39830-55-2Relevant academic research and scientific papers
Bismuth(iii)-catalyzed regioselective alkylation of tetrahydroquinolines and indolines towards the synthesis of bioactive core-biaryl oxindoles and CYP19 inhibitors
Prusty, Namrata,Kinthada, Lakshmana K.,Meena, Rohit,Chebolu, Rajesh,Ravikumar, Ponneri Chandrababu
, p. 891 - 905 (2021/02/09)
Bismuth(iii)-catalyzed regioselective functionalization at the C-6 position of tetrahydroquinolines and the C-5 position of indolines has been demonstrated. For the first time, one pot symmetrical and unsymmetrical arylation of isatins with tetrahydroquinolines was accomplished giving a completely new product skeleton in good to excellent yields. Most importantly, this protocol leads to the formation of a highly strained quaternary carbon stereogenic center, which is a challenging task. Benzhydryl and 1-phenylethyl trichloroacetimidates have been used as the alkylating partners to functionalize the C-6 and C-5 positions of tetrahydroquinolines and indolines, respectively. The scope of the developed methodology has been extended for the synthesis of the bioactive CYP19-inhibitor and its analogue.
Site-Selective Silylation of Arenes Mediated by Thianthrene S-Oxide
Wu, Yichen,Huang, Yu-Hao,Chen, Xiao-Yue,Wang, Peng
supporting information, p. 6657 - 6661 (2020/09/02)
The thianthrene S-oxide (TTSO)-mediated site-selective silylation of arenes has been realized via a thianthrenation/Pd-catalyzed silylation sequence. This method features a broad substrate scope and wide functional group tolerance under mild conditions and allows the synthesis of a set of (hetero)arylsilanes with operationally simple manipulations. The application and generality of the approach were further demonstrated by the late-stage functionalization of marketed drugs. This reaction also represents the first example of a Pd-catalyzed silylation reaction of aryl sulfonium salts.
B(C6F5)3-Catalyzed Highly Chemoselective Reduction of Isatins: Synthesis of Indolin-3-ones and Indolines
Jeong, Hyojin,Han, Nara,Hwang, Dong Wook,Ko, Haye Min
, p. 8150 - 8155 (2020/11/02)
A chemo- and site-selective reduction reaction of isatin derivatives using catalyst B(C6F5)3 and hydrosilanes is described. This transformation is operationally simple, proceeds under mild conditions, and is resistant to various functional groups. Thus, this efficient reaction using a combination of B(C6F5)3 and BnMe2SiH or B(C6F5)3 and Et2SiH2 could potentially be utilized to produce various indolin-3-ones and indolines, without the need for multistep procedures and metal catalysis conditions.
Ir-Catalyzed Reversible Acceptorless Dehydrogenation/Hydrogenation of N-Substituted and Unsubstituted Heterocycles Enabled by a Polymer-Cross-Linking Bisphosphine
Zhang, Deliang,Iwai, Tomohiro,Sawamura, Masaya
supporting information, p. 5240 - 5245 (2020/07/03)
The polystyrene-cross-linking bisphosphine ligand PS-DPPBz was effective for the Ir-catalyzed reversible acceptorless dehydrogenation/hydrogenation of N-heterocycles. Notably, this protocol is applicable to the dehydrogenation of N-substituted indoline derivatives with various N-substituents with different electronic and steric natures. A reaction pathway involving oxidative addition of an N-adjacent C(sp3)-H bond to a bisphosphine-coordinated Ir(I) center is proposed for the dehydrogenation of N-substituted substrates.
Ligand-Promoted Non-Directed C?H Cyanation of Arenes
Liu, Luo-Yan,Yeung, Kap-Sun,Yu, Jin-Quan
supporting information, p. 2199 - 2202 (2019/01/24)
This article reports the first example of a 2-pyridone accelerated non-directed C?H cyanation with an arene as the limiting reagent. This protocol is compatible with a broad scope of arenes, including advanced intermediates, drug molecules, and natural products. A kinetic isotope experiment (kH/kD=4.40) indicates that the C?H bond cleavage is the rate-limiting step. Also, the reaction is readily scalable, further showcasing the synthetic utility of this method.
Dehydrogenation of N-Heterocycles by Superoxide Ion Generated through Single-Electron Transfer
Huang, Yuan-Qiong,Song, Hong-Jian,Liu, Yu-Xiu,Wang, Qing-Min
supporting information, p. 2065 - 2069 (2018/01/27)
Nitrogen-containing heteroarene motifs are found in numerous pharmaceuticals, natural products, and synthetic materials. Although several elegant methods for synthesis of these compounds through dehydrogenation of the corresponding saturated heterocycles have been reported, some of the methods are hampered by long reaction times, harsh conditions, and the need for catalysts that are not readily available. This work reports a novel method for dehydrogenation of N-heterocycles. Specifically, O2.? generated in situ acts as the oxidant for N-heterocycle substrates that are susceptible to oxidation through a hydrogen atom transfer mechanism. This method provides a general, green route to N-heteroarenes.
