- Electrochemical selective incorporation of CO2 into terminal alkynes and diynes
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Electrochemical incorporation of CO2 into terminal alkynes and diynes on silver cathodes occurred selectively, to afford monocarboxylic acid derivatives in good yields. The electrolyses were carried out in one-compartment cells fitted with magnesium anodes, under mild conditions.
- Ko?ster, Frank,Dinjus, Erkhardt,Din?ach, Elisabet
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- Cobalt(III)-Catalyzed Construction of Benzofurans, Benzofuranones and One-Pot Orthogonal C?H Functionalizations to Access Polysubstituted Benzofurans
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Benzofuran and benzofuranone derivatives have been synthesized through exclusive 5-exo-dig intramolecular hydroarylation using the amide-directed, cost-effective, high-valent Cp*CoIII-catalytic system. Challenging one-pot, orthogonal C?H functionalizations using two different electrophiles are also reported to afford polysubstituted benzofurans. Several valuable functional group interconversions along with removal of the amide directing group provide a route to access several diversely functionalized benzofurans. The mechanistic study suggests a reversible cobaltation step is operative here. (Figure presented.).
- Bera, Sourav Sekhar,Debbarma, Suvankar,Jana, Sripati,Maji, Modhu Sudan
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supporting information
p. 2204 - 2210
(2018/06/07)
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- Understanding the mechanism of transition metal-free: Anti addition to alkynes: The selenoboration case
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The stereoselective anti-addition of selenoboranes to α,β-acetylenic esters and amides was achieved in a transition metal-free context using catalytic amounts of PCy3. The reaction provides anti-3,4-selenoboration with concomitant delivery of α-vinyl selenides by protodeboronation with MeOH. Interestingly, in the absence of phosphine the selenoboration switches towards the formation of β-vinyl selenides. Theoretical calculations rationalize the regio- and stereoselectivity of the reaction by discovering a new mechanism for the anti-3,4-selenoboration. While the selenoborane is activated via the "push-pull" effect of B, the phosphine interacts with the β position of the alkynoate switching the polarity of the triple bond and favoring 1,3-selenoboration which provides the α-addition of the selenyl group. Then, the autocatalytic action of a second selenoborane reagent, which coordinates to the phosphorus ylide intermediate, determines the stereoselectivity and completes the catalytic process. Finally, the comparison of selenoborane reagents with diboranes and silaboranes, which have exhibited analogous reactivity, shows that the selenium moiety has a larger nucleophilic character favoring the performance of the reaction under mild conditions.
- García-López, Diego,Civit, Marc G.,Vogels, Christopher M.,Ricart, Josep M.,Westcott, Stephen A.,Fernández, Elena,Carbó, Jorge J.
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p. 3617 - 3628
(2018/07/29)
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- Copper-Catalyzed Domino Synthesis of Benzo[4,5]imidazo[1,2-a]pyrimidin-4(10H)-ones using Cyanamide as a Building Block
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An efficient and practical copper-catalyzed domino synthesis of benzo[4,5]imidazo[1,2-a]pyrimidin-4(10H)-ones has been developed. The protocol uses N-(2-halophenyl)-3-alkylpropiolamides and cyanamide as the starting materials, inexpensive copper(I) iodide and pipecolinic acid as the catalyst and ligand, and the corresponding products were obtained in moderate to good yields.
- Lou, Zhenbang,Wu, Xudong,Yang, Haijun,Zhu, Changjin,Fu, Hua
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supporting information
p. 3961 - 3968
(2016/01/25)
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- A palladium nanoparticle-nanomicelle combination for the stereo-selective semihydrogenation of alkynes in water at room temperature
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The addition of NaBH4 to Pd(OAc) 2 in water containing nanomicelles leads to the generation of H2 and Pd nanoparticles. Subsequent reduction of disubstituted alkynes affords Z-alkenes in high yields. These reactions are general, take place in water at ambient temperatures, and offer recycling of the aqueous reaction mixture along with low overall E Factors.
- Slack, Eric D.,Gabriel, Christopher M.,Lipshutz, Bruce H.
