- Palladium-catalyzed oxidative alkynylation of alkenes via C-C bond cleavage under oxygen atmosphere
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(Matrix presented) Palladium-catalyzed oxidative alkynylation of alkenes using tert-propargylic alcohols as alkynylation reagents via C-C bond cleavage under an oxygen atmosphere affords the corresponding ene-yne compounds.
- Nishimura, Takahiro,Araki, Hitoshi,Maeda, Yasunari,Uemura, Sakae
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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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Read Online
- Synthesis of Ethyl (2E)-5-Phenylpent-2-en-4-ynoate
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An efficient procedure has been developed for the synthesis of ethyl (2E)-5-phenylpent-2-en-4-ynoate by olefination-dehydrohalogenation of (2Z)-2-iodo-3-phenylprop-2-enal prepared by iodination of commercially available cinnamaldehyde.
- Shakhmaev,Sunagatullina, A. Sh.,Ignatishina,Yunusova, E. Yu.,Zorin
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p. 897 - 899
(2019/08/02)
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- Chemo- and Regioselective Synthesis of Alkynyl Cyclobutanes by Visible Light Photocatalysis
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Here is the first visible light catalytic intermolecular cross [2 + 2] cycloaddition of enynes with alkenes to alkynyl cyclobutanes established with good functional group tolerance and high reaction efficiency and selectivity. Detailed studies reveal that
- Zhou, Chao,Lei, Tao,Wei, Xiang-Zhu,Liu, Zan,Chen, Bin,Ramamurthy, Vaidhyanathan,Tung, Chen-Ho,Wu, Li-Zhu
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supporting information
p. 6808 - 6811
(2018/11/21)
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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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- Stereoselective Traceless Borylation–Allenation of Propargylic Epoxides: Dual Role of the Copper Catalyst
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Chiral α-allenols are prepared with high diastereocontrol through an unprecedented and spontaneous β-oxygen elimination of an α-epoxy vinyl boronate. Stochiometric experiments and DFT calculations support a dual role of the copper catalyst, which orchestrates the hydroboration and the syn-elimination step.
- Jarava-Barrera, Carlos,Parra, Alejandro,Amenós, Laura,Arroyo, Ana,Tortosa, Mariola
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supporting information
p. 17478 - 17481
(2017/11/30)
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- Lewis Base Activation of Silyl Acetals: Iridium-Catalyzed Reductive Horner-Wadsworth-Emmons Olefination
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A Lewis base promoted deprotonative pronucleophile addition to silyl acetals has been developed and applied to the iridium-catalyzed reductive Horner-Wadsworth-Emmons (HWE) olefination of esters and the chemoselective reduction of the resulting enoates. Lewis base activation of silyl acetals generates putative pentacoordinate silicate acetals, which fragment into aldehydes, silanes, and alkoxides in situ. Subsequent deprotonative metalation of phosphonate esters followed by HWE with aldehydes furnishes enoates. This operationally convenient, mechanistically unique protocol converts the traditionally challenging aryl, alkenyl, and alkynyl esters to homologated enoates at room temperature within a single vessel.
- Dakarapu, Udaya Sree,Bokka, Apparao,Asgari, Parham,Trog, Gabriela,Hua, Yuanda,Nguyen, Hiep H.,Rahman, Nawal,Jeon, Junha
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supporting information
p. 5792 - 5795
(2015/12/11)
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- A metal-free tandem C-C/C-O bond formation approach to diversely functionalized tetrasubstituted furans
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A novel and efficient method for the synthesis of diversely functionalized furans is developed via DBU-mediated tandem Michael addition/5-exo-dig- cycloisomerization of enynes and keto-methylenes. This [3 + 2]-annulation is operationally simple under metal-free reaction conditions with 100% atom economy and broad substrate scope.
