15875-74-8Relevant academic research and scientific papers
Transient imine as a directing group for the metal-free o-C-H borylation of benzaldehydes
Rej, Supriya,Chatani, Naoto
supporting information, p. 2920 - 2929 (2021/03/01)
Organoboron reagents are important synthetic intermediates and have wide applications in synthetic organic chemistry. The selective borylation strategies that are currently in use largely rely on the use of transition-metal catalysts. Hence, identifying much milder conditions for transition-metal-free borylation would be highly desirable. We herein present a unified strategy for the selective C-H borylation of electron-deficient benzaldehyde derivatives using a simple metal-free approach, utilizing an imine transient directing group. The strategy covers a wide spectrum of reactions and (i) even highly sterically hindered C-H bonds can be borylated smoothly, (ii) despite the presence of other potential directing groups, the reaction selectively occurs at the o-C-H bond of the benzaldehyde moiety, and (iii) natural products appended to benzaldehyde derivatives can also give the appropriate borylated products. Moreover, the efficacy of the protocol was confirmed by the fact that the reaction proceeds even in the presence of a series of external impurities.
Convenient fabrication of carbon doped WO3?x ultrathin nanosheets for photocatalytic aerobic oxidation of amines
Bao, Keyan,Zhang, Shaojie,Ni, Ping,Zhang, Zixiang,Zhang, Kailong,Wang, Liangbiao,Sun, Li Xia,Mao, Wutao,Zhou, Quanfa,Qian, Yitai
, p. 311 - 317 (2018/11/23)
It is an important chemical transformation for oxidation of amines to imines, on account of very important versatile applications of imines in organic synthesis. Here, we develop a convenient way to synthesize carbon doped WO3?x ultrathin nanos
2D sp2 Carbon-Conjugated Porphyrin Covalent Organic Framework for Cooperative Photocatalysis with TEMPO
Chen, Rufan,Hao, Huimin,Lang, Xianjun,Shi, Ji-Long,Wang, Cheng
supporting information, p. 9088 - 9093 (2020/03/30)
2D covalent organic frameworks (COFs) are receiving ongoing attention in semiconductor photocatalysis. Herein, we present a photocatalytic selective chemical transformation by combining sp2 carbon-conjugated porphyrin-based covalent organic framework (Por-sp2c-COF) photocatalysis with TEMPO catalysis illuminated by 623 nm red light-emitting diodes (LEDs). Highly selective conversion of amines into imines was swiftly afforded in minutes. Specifically, the π-conjugation of porphyrin linker leads to extensive absorption of red light; the sp2 ?C=C? double bonds linkage ensures the stability of Por-sp2c-COF under high concentrations of amine. Most importantly, we found that crystalline framework of Por-sp2c-COF is pivotal for cooperative photocatalysis with (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO). This work foreshadows that the outstanding hallmarks of COFs, particularly crystallinity, could be exploited to address energy and environmental challenges by cooperative photocatalysis.
Carbonylation Access to Phthalimides Using Self-Sufficient Directing Group and Nucleophile
Ji, Fanghua,Li, Jianxiao,Li, Xianwei,Guo, Wei,Wu, Wanqing,Jiang, Huanfeng
, p. 104 - 112 (2018/02/19)
Herein we report a novel palladium-catalyzed oxidative carbonylation reaction for the synthesis of phthalimides with high atom- and step-economy. In our strategy, the imine and H2O, which are generated in situ from the condensation of aldehyde and amine, serve as self-sufficient directing group and nucleophile, respectively. This method provides rapid access to phthalimides starting from readily available materials in a one-pot manner. Various phthalimide derivatives are constructed efficiently, including medicinally and biologically active phthalimide-containing compounds.
Structure-Reactivity Relationship in the Frustrated Lewis Pair (FLP)-Catalyzed Hydrogenation of Imines
Tussing, Sebastian,Kaupmees, Karl,Paradies, Jan
supporting information, p. 7422 - 7426 (2016/05/24)
The autoinduced, frustrated Lewis pair (FLP)-catalyzed hydrogenation of 16-benzene-ring substituted N-benzylidene-tert-butylamines with B(2,6-F2C6H3)3 and molecular hydrogen was investigated by kinetic analysis. The pKa values for imines and for the corresponding amines were determined by quantum-mechanical methods and provided a direct proportional relationship. The correlation of the two rate constants k1 (simple catalytic cycle) and k2 (autoinduced catalytic cycle) with pKa difference between imine and amine pairs (ΔpKa) or Hammett's σ parameter served as useful parameters to establish a structure-reactivity relationship for the FLP-catalyzed hydrogenation of imines.