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supporting information
p. 14051 - 14054
(2015/02/19)
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- PROCESS FOR PREPARING A PROPIOLIC ACID OR A DERIVATIVE THEREOF
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The invention relates to a process for preparing a propiolic acid or a derivative thereof by reacting a terminal alkyne with carbon dioxide, which comprises performing the reaction in the presence of a base and a copper complex, especially a copper (I) complex having at least one ligand, at least one of the ligands of the copper complex being selected from monodentate ligands which have an aminic or iminic nitrogen atom capable of coordination with copper, and polydentate ligands having at least two atoms or atom groups which are capable of simultaneous coordination with copper and are selected from nitrogen, oxygen, sulfur, phosphorus and carbene carbon.
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Paragraph 0138
(2014/02/15)
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- CuI/Pd0 cooperative dual catalysis: Tunable stereoselective construction of tetra-substituted alkenes
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This paper describes a tunable and stereoselective dual catalytic system that uses copper and palladium reagents. This cooperative silylcupration and palladium-catalyzed allylation readily affords trisubstituted alkenylsilanes. Fine-tuning the reaction conditions allows selective access to one stereoisomer over the other. This new methodology tolerates different substituents on both coupling partners with high levels of stereoselectivity. The one-pot reaction involving a CuI/Pd0 cooperative dual catalyst directly addresses the need to develop more time-efficient and less-wasteful synthetic pathways.
- Vercruysse, Sebastien,Cornelissen, Loic,Nahra, Fady,Collard, Laurent,Riant, Olivier
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supporting information
p. 1834 - 1838
(2014/03/21)
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- Copper(II)-catalyzed silylation of activated alkynes in water: Diastereodivergent access to E- or Z-β-silyl-α,β-unsaturated carbonyl and carboxyl compounds
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Copper(II)-catalyzed silylation of substituted alkynylcarbonyl compounds was investigated. Through the activation of Me2PhSiBpin in water at room temperature and open atmosphere, vinylsilanes conjugated to carbonyl groups are synthesized in high yield. A surprising diastereodivergent access to olefin geometry was discovered using a silyl conjugate addition strategy: aldehydes and ketones were Z selective while esters and amides were exclusively transformed into the E products. Dial a diastereomer: The title reaction proceeds through the activation of Me2PhSiBpin in water at room temperature and open atmosphere to produce high yields of vinylsilanes conjugated to carbonyl groups. A surprising diastereodivergent access to olefin geometry was discovered using this silyl conjugate addition strategy: aldehydes were Z selective while esters and amides exclusively delivered the E-configured products.
- Calderone, Joseph A.,Santos, Webster L.
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supporting information
p. 4154 - 4158
(2014/05/06)
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- Stereoselective silylcupration of conjugated alkynes in water at room temperature
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Micellar catalysis enables copper-catalyzed silylcupration of a variety of electron-deficient alkynes, thereby providing access to isomerically pure E- or Z-β-silyl-substituted carbonyl derivatives. These reactions take place in minutes, afford high yields and stereoselectivity, and are especially tolerant of functional groups present in the substrates. The aqueous reaction medium has been successfully recycled several times, and a substrate/catalyst ratio of 10,000:1 has been documented for this methodology. Fast, cheap, and green: Micellar catalysis enables the selective construction of a variety β-silyl-substituted carbonyl derivatives under mild aqueous conditions. The reaction is catalyzed by low levels of CuI, is compatible with numerous electron-withdrawing groups, affords high yields, and provides opportunities for scale-up and recycling of the reaction medium. The environmental impact, as measured by E Factors, is very low.
- Linstadt, Roscoe T. H.,Peterson, Carl A.,Lippincott, Daniel J.,Jette, Carina I.,Lipshutz, Bruce H.
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supporting information
p. 4159 - 4163
(2014/05/06)
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- A new strategy for the synthesis of chiral β-alkynyl esters via sequential palladium and copper catalysis
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A new strategy for the synthesis of chiral β-alkynyl esters which relies on sequential Pd and Cu catalysis is reported. Terminal alkynes bearing aryl, alkyl, and silyl groups can be employed without prior activation yielding a wide range of important chiral building blocks. The reaction sequence utilizes a robust Pd(II)-catalyzed hydroalkynylation of ynoates with terminal alkynes providing geometrically pure ynenoates which are readily reduced by CuH. In contrast to previous reports, where additions to ynenoates proceed with marginal preference for the 1,6-pathway, this conjugate reduction occurs with high 1,4-selectivity yielding β-alkynyl esters with excellent levels of enantioselectivity. Importantly, the method tolerates a wide range of functionality, including allylic carbonates and carbamates, and thus allows for rapid elaboration of the β-alkynyl esters into a variety of chiral, substituted heterocycles.
