- Stoichiometric and Catalytic Inter- and Intramolecular Hydroamination of Terminal Alkynes by Frustrated Lewis Pairs
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Frustrated Lewis pairs (FLPs) based on sterically encumbered anilines and the Lewis acid B(C6F5)3 were found to react with terminal alkynes effecting intermolecular hydroamination affording iminium alkynylborate species of the form [RPhN-C(R′)Me][R′CCB(C6F5)3]. In these cases, the reagent ratio of borane, aniline, and alkyne is 1:1:2. These reactions could also be performed in an intramolecular fashion by using anilines with alkynyl substituents effecting cyclization reactions. The use of 10mol % B(C6F5)3 under a H2 atmosphere provides a one-pot synthesis of the pyrrolidine 12, the piperidines 13-15, the azepane 16, the isoindoline 17, and the benzoxazine 18. Frustrated but satisfied: B(C6F5)3 was used to effect the stoichiometric and catalytic hydroamination of terminal alkynes by substituted anilines. Both inter- and intramolecular systems were explored in this reactivity. The mechanism adheres to previously observed frustrated Lewis pair reactivity.
- Mahdi, Tayseer,Stephan, Douglas W.
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- A Concise Route to Cyclic Amines from Nitroarenes and Ketoacids under Iron-Catalyzed Hydrosilylation Conditions
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Starting from nitroarenes, under hydrosilylation conditions, using a well-defined N-heterocyclic carbene iron(0) catalyst, (IMes)Fe(CO)4, the corresponding aniline derivatives were produced in 61–92% isolated yields. More impressively, a selective synthesis of cyclic amines such as pyrrolidines, piperidines and azepanes were conducted from levulinic acid, 1,5- and 1,6-keto acids, respectively. The sequential procedure proceeded under both visible light irradiation and thermal conditions with 20 examples in isolated yields up to 69%. (Figure presented.).
- Ammaiyappan, Yuvaraj,Darcel, Christophe,Tongdee, Satawat,Wu, Jiajun
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p. 3859 - 3865
(2021/07/12)
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- Catalyst-free photodecarbonylation ofortho-amino benzaldehyde
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It is almost a consensus that decarbonylation of the aldehyde group (-CHO) needs to not only be mediated by transition metal catalysts, but also requires severe reaction conditions (high temperature and long reaction time). In this work, inspired by the “conformational-selectivity-based” design strategy, we broke this consensus and discovered a catalyst-free photodecarbonylation of the aldehyde group. It revealed that decarbonylation can be easily achieved with visible light irradiation by introducing a tertiary amine into theortho-position of the aldehyde group. A diverse array of tertiary amines is tolerated by our photodecarbonylation under mild conditions. Furthermore, the (QM) computations of the mechanism and the experiments on well-designed special substrates revealed that our photodecarbonylation depends on the conformational specificity of the aldehyde group and tertiary amine, and occurs through an unusual [1,4]-H shift and a subsequent [1,3]-H shift.
- Li, Lamei,Wang, Songping,Wei, Wentao,Yan, Ming,Zhou, Jingwei
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supporting information
p. 3421 - 3426
(2020/06/25)
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- Investigation towards the reductive amination of levulinic acid by B(C6F5)3/hydrosilane system
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The selective transformation of the renewable biomass resources into the highly value-added platform chemicals is essentially important for sustainable chemistry. Here we report a simple and highly efficient strategy for the synthesis of N-heterocyclic co
- He, Jianghua,Wang, Tianlong,Xu, Hai,Zhang, Yuetao
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- Photo-induced dealdehyding method
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The invention provides a photo-induced dealdehyding method, and belongs to the technical field of organic synthesis. The photo-induced dealdehyding method comprises the following steps that a mixtureof a compound shown in the formula I and a solvent are reacted under an inert gas atmosphere and visible light irradiation, a dealdehyding product is obtained, and no photocatalyst is used in the whole process; wherein the structural formula of the formula I shown in the specification, R is a functional group and is selected from hydrogen, methyl, methoxyl, cyano, chlorine, bromine or fluorine. According to the photo-induced dealdehyding method, in the inert gas atmosphere, the compound shown in the formula (I) can be excited to generate carbon-oxygen bond homogeneous cracking through visiblelight irradiation, then free radical migration and double bond displacement are conducted, finally carbon monoxide is removed, aldehyde group removal is completed, no photocatalyst is needed in the whole process, operation is easy and convenient, and conditions are mild.
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Paragraph 0048-0053; 0144-0149
(2020/06/16)
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- Synthesis method for converting lignin 4-O-5 model compound diaryl ether into nitrogen-containing compound
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The invention discloses a synthesis method for converting lignin 4-O-5 model compound diaryl ether into a nitrogen-containing compound. According to the synthesis method, a diaryl ether compound andan amine compound are subjected to a heating reaction in a certain amount of a solvent (containing a certain amount of water) in an argon atmosphere (containing a certain amount of air) under the actions of a metal catalyst and sodium borohydride, such that the drug with the important physiological activity or the compound with the natural product skeleton containing nitrogen is formed by directlycoupling the C-O bond cut and the amine compound cross while the corresponding aromatic hydrocarbon is obtained. According to the present invention, the synthesis method has characteristics of simpleand easily-available raw materials, high conversion rate, important product and good yield, and has broad application prospects in the degradation and deep development and utilization of lignin.
