- Palladium-catalyzed difunctionalization of internal alkynes via highly regioselective 6- endo cyclization and alkenylation of enynoates: Synthesis of multisubstituted pyrones
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An efficient Pd(II)-catalyzed difunctionalization reaction of internal alkynes is reported. In this reaction, various enynoates and electron-deficient alkenes were used for the syntheses of useful highly substituted pyrone derivatives via a 6-endo cycliza
- Tian, Pan-Pan,Cai, Sai-Hu,Liang, Qiu-Ju,Zhou, Xing-Yi,Xu, Yun-He,Loh, Teck-Peng
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- Essential structural features of (2Z,4E)-5-phenylpenta-2,4-dienoic acid for inhibition of root gravitropism
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Previously, we found (2Z,4E)-5-phenylpenta-2,4-dienoic acid (ku-76) to be a selective inhibitor of root gravitropic bending of lettuce radicles at 5 μM, with no concomitant growth inhibition. Here, we describe a structure-activity relationship study of ku
- Shindo, Mitsuru,Makigawa, Saki,Matsumoto, Kenji,Iwata, Takayuki,Wasano, Naoya,Kano, Arihiro,Morita, Miyo Terao,Fujii, Yoshiharu
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- Fe(III)-Catalyzed, Cyclizative Coupling between 2-Alkynylbenzoates and Carbinols: Rapid Generation of Polycyclic Isocoumarins and Phthalides and Mechanistic Study
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FeCl3 catalyzed, highly regioselective cyclizative coupling of internal alkynes with alcohols has been reported for the rapid synthesis of structurally divergent, complex isocoumarins and phthalides respectively in intermolecular and intramolecular fashion. This strategy exhibited very high substrate scope and efficiency and proceeds through the simultaneous formation of C?O and C?C bonds. Observations from a series of control experiments supported a) the mechanism as Lewis acid catalyzed dual activation of ester and alcohol, b) the role of carbocation for the enhanced rates of cyclization, i. e., activation of alkyne by carbocation, and c) no role of HCl in the reported cascade process. (Figure presented.).
- Gandhi, Soniya,Baire, Beeraiah
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supporting information
p. 2651 - 2657
(2020/05/25)
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- In Situ Generation of Alkynylzinc and Its Subsequent Negishi Reaction in a Flow Reactor
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A highly efficient and convenient Negishi cross-coupling reaction has been developed for the synthesis of unsymmetrical alkynes and enynes in a continuous-flow process. The reaction proceeds through an in situ generated alkynylzinc reagent by the reaction of lithium acetylide with zinc halide at room temperature followed by a cross-coupling reaction with aryl or vinyl iodides. The notable features of this work compared to the conventional benchtop method are mild reaction conditions, good to excellent yields, broad functional-group compatibility, short residence time (73 sec) and especially desilylation of TMS group with the residence time of only 10.5 sec.
- Kandasamy, Mohanraj,Huang, Yu- Hsuan,Ganesan, Balaji,Senadi, Gopal Chandru,Lin, Wei-Yu
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p. 4349 - 4356
(2019/07/03)
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- Palladium-Catalyzed One-Pot Highly Regioselective 6- Endo Cyclization and Alkylation of Enynoates: Synthesis of 2-Alkanone Pyrones
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The Pd(II)-catalyzed one-pot tandem cyclization/alkylation reactions of enynoates with allylic alcohols have been demonstrated. In this reaction, an innovative protocol proceeded well through Pd-catalyzed intramolecular selective 6-endo cyclization, inser
- Ahmad, Tanveer,Qiu, Sheng-Qi,Xu, Yun-He,Loh, Teck-Peng
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p. 13414 - 13426
(2018/11/02)
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- Facile synthesis of α, β-unsaturated esters through a one-pot copper-catalyzed aerobic oxidation-Wittig reaction
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An efficient one-pot synthesis of α, β-unsaturated esters through the aerobic oxidation – Wittig tandem reaction of alcohols and phosphorous ylide is developed. This new method operates under mild reaction conditions, and uses CuI/TEMPO (TEMPO = 2,2,6,6-tetramethylpiperidine-N-oxyl) as co-catalyst and air (O2) as the oxidant. It tolerates a wide range of functionalized benzylic alcohol and aliphatic alcohols.
- Ren, Cheng,Shi, Zhenyu,Ding, Weijie,Liu, Zhiqing,Jin, Huile,Yu, Xiaochun,Wang, Shun
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supporting information
p. 14 - 17
(2017/12/06)
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- Palladium-catalyzed convenient one-pot synthesis of multi-substituted 2-pyrones via transesterification and alkenylation of enynoates
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An efficient one-pot protocol for the synthesis of multi-substituted 2-pyrone derivatives from internal alkynes and unactivated alkenes is reported. The methodology involves difunctionalization of internal alkynes by using Pd(II) as a catalyst alongwith X-Phos as ligand via 6-endo transesterification and subsequent alkenylation pathway. Notable features include simple and easily available starting materials, including a range of unactivated alkenes, reduced synthetic steps and mild reaction conditions with high efficiency.
