- Dibrominative Spirocyclization of 2-Butynolyl Anilides: Synthesis of gem-Dibromospirocyclic Benzo[ d][1,3]oxazines and Their Application in the Synthesis of 4 H-Furo[3,2- b]indoles
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The combination of catalytic aqueous hydrochloric acid (HCl) and N-bromosuccinimide (NBS) generated electrophilic bromine monochloride (BrCl), which readily induced spiroannulation of 2-alkynolyl anilides (n = 1-3) to form gem-dibromospirocyclic benzo[d][
- Chaisan, Nattawadee,Ruengsangtongkul, Sureeporn,Tummatorn, Jumreang,Ruchirawat, Somsak,Chainok, Kittipong,Thongsornkleeb, Charnsak
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p. 4671 - 4698
(2021/04/06)
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- Iodine-Catalyzed Synthesis of Substituted Furans and Pyrans: Reaction Scope and Mechanistic Insights
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Substituted pyrans and furans are core structures found in a wide variety of natural products and biologically active compounds. Herein, we report a practical and mild catalytic method for the synthesis of substituted pyrans and furans using molecular iodine, a simple and inexpensive catalyst. The method described is performed under solvent-free conditions at an ambient temperature and atmosphere, thus offering a facile and practical alternative to currently available reaction protocols. A combination of experimental studies and density functional theory calculations revealed interesting mechanistic insights into this seemingly simple reaction.
- Pace, Domenic P.,Robidas, Rapha?l,Tran, Uyen P. N.,Legault, Claude Y.,Nguyen, Thanh Vinh
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p. 8154 - 8171
(2021/06/28)
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- Silver-Catalyzed Oxyphosphorylation of Unactivated Alkynes
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Here, we describe an application of hydroazidation in the instant activation of alkynes for achieving the oxyphosphorylation of unactivated alkynes with diarylphosphinoyl radicals under mild reaction conditions. This reaction provides a method for accessing β-ketophosphine oxides and phosphorus-containing pyrroles. (Figure presented.).
- Liu, Binbin,Song, Qingmin,Liu, Zhaohong,Wang, Zikun
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supporting information
p. 3214 - 3219
(2021/05/27)
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- Regioselective Crossed Aldol Reactions under Mild Conditions via Synergistic Gold-Iron Catalysis
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A synergistic gold-iron (Au-Fe) catalytic system was developed for sequential alkyne hydration and vinyl Au addition to aldehydes or ketones. Fe(acac)3 was identified as an essential co-catalyst in preventing vinyl Au protodeauration and facilitating nucleophilic additions. Effective C–C bond formation was achieved under mild conditions (room temperature) with excellent regioselectivity and high efficiency (1% [Au], up to 95% yields). The intramolecular reaction was also achieved, giving successful macrocyclization (16–31 ring sizes) with excellent yields (up to 90%, gram scale) without extended dilution (0.2 M), which highlights the great potential of this new crossed aldol strategy in challenging target molecule synthesis. Effective construction of the C–C bond is one of the most important tasks in organic synthesis. Whereas aldol condensation is a classic C–C bond-forming transformation, it requires other chemical promoters, such as strong base and reactive acidic catalysts. As a result, the overall transformation is limited in terms of ideal atom economy and environmentally friendly operation. With the discovery of a gold-iron (Au-Fe) synergistic catalysis system, here we describe a new approach to facilitating alkyne hydration and sequential vinyl Au addition to carbonyls. This approach gives the C–C bond-forming products in excellent yields, wide substrate scope, and great functional-group compatibility under mild conditions. This protocol can also be applied to macrocyclization without extended dilution. This C–C bond-forming strategy could facilitate challenging molecule synthesis in chemical, biological, and medicinal research. We report a synergistic gold-iron (Au-Fe) catalytic system to access vinyl Au reactivity by avoiding frequently occurring protodeauration. Fe(acac)3 was identified as an essential co-catalyst, facilitating vinyl Au addition to aldehydes. A broad substrate scope was obtained under mild conditions (room temperature) with excellent regioselectivity and high efficiency (1% [Au], up to 95% yields). This protocol offers a practical solution for achieving macrocyclization (16–31 ring sizes, up to 90%, gram scale) without extended dilution, highlighting the synthetic utility in complex molecular synthesis.