- Reddy, Chada Raji,Reddy, Motatipally Damoder
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p. 106 - 116
(2014/01/17)
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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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- Practical new silyloxy-based alkyne metathesis catalysts with optimized activity and selectivity profiles
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Triphenylsilanolate ligands were found to impart excellent reactivity and outstanding functional group tolerance on molybdenum alkylidyne complexes, which catalyze alkyne metathesis reactions of all sorts. The active species either can be obtained in high yield by adaptation of the established synthesis routes leading to Schrock alkylidynes or can be generated in situ from the molybdenum nitride complex 11, which itself is readily accessible in large quantity from inexpensive sodium molybdate. Complexation of the active silanolate complexes 12 and 24 with 1,10-phenanthroline affords complexes 15 and 25, respectively, which are stable in air for extended periods of time. Although these phenathroline adducts are per se unreactive vis-a-vis alkynes, catalytic activity is conveniently restored upon exposure to MnCl2. Therefore, the practitioner has the choice of different alkyne metathesis (pre)catalysts, which are easy to handle yet broadly applicable and exceedingly tolerant. A host of representative inter- as well as intramolecular alkyne metathesis reactions, including applications to a considerable number of bioactive and, in part, labile natural products, shows the remarkable scope of these new tools. Moreover, it was found that the addition of molecular sieves (5 A ≤ 4 A > 3 A) to the reaction mixture significantly improves the chemical yields while simultaneously increasing the reaction rates. This benefit is ascribed to effective binding of 2-butyne, which is released as the common byproduct in reactions of alkynes bearing a methyl end-cap. Thus, alkyne metatheses can now be performed at ambient temperature with neither the need to apply vacuum to drive the conversion nor recourse to tailor-made substrates. The structures of representative examples of this new generation of alkyne metathesis catalysts in the solid state were determined by X-ray analysis.
- Heppekausen, Johannes,Stade, Robert,Goddard, Richard,Fuerstner, Alois
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supporting information; experimental part
p. 11045 - 11057
(2010/10/02)
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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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- 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 10; 27
(2009/01/24)
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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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- Process development and scale-up of the PPAR agonist NNC 61-4655
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A scalable synthetic route of the nonselective but PPARα-preferring potent PPAR agonist NNC 61-4655 aimed for treatment of type 2 diabetes was developed. The synthetic pathway comprises the convergent synthesis and coupling of the two key intermediates E-5-(chloropent-3-en-1-ynyl)benzene 8 (prepared in a five-step synthesis in 18% overall yield) and (S)-2-ethoxy-3-(4- hydroxyphenyl)propanoic acid isopropyl ester 9. The 2-aminoethanol salt of NNC 61-4655 was selected in a preclinical salt selection program as the appropriate salt form for further development. More than 900 g of NNC 61-4655, 2-aminoethanol was finally synthesized under GMP in 98.7% purity. In comparison to the original medicinal chemistry route, starting from phenylpropargyl aldehyde 1, the overall yield towards NNC 61-4655 could be enhanced from 24 to 37%. An improved scalable two-step synthesis for 8 was developed on a laboratory scale (≥33-35% overall yield) shortly after the GMP batch.
- Deussen, Heinz-Josef,Jeppesen, Lone,Schaerer, Norbert,Junager, Finn,Bentzen, Bjorn,Weber, Beat,Weil, Volker,Mozer, Sandor Josef,Sauerberg, Per
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p. 363 - 371
(2013/09/05)
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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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- New compounds, their preparation and use
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The present invention relates to compounds of formula (I) The compounds are useful in the treatment and/or prevention of conditions mediated by nuclear receptors, in particular the Peroxisome Proliferator-Activated Receptors (PPAR).
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- Process development of a novel non-xanthine adenosine A1 receptor antagonist
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(+)-(R)-1-[(E)-3-(2-phenylpyrazolo[l,5-a]pyridin-3-yl)acryloyl]-2- piperidine ethanol (FK453) is a novel, potent adenosine AI receptor antagonist for the regulation of renal function. The development of a reliable process suitable for large scale manufacture is described. A Horner-Emmons reaction and a 1,3-dipolar cycloaddition were successfully scaled up to afford ethyl (E)-3-(2-phenylpyrazolo[l,5-a]pyridin-3-yl)acryloylate, with excellent regioselectivity and stereoselectivity. Process improvements and optimization of each step permitted elimination of column chromatography, resulting in a straightforward, practical synthesis of FK453.
- Zanka, Atsuhiko,Uematsu, Ryoichi,Morinaga, Yasuhiro,Yasuda, Hironobu,Yamazaki, Hiroshi
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p. 389 - 393
(2013/09/08)
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- Synthesis of Allenes by 1,6-Addition of Organocuprates to Polarized Enynes
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Ten β-allenic esters, ketones, and thioesters 15 bearing alkyl, alkenyl, aryl, and trimethylsilyl groups are synthesized in 57-85percent yield by 1,6-addition of organocuprates to polarized enynes 10.The dependence of the regioselectivity of the protonation of the allenyl enolate intermediate 7 on the protonating agent is studied; pure allenes are obtained by quenching the intermediate with pivalic acid at -80 deg C.The method is applied in a short synthesis of pseudoionone (18).
- Krause, Norbert
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p. 2173 - 2180
(2007/10/02)
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