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Paragraph 0027-0029
(2019/04/26)
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- Iron-Catalysed Switchable Synthesis of Pyrrolidines vs Pyrrolidinones by Reductive Amination of Levulinic Acid Derivatives via Hydrosilylation
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A selective production of pyrrolidines vs pyrrolidinones via hydrosilylation of levulinic acid and levulinates by switching of the iron complex catalyst is presented herein. The reactions proceeded efficiently with various anilines and alkylamines under both visible light irradiation and thermal conditions with 43 examples in isolated yields up to 93%. Noticeably, under similar conditions, cyclic amines such as piperidines and azepanes were efficiently synthesized with yields up to 92%, by reaction of anilines with 1,5- or 1,6-keto acids, respectively. Similarly, N-arylinsolidoline compounds can be prepared from 2-formylbenzoic acid in 57–93% yields. (Figure presented.).
- Wei, Duo,Netkaew, Chakkrit,Darcel, Christophe
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supporting information
p. 1781 - 1786
(2019/02/26)
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- Palladium-Catalyzed Formal Cross-Coupling of Diaryl Ethers with Amines: Slicing the 4-O-5 Linkage in Lignin Models
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Lignin is the second most abundant organic matter on Earth, and is an underutilized renewable source for valuable aromatic chemicals. For future sustainable production of aromatic compounds, it is highly desirable to convert lignin into value-added platform chemicals instead of using fossil-based resources. Lignins are aromatic polymers linked by three types of ether bonds (α-O-4, β-O-4, and 4-O-5 linkages) and other C?C bonds. Among the ether bonds, the bond dissociation energy of the 4-O-5 linkage is the highest and the most challenging to cleave. To date, 4-O-5 ether linkage model compounds have been cleaved to obtain phenol, cyclohexane, cyclohexanone, and cyclohexanol. The first example of direct formal cross-coupling of diaryl ether 4-O-5 linkage models with amines is reported, in which dual C(Ar)?O bond cleavages form valuable nitrogen-containing derivatives.
- Zeng, Huiying,Cao, Dawei,Qiu, Zihang,Li, Chao-Jun
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supporting information
p. 3752 - 3757
(2018/03/13)
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- n-Butyllithium-mediated synthesis of N-aryl tertiary amines by reactions of fluoroarenes with secondary amines at room temperature
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A simple and facile method for the synthesis of aromatic tertiary amines by amination of fluoroarenes with secondary amines in the presence of n-butyllithium at room temperature was reported.
- Lin, Yingyin,Li, Meng,Ji, Xinfei,Wu, Jingjing,Cao, Song
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p. 1466 - 1472
(2017/02/18)
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- Reductive amination/cyclization of levulinic acid to pyrrolidones: Versus pyrrolidines by switching the catalyst from AlCl3 to RuCl3 under mild conditions
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Herein the reductive amination/cyclization of levulinic acid using phenylsilane was presented to selectively produce pyrrolidones versus pyrrolidines under mild conditions by switching the catalyst from AlCl3 to RuCl3. Using AlCl3 as the catalyst, pyrrolidones were solely obtained at room temperature, while RuCl3 as the catalyst selectively afforded pyrrolidines in high yields at 45 °C.
- Liu, Zhimin,Wu, Cailing,Luo, Xiaoying,Zhang, Hongye,Liu, Xinwei,Ji, Guipeng,Liu, Zhenghui
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supporting information
p. 3525 - 3529
(2017/08/15)
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- Reductive Amination/Cyclization of Keto Acids Using a Hydrosilane for Selective Production of Lactams versus Cyclic Amines by Switching of the Indium Catalyst
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Described herein is that the catalytic construction of N-substituted five- and six-membered lactams from keto acids with primary amines by reductive amination, using an indium/silane combination. This relatively benign and safe catalyst/reductant system tolerates the use of a variety of functional groups, especially ones that are reduction-sensitive. A direct switch from synthesizing lactams to synthesizing cyclic amines is achieved by changing the catalyst from In(OAc)3 to InI3. This conversion occurs by further reduction of the lactam using the indium/silane pair.
- Ogiwara, Yohei,Uchiyama, Takuya,Sakai, Norio
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supporting information
p. 1864 - 1867
(2016/02/03)
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- Porous chitosan microspheres supported-palladium catalyst for the C-N cross-coupling of aryl halides with secondary amines
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Porous chitosan microspheres-supported palladium catalysed the amination of aryl halides with a wide variety of secondary amines to yield the corresponding cross-coupling products under aerobic conditions. Both aryl bromides and iodides gave good to excellent yields of N,N-disubstituted anilines. The procedure can tolerate common functional groups such as chloro, methoxyl and nitro. The heterogeneous catalysis is efficienct and the catalyst could be recycled seven times without obvious decreased conversion.