Transfer Hydrogenation of Alkenes Using Ethanol Catalyzed by a NCP Pincer Iridium Complex: Scope and Mechanism
Wang, Yulei,Huang, Zhidao,Leng, Xuebing,Zhu, Huping,Liu, Guixia,Huang, Zheng
supporting information, p. 4417 - 4429 (2018/04/05)
The first general catalytic approach to effecting transfer hydrogenation (TH) of unactivated alkenes using ethanol as the hydrogen source is described. A new NCP-type pincer iridium complex (BQ-NCOP)IrHCl containing a rigid benzoquinoline backbone has been developed for efficient, mild TH of unactivated C-C multiple bonds with ethanol, forming ethyl acetate as the sole byproduct. A wide variety of alkenes, including multisubstituted alkyl alkenes, aryl alkenes, and heteroatom-substituted alkenes, as well as O- or N-containing heteroarenes and internal alkynes, are suitable substrates. Importantly, the (BQ-NCOP)Ir/EtOH system exhibits high chemoselectivity for alkene hydrogenation in the presence of reactive functional groups, such as ketones and carboxylic acids. Furthermore, the reaction with C2D5OD provides a convenient route to deuterium-labeled compounds. Detailed kinetic and mechanistic studies have revealed that monosubstituted alkenes (e.g., 1-octene, styrene) and multisubstituted alkenes (e.g., cyclooctene (COE)) exhibit fundamental mechanistic difference. The OH group of ethanol displays a normal kinetic isotope effect (KIE) in the reaction of styrene, but a substantial inverse KIE in the case of COE. The catalysis of styrene or 1-octene with relatively strong binding affinity to the Ir(I) center has (BQ-NCOP)IrI(alkene) adduct as an off-cycle catalyst resting state, and the rate law shows a positive order in EtOH, inverse first-order in styrene, and first-order in the catalyst. In contrast, the catalysis of COE has an off-cycle catalyst resting state of (BQ-NCOP)IrIII(H)[O(Et)···HO(Et)···HOEt] that features a six-membered iridacycle consisting of two hydrogen-bonds between one EtO ligand and two EtOH molecules, one of which is coordinated to the Ir(III) center. The rate law shows a negative order in EtOH, zeroth-order in COE, and first-order in the catalyst. The observed inverse KIE corresponds to an inverse equilibrium isotope effect for the pre-equilibrium formation of (BQ-NCOP)IrIII(H)(OEt) from the catalyst resting state via ethanol dissociation. Regardless of the substrate, ethanol dehydrogenation is the slow segment of the catalytic cycle, while alkene hydrogenation occurs readily following the rate-determining step, that is, β-hydride elimination of (BQ-NCOP)Ir(H)(OEt) to form (BQ-NCOP)Ir(H)2 and acetaldehyde. The latter is effectively converted to innocent ethyl acetate under the catalytic conditions, thus avoiding the catalyst poisoning via iridium-mediated decarbonylation of acetaldehyde.
One-Pot Sulfonamide Synthesis Exploiting the Palladium-Catalyzed Sulfination of Aryl Iodides
Flegeau, Emmanuel Ferrer,Harrison, Jack M.,Willis, Michael C.
supporting information, p. 101 - 105 (2015/12/26)
Aryl ammonium sulfinates, conveniently prepared from aryl iodides and the sulfur dioxide surrogate DABSO, under the action of a palladium(0) catalyst, are transformed in a one-pot process to a variety of functionalized sulfonamides. The sulfinate to sulfonamide transformation is achieved by simple treatment with an aqueous solution of the relevant amine and sodium hypochlorite (bleach). A broad range of amines, including anilines, and amino acid derivatives, are combined efficiently with a variety of aryl iodides, leading to sulfonamides in high yields.
Selenium-catalyzed oxidative c(sp2)-h amination of alkenes exemplified in the expedient synthesis of (Aza-)indoles
Ortgies, Stefan,Breder, Alexander
supporting information, p. 2748 - 2751 (2015/06/16)
A new selenium-catalyzed protocol for the direct, intramolecular amination of C(sp2)-H bonds using N-fluorobenzenesulfonimide as the terminal oxidant is reported. This method enables the facile formation of a broad range of diversely functionalized indoles and azaindoles derived from easily accessible ortho-vinyl anilines and vinylated aminopyridines, respectively. The procedure exploits the pronounced carbophilicity of selenium electrophiles for the catalytic activation of alkenes and leads to the formation of C(sp2)-N bonds in high yields and with excellent functional group tolerance.
Palladium-catalyzed C-7 alkenylation of indolines using molecular oxygen as the sole oxidant
Yang, Dong,Mao, Shuai,Gao, Ya-Ru,Guo, Dong-Dong,Guo, Shi-Huan,Li, Bin,Wang, Yong-Qiang
, p. 23727 - 23736 (2015/04/14)
A general and efficient method for the intermolecular direct C-7-selective C-H alkenylation of indolines using palladium(ii) as the catalyst and molecular oxygen as the sole oxidant has been developed. The reaction showed complete regio- and stereoselectivity. All products were E-isomers at the C-7 position, and no Z-isomers or other position substituted products could be detected. The approach also presented an efficient route for the synthesis of C-7 alkenylated indoles.