- Chen, Hao,Jean, Jonathan,Shan, Chuan,Shi, Xiaodong,Teng, Shun,Wang, Jin,Wojtas, Lukasz,Ye, Xiaohan,Yi, Yaping,Yuan, Teng,Zhao, Pengyi
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supporting information
p. 1420 - 1431
(2020/06/19)
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- Synthesis of 2,2,2-Trifluoroethyl Oxazoles, Oxazolines and Furans via Alkyne Oxytrifluoromethylation
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This study reports an oxytrifluoromethylation method for construction of oxazoles and furans motif and the concurrent incorporation of a 2,2,2-trifluoroethyl group at the aromatic C5-position. High-valent copper(III) trifluoromethyl compounds are crucial
- Dong, Jia-Jia,Zhang, Song-Lin
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supporting information
p. 795 - 800
(2020/01/24)
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- Rate Enhancement in CAN-Promoted Pd(PPh3)2Cl2-Catalyzed Oxidative Cyclization: Synthesis of 2-Ketofuran-4-carboxylate Esters
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Stoichiometric ceric ammonium nitrate (CAN) and a catalytic amount of Pd(PPh3)2Cl2 (5 mol %) can rapidly produce multisubstituted 2-ketofuran-4-carboxylate esters from 2-propargylic 1,3-ketoesters via oxidative O-cyclization reaction. Pd(PPh3)2Cl2 was found to be the crucial catalyst as its inclusion greatly enhanced the rate of the reaction and cleanly afforded the products within minutes. Over 30 substrates were successfully converted to the desired compounds in mostly moderate to good yields.
- Ruengsangtongkul, Sureeporn,Chaisan, Nattawadee,Thongsornkleeb, Charnsak,Tummatorn, Jumreang,Ruchirawat, Somsak
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supporting information
p. 2514 - 2517
(2019/04/30)
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- Fe(II)/Au(I) Relay Catalyzed Propargylisoxazole to Pyridine Isomerization: Access to 6-Halonicotinates
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An efficient synthesis of methyl nicotinates/6-halonicotinates by the domino isomerization of 4-propargyl/(3-halopropargyl)-5-methoxyisoxazoles under Fe(II)/Au(I) relay catalysis was developed. It was found that FeNTf2 is an effective catalyst
- Galenko, Alexey V.,Shakirova, Firuza M.,Galenko, Ekaterina E.,Novikov, Mikhail S.,Khlebnikov, Alexander F.
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p. 5367 - 5379
(2017/05/24)
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- Bi(OTf)3-mediated cycloisomerization of γ-alkynyl arylketones: Application to the synthesis of substituted furans
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A novel Bi(OTf)3-mediated cycloisomerization of γ-alkynyl arylketones 4, 7, or 10 with molecular sieve (MS) in MeNO2 affords 3-substituted furans 3, 8, or 11 at rt for 3 h in moderate to good yields. The method provides mild, less-to
- Chang, Meng-Yang,Cheng, Yu-Chieh,Lu, Yi-Ju
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p. 1264 - 1267
(2015/03/14)
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- Indium-catalyzed synthesis of furans and pyrroles via cyclization of α-propargyl-β-keto esters
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In(OTf)3 or In(NTf2)3 effectively catalyze the cyclo-isomerization reaction of -propargyl - keto esters and their imine analogues to afford trisubstituted furans and pyrroles, respectively. Both terminal and internal alkyn
- Tsuji, Hayato,Yamagata, Ken-Ichi,Ueda, Yasuyuki,Nakamura, Eiichi
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supporting information; experimental part
p. 1015 - 1017
(2011/06/17)
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- Furan synthesis through AuCl3-catalysed cycloisomerisation of β-alkynyl β-ketoesters
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AuCl3 efficiently catalyses the cycloisomerisation of readily available β-alkynyl β-ketoesters to generate trisubstituted furans. The substrate scope is wide and the reaction is high yielding and operationally simple.
- Rodríguez, Arantxa,Moran, Wesley J.
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supporting information; experimental part
p. 2605 - 2607
(2011/06/21)
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- New anionic cyclization of 4- and 5-alkynylamines: Synthesis of 2-Benzylidene pyrrolidines and piperidines
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Treatment of 4- and 5-alkynylamines with 0.5-1.2 equiv. of butyllithium brought about a facile anionic cyclization, giving the corresponding enamine pyrrolidines and piperidines having an exo double bond in high yields. Treatment of 4-alkynamides with lit
- Tokuda, Masao,Fujita, Hirotake,Nitta, Makoto,Suginome, Hiroshi
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p. 385 - 395
(2007/10/02)
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- HIGH YIELD SYNTHESIS OF α PROPARGYLIC ACRYLIC ESTER : A GENERAL ACCESS TO α SUBSTITUTED ACRYLIC ESTERS
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A heterogeneous mediated, high yield, monopropargylation of ethyl benzoylacetate followed by a methylenation reaction using a formaldehyde addition-benzoyl elimination mechanism is described.This useful method is extended to the synthesis of α substituted acrylic esters.
- Queignec, Rene,Kirschleger, Bernard,Lambert, Francois,Aboutaj, Mohammed
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p. 1213 - 1224
(2007/10/02)
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