- Cheng, Kai,Zeng, Minfeng,Qi, Chenze
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- Umpolung amination: Nickel-catalyzed coupling reactions of N,N-dialkyl-N-chloroamines with diorganozinc reagents
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(Chemical Equation Presented) N,N-Dialkyl-N-chloroamines are an effective source of electrophilic nitrogen for nickel-catalyzed coupling with diarylzinc reagents. A variety of N-chloroamines as well as organozinc reagents react smoothly under the reaction conditions. A one-pot procedure that circumvents the need to isolate the N-chloroamines is described.
- Barker, Timothy J.,Jarvo, Elizabeth R.
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supporting information; experimental part
p. 15598 - 15599
(2010/01/29)
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- Diastereoselective preparation of 2,4,6-trisubstituted-2'-cyanopiperidines: application to the construction of the carbon framework of perhydrohistrionicotoxin.
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The anodic cyanation of methanolic solutions of the 2-alkyl-N-phenylpiperidines 6b-d was performed in a flow cell equipped with a graphite felt anode. The reaction led to the formation of the 2-cyano-6-alkyl-N-phenylpiperidines 2b-d and proceeded with a high degree of regioselectivity. The 1H NMR spectra of the aminonitriles 2b-d showed an epimeric mixture at C-6. The major isomer has a trans configuration in which the cyano group is axial and the alkyl substituent is equatorial. Conversely, electrochemical oxidation of the 4-methyl-6-pentyl-N-phenylpiperidine 6e afforded the trisubstituted aminonitrile 2e as a single diastereomer (> 98% de). The 4-cyanobutyl side chain was incorporated in a two-step procedure to yield dinitrile 4e. This latter compound was directly converted into spiropiperidine 5e by using the Thorpe-Ziegler annulation procedure. The overall sequence (4 steps, 43%) allows the construction of the basic carbon framework of perhydrohistrionicotoxin.
- Malassene, Richard,Vanquelef, Enguerran,Toupet, Loic,Hurvois, Jean-Pierre,Moinet, Claude
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p. 547 - 551
(2007/10/03)
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- N-phenyl-substituted pyrrolidines, piperidines and azabicyclics by a tandem reduction-double reductive amination reaction
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N-Phenyl-substituted pyrrolidines and piperidines have been synthesized by catalytic reduction of nitrobenzene in the presence of 4- and 5-oxoaldehydes, respectively. The process involves reduction of the aromatic nitro group to give the N-phenylhydroxylamine or aniline followed by reductive amination with the two carbonyl functional groups. Monocyclic systems are generally formed in high yield and are easily purified. The method has also been extended to the synthesis of fused N-phenylazabicyclics from 2-(3-oxopropyl)cycloalkanones. A high degree of diastereoselectivity for the trans-fused product is observed in substrates having an ester group α to the cycloalkanone carbonyl. Bicyclic precursors lacking this ester group give mixtures of cis and trans products. Finally, contrary to previous reports, we have demonstrated that aniline can be substituted for nitrobenzene in these reactions.
- Bunce, Richard A.,Herron, Derrick M.,Lewis, Jason R.,Kotturi, Sharadsrikar V.
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p. 113 - 120
(2007/10/03)
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- SYNTHESIS OF STERICALLY HINDERED 1-ARYLPYRROLIDINES AND 1-ARYLPIPERIDINES BY CONDENSATION OF PRIMARY AROMATIC AMINES WITH CYCLIC ETHERS OR DIOLS
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A variety of 1-(o-alkylphenyl)- and 1-(o-o'-dialkylphenyl)-pyrrolidines and -piperidines were prepared by the gas phase alumina mediated condensation of tetrahydrofuran (THF), tetrahydropyran (THP) or the corresponding diols with primary aromatic amines in fair to high yield.This methodology can also be used for the synthesis of 1-phenylhexahydroazepine from aniline.A mechanistic interpretation of the catalytic action of alumina is presented.
- Walkup, Robert E.,Searles, Scott
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p. 101 - 106
(2007/10/02)
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- Novel Synthesis of the Pyrrolizidine Skeleton by Sulfenocycloamination. Total Synthesis of (+/-)-Retronecine and (+/-)-Turneforcidine
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The ω-unsaturated amines 1, 6, and 7 were converted into pyrrolidines 4 and 8 and piperidine 9, respectively, by treatment of their hydrochlorides with benzenesulfenyl chloride followed by base-induced ring closure.This novel sulfenocycloamination ring closure was applied to the synthesis of the pyrrolizidine ring (e.g., 20) and to the total synthesis of (+/-)-retronecine (32) and (+/-)-turneforcidine (34).
- Ohsawa, Tatsushi,Ihara, Masataka,Fukumoto, Keiichiro,Kametani, Tetsuji
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p. 3644 - 3648
(2007/10/02)
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