- Pathare, Ramdas S.,Sharma, Shivani,Gopal, Kandasamy,Sawant, Devesh M.,Pardasani, Ram T.
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supporting information
p. 1387 - 1389
(2017/03/17)
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- Catalyst-Free Synthesis of Borylated Lactones from Esters via Electrophilic Oxyboration
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A catalyst-free oxyboration reaction of alkynes is developed. The resulting borylated isocoumarins and 2-pyrones are isolated as boronic acids, pinacolboronate esters, or potassium organotrifluoroborate salts, providing a variety of bench-stable organobor
- Faizi, Darius J.,Issaian, Adena,Davis, Ashlee J.,Blum, Suzanne A.
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supporting information
p. 2126 - 2129
(2016/03/05)
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- Synthesis of Highly Substituted Racemic and Enantioenriched Allenylsilanes via Copper-Catalyzed Hydrosilylation of (Z)-2-Alken-4-ynoates with Silylboronate
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Copper-catalyzed highly efficient hydrosilylation reaction of enynoates was developed. Under simple reaction conditions, various di-, tri-, and tetrasubstituted racemic allene products could be obtained in high yields. The asymmetric 1,6-addition of silyl group to the (Z)-2-alken-4-ynoates could be achieved under mild reaction conditions to afford the silyl-substituted enantioenriched chiral allene products in good yields and with high enantioselectivities.
- Wang, Min,Liu, Zheng-Li,Zhang, Xiang,Tian, Pan-Pan,Xu, Yun-He,Loh, Teck-Peng
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supporting information
p. 14830 - 14833
(2015/12/08)
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- OMS-2 for aerobic, catalytic, one-pot alcohol oxidation-wittig reactions: Efficient access to α,β-unsaturated esters
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Manganese oxide octahedral molecular sieve (OMS) materials with well-defined pores have been extensively studied over two decades due to their intriguing chemical and physical properties. OMS-2, the synthetic cryptomelane form of manganese oxide, was synthesized by a modified reflux method and was found to be highly active for obtaining α,β-unsaturated esters (up to 95 % yield and with high diastereoselectivities) from a variety of benzyl, heteroaryl, allyl and alkyl alcohols via one-pot alcohol oxidation-Wittig reaction. The transformation utilizes air as the stoichiometric oxidant, and the inexpensive catalyst can be recovered and reused. Filter and use again! Porous manganese oxide molecular sieve based catalysts were found to efficiently promote the oxidation of a variety of alcohols to the aldehydes, which reacted insitu with stabilized Wittig reagent, providing almost exclusively E-α,β-unsaturated esters in good to excellent yields. The heterogeneous catalyst used was made from inexpensive starting materials, and the recovered catalyst was found to be reusable with a modest loss in activity.
- Kona, Jagadeswara R.,King'Ondu, Cecil K.,Howell, Amy R.,Suib, Steven L.
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p. 749 - 752
(2014/03/21)
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- Chemo-, regio- and stereoselective tricyclohexylphosphine-catalyzed [3+2] cycloaddition of enynes with [60]fullerene initiated by 1,4-michael addition: Synthesis of cyclopenteno[60]fullerenes and their electrochemical properties
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Herein we demonstrate a tricyclohexylphosphine-catalyzed cycloaddition of (E)- or (Z)-alkyl 5-substituted phenylpent-2-en-4-ynoates with [60]fullerene to give cyclopentenofullerenes in good to excellent yields, through initial chemo- and regioselective 1,4-addition of phosphines at the b-carbon of the enyne substrates. The nucleophilic addition pattern of P (cHx)3 is found to be different from that of Gilman or Grignard reagents toward the studied enynes. The resulting cyclopentenofullerenes, characterized with spectrometric methods and single crystal X-ray diffraction analysis, exhibit comparable or higher LUMO energy levels than a typical n-type material, [6,6]-phenyl-C61-butyric acid methyl ester (PCBM).
- Tseng, Po-Yen,Chuang, Shih-Ching
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supporting information
p. 2165 - 2171
(2013/10/01)
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- Gold-catalyzed cyclization of alkynylaziridines as an efficient approach toward functionalized N-phth pyrroles
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(Chemical Equation Presented) An efficient access to N-phth pyrrroles via gold-catalyzed cycloisomerization of N-phth alkynylaziridines has been described. Functionalized pyrroles including pyrrole-2-carboxylates or 2-pyrrolyl ketone are easily constructe
- Du, Xiangwei,Xie, Xin,Liu, Yuanhong
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supporting information; experimental part
p. 510 - 513
(2010/03/30)
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- Methods of 1,3-enyne preparation using copper (I) catalysts
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A copper(I) bi-dentate ligand complex-catalyzed procedure for synthesis of 1,3-enynes. The methods and/or systems of this invention afford a variety of enynes, tolerate a variety of sensitive functional groups, and can be employed without resort to expensive palladium reagents.
