- Diastereoselective Desymmetrization of p-Quinamines through Regioselective Ring Opening of Epoxides and Aziridines
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A highly diastereoselective desymmetrization of p-quinamines via regioselective ring opening of epoxides and aziridines under mild conditions has been developed. A chairlike six-membered transition state with minimized 1,3-diaxial interactions explains the relative stereoselectivity of the cyclization reaction. This transition-metal free [3 + 3] annulation reaction provides rapid access to fused bicyclic morpholines and piperazines with a tetrasubstituted carbon center in high yields. In addition, it also allows the synthesis of enantioenriched products by using easily accessible chiral nonracemic epoxides and aziridines.
- Jadhav, Sandip B.,Chegondi, Rambabu
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- Exploration of flow reaction conditions using machine-learning for enantioselective organocatalyzed Rauhut-Currier and [3+2] annulation sequence
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A highly atom-economical enantioselective organocatalyzed Rauhut-Currier and [3+2] annulation sequence has been established by using a flow system. Suitable flow conditions were explored through reaction screening of multiple parameters using machine learning. Eventually, functionalized chiral spirooxindole analogues were obtained in high yield with good ee as a single diastereomer within one minute.
- Kondo, Masaru,Wathsala,Sako, Makoto,Hanatani, Yutaro,Ishikawa, Kazunori,Hara, Satoshi,Takaai, Takayuki,Washio, Takashi,Takizawa, Shinobu,Sasai, Hiroaki
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- (3 + 2)-Annulation of p-Quinamine and Aryne: A Strategy to Construct the Multisubstituted Hydrocarbazoles
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A strategy for the synthesis of multisubstituted hydrocarbazoles has been developed through (3 + 2)-annulation of p-quinamines and arynes. In this way, new analogs of hydrocarbazoles with quaternary carbon center can be synthesized in satisfactory yield under mild conditions. Furthermore, this (3 + 2)-annulation can be easily scaled-up, and the products can be modified through simple transformation.
- Xu, Dengyu,Zhao, Yulong,Song, Dengpeng,Zhong, Zhuliang,Feng, Shangbiao,Xie, Xingang,Wang, Xiaolei,She, Xuegong
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- Lewis Base Promoted, Direct 1,4-Conjugate Addition to Quinone Imine Ketals: Efficient Access to Unsymmetrical Diaryl Sulfones
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An alternative approach with eco-friendliness and high efficiency for the preparation of unsymmetrical diaryl sulfones has been developed. The strategy takes advantage of the reaction of sulfonyl hydrazides with quinone imine ketals catalyzed by DABCO (triethylenediamine) in ethanol. This transformation proceeds via a Lewis base promoted, direct 1,4-conjugate addition/sulfonylation/alcohol elimination reaction sequence. The protocol provides an efficient approach to access an array of diverse unsymmetrical diaryl and heterodiaryl sulfones, aryl alkyl sulfones and aryl vinyl sulfones in good to excellent yields.
- Liu, Teng,Liu, Jianjun,Shen, Xianfu,Xu, Jianbin,Nian, Beifang,He, Ni,Zeng, Shunqun,Cheng, Feixiang
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- Oxidative Radical-Mediated Addition of Ethers to Quinone Imine Ketals: An Access to Hemiaminals
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The highly regioselective synthesis of substituted hemiaminal via addition of ethers to quinone imine ketals (QIKs) has been developed under metal-free conditions. In the presence of tetrabutylammonium chloride and potassium persulfate (K2S2O8), QIKs coup
- More, Satish G.,Kamble, Rohit B.,Suryavanshi, Gurunath
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- Accessing bridged bicyclic compounds or meta carbon-functionalized anilines from the dearomatization of anilines
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The oxidative dearomatization of anilines was combined with a domino Michael addition, providing a series of nitrogen-containing bridged bicyclic compounds in moderate to excellent yields. The bridged bicyclic compound could be converted into the correspo
- Wang, Linfei,Wang, Shuo-En,Wang, Weibin,Fan, Renhua
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- Lewis Acid Regulated Divergent Catalytic Reaction between Quinone Imine Ketals (QIKs) and 1,3-Dicarbonyl Compounds: Switchable Access to Multiple Products Including 2-Aryl-1,3-Dicarbonyl Compounds, Indoles, and Benzofurans
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A catalytic Lewis acid regulated reaction between quinone imine ketals (QIKs) and 1,3-dicarbonyl compounds provides a divergent and tunable approach to a variety of skeletons, including a series of 2-aryl-1,3-dicarbonyl compounds, indoles, and benzofurans. The use of lithium chloride and ferrous bromide gives C3- or C2-alkylation products of the QIKs. The combination of ferrous bromide and trifluoromethanesulfonic acid delivers indole derivatives. Sequential hydrolysis and C3-alkylation occur in the presence of ytterbium (III) trifluoromethanesulfonate and stoichiometric amounts of water. When the reaction is performed with trifluoromethanesulfonic acid and stoichiometric amounts of water, benzofuran is obtained. This protocol utilizes mild conditions, exhibits regio- and chemoselectivity, and has broad functional group tolerance. (Figure presented.).
