom-containing polymers for anchoring nanoparticles and suppressing their leaching, a novel support composed of Hal and 2-amino p
Catalytic Generation and Chemoselective Transfer of Nucleophilic Hydrides from Dihydrogen
Pape, Felix,Brechmann, Lea T.,Teichert, Johannes F.
supporting information, p. 985 - 988 (2019/01/04)
Copper(I)–N-heterocyclic-carbene (NHC) complexes enabled the catalytic generation of nucleophilic hydrides from dihydrogen (H2) and their subsequent transfer to allylic chlorides. The highly chemoselective catalyst displayed no concomitant hydrogenation reactivity; in fact, the terminal double bond formed in the hydride transfer remained intact. Switching to deuterium gas (D2) allowed for regioselective monodeuteration with excellent isotope incorporation.
Catalyst-Free Annulation of 2-Pyridylacetates and Ynals with Molecular Oxygen: An Access to 3-Acylated Indolizines
Chen, Zhengwang,Liang, Pei,Ma, Xiaoyue,Luo, Haiqing,Xu, Guohai,Liu, Tanggao,Wen, Xiaowei,Zheng, Jing,Ye, Hui
supporting information, p. 1630 - 1639 (2019/01/26)
A catalyst and additive-free annulation of 2-pyridylacetates and ynals under molecular oxygen was the first developed, affording 3-acylated indolizines in good to excellent yields. Molecular oxygen was used as the source of the carbonyl oxygen atom in indolizines. This approach was compatible with a wide range of functional groups, and especially it has been successfully extended to unsaturated double bonds and triple bonds, which were difficult to prepare by previous methods in a single step.