- Trost, Barry M.,Taft, Benjamin R.,Masters, James T.,Lumb, Jean-Philip
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supporting information; experimental part
p. 8502 - 8505
(2011/07/08)
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- Synthesis of 2-acetylenic carboxylic acids, 1-sulfinyl and 1-sulfonyl- 2-ketones from 2-acetylenic phenyl sulfides
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Monochlorination at the 1-position with sulfuryl chloride, followed by methanolysis converted 2-acetylenic phenyl sulfides into 1-methoxy-2- acetylenic phenyl sulfides. Oxidation with chromic acid gave 2-acetylenic carboxylic acids. Oxidation of 2-acetylenic phenyl sulfides with Oxone and hydrogen peroxide in acetic acid gave the corresponding sulfoxides and sulfones respectively. Diethylamine addition to the triple bond produced enamines which were hydrolyzed with aqueous hydrochloric acid to the corresponding 1-sulfinyl and 1-sulfonyl-2-ketones.
- Fortes, Carlos C.,Garrote, Clevia F.D.
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p. 2993 - 3026
(2007/10/03)
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- Platinum Complex Catalyzed Carbonylation of Organic Iodides: Effective Carbonylation of Organic Iodides Having β-Hydrogens on Saturated sp3 Carbons
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Dichlorobis(triphenylphosphine)platinum(II) is an effective catalyst precursor for the carbonylation of organic iodides having β-hydrogens on saturated sp3 carbons.The carbonylation under carbon monoxide pressure in the presence of alcohol gives esters, and aldehydes are obtained by the reaction under carbon monoxide and hydrogen pressure.Thus, 1-iodohexane is carbonylated to methyl heptanoate in 79percent yield in the presence of methanol at 120 deg C under 70 kg cm-2 of initial carbon monoxide pressure.Heptanal is formed in 86percent yield from 1-iodohexane at 120 deg Cunder carbon monoxide (50 kg cm-2) and hydrogen (50 kg cm-2).Alkenyl und alkynyl iodides are also smoothly carbonylated in the presence of alcohol into the corresponding esters without reduction of unsaturated bonds.
- Takeuchi, Ryo,Tsuji, Yasushi,Fujita, Masayuki,Kondo, Teruyuki,Watanabe, Yoshihisa
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p. 1831 - 1836
(2007/10/02)
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- Palladium(II) Chloride Catalyzed Carbonylation of Organic Tellurides with Carbon Monoxide
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Various organic tellurides react with carbon monoxide (1 atm) at room temperature in methanol in the presence of PdCl2 and Et3N to afford the corresponding methyl carboxylates in good to excellent yields.The reaction is catalytic in PdCl2 when a suitable reoxidant such as CuCl2, CuCl/O2, FeCl3 or Ce(NH4)2(NO3)6 is present.The combination of this carbonylation with phenyltellurenylation of arylacetylenes and propargylic alcohols makes it possible to prepare ring-substituted cis-methyl cinnamates and Δα,β-butenolides, respectively.Both monomeric and dimeric palladium complexes, (Ph2Te)2PdCl2 and 2, react readily with CO to give a high yield of methyl benzoate.The key step of the present carbonylation is proposed to be the migration of an organic moiety from Te to Pd (transmetalation) in organic telluride-PdCl2 complexes, presumably formed in situ, to afford organopalladium compounds.
- Ohe, Kouichi,Takahashi, Hidetaka,Uemura, Sakae,Sugita, Nobuyuki
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p. 4859 - 4863
(2007/10/02)
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- PALLADIUM-CATALYZED ACYLATION OF ORGANOZINCS AND OTHER ORGANOMETALLICS AS A CONVENIENT ROUTE TO KETONES
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The reaction of organozincs with acyl chlorides catalyzed by palladium-phosphine complexes, e.g., Pd(PPh3)4, provides a highly general and convinient route to ketones.
- Negishi, Ei-ichi,Bagheri, Vahid,Chatterjee, Sugata,Luo, Fen-Tair,Miller, Joseph A.,Stoll, A. Timothy
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p. 5181 - 5184
(2007/10/02)
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