- Chen, Xingyu,Lu, Sixian,Deng, Ping,Chang, Xiaoqiang,Zhao, Yifan,Ma, Yue,Zhang, Dong,Xia, Fei,Yang, Lan,Wang, Jigang,Sun, Peng
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- Enantioselective dearomative [3+2] annulation of 5-amino-isoxazoles with quinone monoimines
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The first enantioselective dearomative [3+2] annulation of 5-amino-isoxazoles with quinone monoimines was realized using a chiral phosphoric acid as catalyst. Various novel (bridged) isoxazoline fused dihydrobenzofurans bearing two continuous quaternary stereocenters were achieved in moderate to good yields (up to 94%) with moderate to good enantioselectivities (up to 98% ee). The absolute configurations of two products were assigned by X-ray crystal structural analyses and a plausible reaction mechanism was proposed. This journal is
- Liu, Hui,Yan, Yingkun,Zhang, Jiayan,Liu, Min,Cheng, Shaobing,Wang, Zhouyu,Zhang, Xiaomei
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p. 13591 - 13594
(2020/11/17)
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- Highly chemo- and regioselective C-P cross-coupling reaction of quinone imine ketals with Ar2P(O)H to construct: Ortho -amino triarylphosphine derivatives
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A highly chemo- and regioselective approach for the construction of ortho-amino triarylphosphine oxides has been achieved through a C-P cross-coupling reaction involving quinone imine ketals (QIKs) with Ar2P(O)H and catalyzed via a Lewis base. This alternative protocol provided a wide substrate scope with excellent yields (82-95%), and a variety of ortho-amino triarylphosphines were obtained with high yields (87-95%) via further reductive reaction. Furthermore, this reaction could be scaled-up and several synthetic transformations were accomplished for the construction of functionalized organophosphorus.
- Liu, Teng,Li, Yongqin,Cheng, Feixiang,Shen, Xianfu,Liu, Jianjun,Lin, Jun
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p. 3536 - 3541
(2019/07/10)
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- Transition-Metal-Free Regioselective One-Pot Synthesis of Aryl Sulfones from Sodium Sulfinates via Quinone Imine Ketal
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A novel, efficient, and regioselective transition-metal-free one-pot synthesis of aryl sulfones via the reactive quinone imine ketal intermediate is demonstrated using easily accessible bench-stable sulfinate salts. A broad range of functionality on p-ani
- Halder, Priyanka,Humne, Vivek T.,Mhaske, Santosh B.
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p. 1372 - 1378
(2019/01/30)
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- Mitsunobu-initiated cascade cyclization of p-quinamines and 2-furanylmethanols: highly regio- and diastereoselective synthesis of functionalized hydrobenzo[c,d]indoles
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A cascade cyclization of para-quinamines and 2-furanylmethanol has been achieved, affording a series of functionalized hydrobenzo[c,d]indoles in moderate to good yields and excellent diastereoselectivities under mild conditions. This reaction was first initiated by the Mitsunobu reaction and then followed by the [4 + 2] Diels-Alder reaction to furnish the important indole-fused heterocyclic derivatives.
- Cao, Bo,Wei, Yin,Shi, Min
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supporting information
p. 3737 - 3740
(2019/04/17)
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- A chemical synthesis asymmetric structure dihalodiarylsulfone method (by machine translation)
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A chemical synthesis asymmetric structure dihalodiarylsulfone method, to substituted aniline compound 1 as a starting raw material, first on the aniline Ts (toluene sulfonyl) protection or Boc (tert-butoxy carbonyl) protection of the compound 2 or 4. Under the room temperature condition, compound 2 or 4 is dissolved in methanol or ethanol or isopropanol, then under the protection of nitrogen [...] diacetic acid [PhI (OAc)2 ] Oxidation to obtain compound 3 or 5. In the three ethylene diamine (DABCO) as catalyst and polyethylene glycol (PEG - 400) as reaction solvent 40 o C conditions, compound 5 with compound 6 in 1, 4 - conjugate addition reaction/sulfonylimines acylation reaction asymmetric structure dihalodiarylsulfone 7. The raw material is cheap and easy to obtain, reaction selectivity, and reaction solvent polyethylene glycol (PEG - 400) can be recycled 4 - 5 times less environmental pollution, high yield and easy application and the like. (by machine translation)
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- Phosphine-catalyzed intramolecular Rauhut-Currier reaction: Enantioselective synthesis of hydro-2: H -indole derivatives
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A highly enantioselective intramolecular Rauhut-Currier reaction catalyzed by a multifunctional chiral aminophosphine catalyst was reported. A series of hydro-2H-indole derivatives that bear an all-carbon quaternary center were obtained in high yields (up to 94%), and excellent diastereo- and enantioselectivities (up to >20:1 dr and >99% ee). And this reaction could be performed on a gram scale using 2 mol% catalyst loading.