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Page/Page column 6; 18-19
(2009/01/24)
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- Ruthenium-catalyzed, one-pot alcohol oxidation-wittig reaction producing αβ unsaturated esters
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By a one-pot process, αβ-unsaturated esters were synthesized in high yield through the Ru-catalyzed oxidation of primary alcohols and the coupling of the resulting aldehydes and stabilized Wittig reagents. The ruthenium catalyst is composed of ruthenium nanoparticles embedded in aluminum oxyhydroxide and can be recovered simply by filtration or decantation. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009.
- Lee, Eun Young,Kim, Youngkwon,Lee, Jae Sung,Park, Jaiwook
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experimental part
p. 2943 - 2946
(2009/10/11)
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- Assembly of conjugated enynes and substituted indoles via CuI/amino acid-catalyzed coupling of 1-alkynes with vinyl iodides and 2- bromotrifluoroacetanilides
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(Chemical Equation Presented) Cross-coupling of 1-alkynes with vinyl iodides occurs at 80°C in dioxane catalyzed by CuI/N,N-dimethylglycine to afford conjugated enynes in good to excellent yields. Heating a mixture of 2-bromotrifluoroacetanilide, 1-alkyne, 2 mol % of CuI, 6 mol % of L-proline, and K2CO3 in DMF at 80 °C leads to the formation of the corresponding indole. This conversion involves a CuI/L-proline-catalyzed coupling between aryl bromide and the 1-alkyne followed by a CuI-mediated cyclization process. An ortho-substituent effect directed by NHCOCF3 enables me reaction to proceed under these mild conditions. Both aryl acetylenes and O-protected propargyl alcohol can be applied, leading to 5-, 6-, or 7-substituted 2-aryl and protected 2-hydroxymethyl indoles in good yields. With simple aliphatic alkynes, however, lower yields were observed.
- Liu, Feng,Ma, Dawei
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p. 4844 - 4850
(2008/02/05)
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- Copper(I)-catalyzed coupling of terminal acetylenes with aryl or vinyl halides
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Synthetic protocols using copper(I) catalysts for the formation of diaryl acetylenes, 1,3-enynes, benzofurans and indoles are described. Georg Thieme Verlag Stuttgart.
- Saejueng, Pranorm,Bates, Craig G.,Venkataraman
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p. 1706 - 1712
(2007/10/03)
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- Halogenated-2-pyrones in Sonogashira cross-coupling: limitations, optimisation and consequences for GC analysis of Pd-mediated reactions
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The Sonogashira couplings of 4-bromo-6-methyl-2-pyrone (5) with phenylacetylene, mediated by Pd(PPh3)2Cl2 in the presence of a CuI co-catalyst, have been investigated in detail. The concentration of Pd dramatically influences the product yield, with lower Pd-loadings favouring higher conversions and purer cross-coupled product. A post reaction time-dependence in product conversion is seen in samples quenched solely on silica-gel (eluted with CH2Cl2). The effect is mirrored in reactions employing 4-nitro-bromobenzene (14) and to a lesser extent (E) and (Z)-ethyl 3-iodo-2-propenonate (16) under similar conditions. A more efficient quenching system (using excess dppe) has been developed to enable accurate determinations in product conversions. Alternatively, solvent and base (Et3N) removal in vacuo, or quench with saturated aqueous ammonium chloride, prevents further turnover in Sonogashira coupling. An ESI-MS study on samples eluted through silica was undertaken to probe the nature of the soluble Pd/Cu species. The Sonogashira cross-coupling of 4-chloro- and 6-chloro-2-pyrone (18 and 20, respectively) has further been investigated. The former undergoes successful coupling, however the latter decomposes in polar aprotic and protic solvents under standard conditions, through a chlorine substitution process, making Pd-mediated reactions problematic.
- Fairlamb, Ian J. S.,Lee, Adam F.,Loe-Mie, Faidjiba E. M.,Niemel?, Elina H.,O'Brien, Ciara T.,Whitwood, Adrian C.
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p. 9827 - 9838
(2007/10/03)
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- Copper-catalyzed synthesis of 1,3-enynes
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We report a copper(I)-catalyzed procedure for the synthesis of 1,3-enynes. This method affords a variety of enynes in good to excellent yields. This method can tolerate a variety of functional groups, does not require the use of expensive additives, and is palladium-free.
- Bates, Craig G.,Saejueng, Pranorm,Venkataraman
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p. 1441 - 1444
(2007/10/03)
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