Formal Ir-Catalyzed Ligand-Enabled Ortho and Meta Borylation of Aromatic Aldehydes via in Situ-Generated Imines
Bisht, Ranjana,Chattopadhyay, Buddhadeb
supporting information, p. 84 - 87 (2016/01/25)
The ligand-enabled development of ortho and meta C-H borylation of aromatic aldehydes is reported. It was envisaged that while ortho borylation could be achieved using tert-butylamine as the traceless protecting/directing group, meta borylation proceeds via an electrostatic interaction and a secondary interaction between the ligand of the catalyst and the substrate. These ligand-substrate electrostatic interactions and secondary B-N interactions provide an unprecedented controlling factor for meta-selective C-H activation/borylation.
Asymmetric induction in the addition of enantiomerically pure H-phosphinate to chiral aldimines: diastereoselective generation of α-amino phosphinates with P,C-stereogenic centers
Yang, Meng,Xu, Hao,Zhou, Zhong-Yang,Zhang, He,Liu, Li-Juan,Sun, Yong-Ming,Nie, Shao-Zhen,Zhao, Chang-Qiu
supporting information, p. 815 - 822 (2016/09/02)
α-Amino phosphinates with P,C-stereogenic centers were prepared from a P-retained addition of (RP)-(?)-menthyl H-phenylphosphinate to (R)-aldimines with up to 86:14 dr under catalyst and solvent free condition at ambient temperature; the single
Palladium-catalyzed synthesis of aldehydes from aryl halides and tert-butyl isocyanide using formate salts as hydride donors
Zhang, Ying,Jiang, Xiao,Wang, Jin-Mei,Chen, Jing-Lei,Zhu, Yong-Ming
, p. 17060 - 17063 (2015/03/30)
An efficient one-pot palladium-catalyzed hydroformylation of aryl halides to produce aromatic aldehydes has been achieved, employing tert-butyl isocyanide as a C1 resource and formate salt as a hydride donor without any additional bases. Characterized by its mild reaction conditions, easy operation and lower toxicity, this reaction can tolerate a wide array of functional groups with moderate to excellent yields.
New Heterocyclic Product Space for the Castagnoli-Cushman Three-Component Reaction
Dar'In, Dmitry,Bakulina, Olga,Chizhova, Maria,Krasavin, Mikhail
supporting information, p. 3930 - 3933 (2015/08/18)
Significant expansion of heterocyclic product space accessible by the Castagnoli-Cushman reaction (CCR) has been achieved via the use of glutaric anhydride analogues containing endocyclic substitutions with oxygen, nitrogen, and sulfur. Incorporation of these heteroatoms in the anhydride's backbone results in enhanced reactivity and generally lower temperatures that are required for the reactions to go to completion. These findings are particularly significant in light of the CCR recently recognized as an efficient tool for lead-oriented synthesis.
Regio- and Chemoselective Kumada-Tamao-Corriu Reaction of Aryl Alkyl Ethers Catalyzed by Chromium under Mild Conditions
Cong, Xuefeng,Tang, Huarong,Zeng, Xiaoming
supporting information, p. 14367 - 14372 (2015/12/01)
Acting as an environmentally benign synthetic tool, the cross-coupling reactions with aryl ethers via C-O bond activation have attracted broad interest. However, the functionalizations of C-O bonds are mainly limited to nickel catalysis, and selectivity has long been a prominent challenge when several C-O bonds are present in the one molecule. We report here the first chromium-catalyzed selective cross-coupling reactions of aryl ethers with Grignard reagents by the cleavage of C-O(alkyl) bonds. Diverse transformations were achieved using simple, inexpensive chromium(II) precatalyst combining imino auxiliary at room temperature. It offers a new avenue for buildup functionalized aromatic aldehydes with high efficiency and selectivity.