- Jin, Hongxing,Zhang, Qinglong,Li, Erqing,Jia, Penghao,Li, Ning,Huang, You
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p. 7097 - 7101
(2017/09/07)
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- Naturally active drug intermediate with high biological activity and preparation method thereof
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The present invention the invention relates to a preparation method for a naturally active drug intermediate with high biological activity. The preparation method comprises the following steps: synthesizing a reaction substrate from raw materials under th
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Paragraph 0024; 0025
(2017/08/19)
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- Destruction and Construction: Application of Dearomatization Strategy in Aromatic Carbon-Nitrogen Bond Functionalization
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The formation of carbon-carbon bonds through the functionalization of aromatic carbon-nitrogen bonds is a highly attractive synthetic strategy in the synthesis of aromatic molecules. In this paper, we report a novel aromatic carbon-nitrogen bond functionalization reaction by using a simple dearomatization strategy. Through this process para-substituted anilines serve as a potential aryl source in the construction of a range of functionalized aromatic molecules, such as quaternary carbon centers, α-keto esters, and aldehydes.
- Wang, Shuo-En,Wang, Linfei,He, Qiuqin,Fan, Renhua
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supporting information
p. 13655 - 13658
(2015/11/11)
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- Br?nsted acid-controlled [3 + 2] coupling reaction of quinone monoacetals with alkene nucleophiles: A catalytic system of perfluorinated acids and hydrogen bond donor for the construction of benzofurans
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We have developed an efficient Br?nsted acid-controlled strategy for the [3 + 2] coupling reaction of quinone monoacetals (QMAs) with nucleophilic alkenes, which is triggered by the particular use of a specific acid promoter, perfluorinated acid, and a solvent, fluoroalcohol. This new coupling reaction smoothly proceeded with high regiospecificity in regard with QMAs for introducing π-nucleophiles to only the carbon α to the carbonyl group, thereby providing diverse dihydrobenzofurans and derivatives with high yields, up to quantitative, under mild conditions in short reaction times. The choice of Br?nsted acid enabled us to avoid hydrolysis of the QMAs, which gives quinones, and the formation of discrete cationic species from the QMAs. Notably, further investigations in this study with regard to the acid have led to the findings that the originally stoichiometrically used acid could be reduced to a catalytic amount of 5 mol % loading or less and that the stoichiometry of the alkenes could be significantly improved down to only 1.2 equiv. The facts that only a minimal loading (5 mol %) of perfluoroterephthalic acid is required, readily available substrates can be used, and the regioselectivity can be controlled by the acid used make this coupling reaction very fascinating from a practical viewpoint.
- Hu, Yinjun,Kamitanaka, Tohru,Mishima, Yusuke,Dohi, Toshifumi,Kita, Yasuyuki
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p. 5530 - 5543
(2013/07/26)
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- One-pot synthesis of diarylamines from two aromatic amines via oxidative dearomatization-imino exchange-reductive aromatization
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A one-pot synthetic strategy for diarylamines using only aromatic amines as starting materials has been developed. This method involved a PhI(OAc) 2-induced oxidative dearomatization of N-sulfonyl protected para-substituted anilines, a Bi(OTf)3-catalyzed imino exchange reaction between N-sulfonyl cyclohexadienimines and aromatic amines, and a CF3COOH/Zn mediated reductive aromatization of the resulting N-aryl cyclohexadienimines.
- Zhang, Li,Wang, Weibin,Fan, Renhua
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supporting information
p. 2018 - 2021
(2013/05/23)
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- The Diels-Alder reactions of quinone imine ketals
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N-Benzoyl- and N-arylsulfonyl-p-benzoquinone-mono-imine ketals (QIKs) undergo smooth Diels-Alder cycloadditions with typical 1,3-butadienes to yield the expected endo adducts. Treatment with catalytic acid rapidly converts the adducts to dihydronaphthalen
- Banfield, Scott C.,Kerr, Michael A.
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p. 131 - 138
(2007/10/03)
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- Spirodienones. Part 5. The Synthesis and Reactions of N-Sulphonylcyclohexadienimines
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The anodic or chemical oxidation of para-substituted sulphonanilides gives 4,4-disubstituted N-sulphonylcyclohexadienimines, which, from appropriately substituted anilines, may be spirocyclic.The scope and limitations of the synthesis are described, and mechanism proposed.The selective hydrolysis of the dienimines to the corresponding dienones provides a convenient route to the latter compounds.The reaction of some of the dienimines with dienes is discussed.
- Coutts, Ian G. C.,Culbert, Nicholas J.,Edwards, Mark,Hadfield, John A.,Musto, Donald R.,et al.
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p. 1829 - 1836
(2007/10/02)
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