- Oxidative methoxycarbonylation of propyne and allene with carbon monoxide and methanol in the presence of copper-palladium catalyst
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A direct oxidative methoxycarbonylation of propyne with carbon monoxide in methanol medium in the presence of copper-palladium catalytic system results in methyl 2-butynoate in 18-31% yield. Depending on reaction conditions allene provides either a mixture of methyl 2-(chloromethyl)acrylate and methyl 2-(methoxymethyl)acrylate (~3-4:1) in overall yield 16-23%, or methyl 2-(methoxymethyl)acrylate in 19% yield.
- Mal'kina,Kudyakova,Nosyreva,Afonin,Trofimov
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Read Online
- Covalent Adaptable Networks with Tunable Exchange Rates Based on Reversible Thiol–yne Cross-Linking
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The design of covalent adaptable networks (CANs) relies on the ability to trigger the rearrangement of bonds within a polymer network. Simple activated alkynes are now used as versatile reversible cross-linkers for thiols. The click-like thiol–yne cross-linking reaction readily enables network synthesis from polythiols through a double Michael addition with a reversible and tunable second addition step. The resulting thioacetal cross-linking moieties are robust but dynamic linkages. A series of different activated alkynes have been synthesized and systematically probed for their ability to produce dynamic thioacetal linkages, both in kinetic studies of small molecule models, as well as in stress relaxation and creep measurements on thiol–yne-based CANs. The results are further rationalized by DFT calculations, showing that the bond exchange rates can be significantly influenced by the choice of the activated alkyne cross-linker.
- Du Prez, Filip E.,Guerre, Marc,Maes, Diederick,Unal, Kamil,Van Herck, Niels,Winne, Johan M.
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supporting information
p. 3609 - 3617
(2020/02/04)
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- Stereoselective Synthesis of the C1-C22 Carbon Framework of (-)-Amphidinolide K
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Two stereoselective routes to the C7-C22 subunit of amphidinolide K are disclosed. Jacobsen's hydrolytic kinetic resolution and Sharpless' asymmetric dihydroxylation reactions have been employed for the construction of the tetrahydrofuran ring. The C10-C1
- Chandankar, Somnath S.,Raghavan, Sadagopan
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p. 9584 - 9602
(2019/09/06)
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- Spectroscopy and Photochemistry of Triplet 1,3-Dimethylpropynylidene (MeC3Me)
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Photolysis (λ > 472 nm) of 2-diazo-3-pentyne (11) affords triplet 1,3-dimethylpropynylidene (MeC3Me, 33), which was characterized spectroscopically in cryogenic matrices. The infrared, electronic absorption, and electron paramagnetic resonance spectra of MeC3Me (33) are compared with those of the parent system (HC3H) to ascertain the effect of alkyl substituents on delocalized carbon chains of this type. Quantum chemical calculations (CCSD(T)/ANO1) predict an unsymmetrical equilibrium structure for triplet MeC3Me (33), but they also reveal a very shallow potential energy surface. The experimental IR spectrum of triplet MeC3Me (33) is best interpreted in terms of a quasilinear, axially symmetric structure. EPR spectra yield zero-field splitting parameters that are typical for triplet carbenes with axial symmetry (|D/hc| = 0.63 cm-1, |E/hc| = β 0 cm-1), while theoretical analysis suggests that the methyl substituents confer significant spin polarization to the carbon chain. Upon irradiation into the near-UV electronic absorption (λmax 350 nm), MeC3Me (33) undergoes 1,2-hydrogen migration to yield pent-1-en-3-yne (4), a photochemical reaction that is typical of carbenes bearing a methyl substituent. This facile process apparently precludes photoisomerization to other interesting C5H6 isomers, in contrast to the rich photochemistry of the parent C3H2 system.
- Knezz, Stephanie N.,Waltz, Terese A.,Haenni, Benjamin C.,Burrmann, Nicola J.,McMahon, Robert J.
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p. 12596 - 12604
(2016/10/07)
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- CARM1 INHIBITORS AND USES THEREOF
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Provided herein are compounds of Formula (I): and pharmaceutically acceptable salts thereof, and pharmaceutical compositions thereof; wherein X, R1, R1a, R2a, R2b, R2c, R2d, are as defined herein, and Ring HET is a 6-membered monocyclic heteroaryl ring system of Formula: wherein L2, R13, G8, G10, G11, and G12 are as defined herein. Compounds of the present invention are useful for inhibiting CARMl activity. Methods of using the compounds for treating CARMl -mediated disorders are also described.
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Paragraph 00343
(2016/04/09)
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- Total synthesis of hematoporphyrin and protoporphyrin; A conceptually new approach
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The total synthesis of protoporphyrin IX and its disodium salt using a new alternative method to the classical MacDonald condensation is reported. The key step is the reaction of the new unsymmetrical diiodo dipyrrylmethane 1 with the known dipyrrylmethane 2. Coupling of the two fragments leads directly to porphyrin 3 without the need of an oxidizing agent. The new methodology is well suited for the synthesis of protoporphyrin IX derivatives on a multi-100 g scale in good quality without the need for chromatography. Furthermore, these preparations are completely free of any contaminant of animal origin, which represents a real improvement in the manufacturing of protoporphyrin IX derivatives. Schweizerische Chemische Gesellschaft.
- Martin, Pierre,Mueller, Markus,Flubacher, Dietmar,Boudier, Andreas,Spielvogel, Dirk
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p. 204 - 206
(2013/07/05)
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- Total synthesis of carolacton, a highly potent biofilm inhibitor
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Metals are the key players in the synthesis of caralacton, a strong inhibitor of bacterial biofilms. The total synthesis is based on several metal-mediated key transformations such as the Ley and the Duthaler-Hafner aldol reactions, the Marshall reaction and Breit's substitution, as well as the Nozaki-Hiyama-Kishi and Negishi-Fu C-C coupling reactions. Copyright
- Schmidt, Thomas,Kirschning, Andreas
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supporting information; experimental part
p. 1063 - 1066
(2012/03/11)
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- Palladium(II)-catalyzed dicarboxymethylation of chiral allylic alcohols: Chirality transfer affording optically active diesters containing three contiguous chiral centers
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This manuscript describes the extension of Stille's palladium-catalyzed olefin dicarbonylation reaction to chiral allylic alcohols with chirality transfer to afford the corresponding chiral alcohol functionalized with bis-carbomethoxy esters, containing three contiguous chiral centers, in good to excellent diastereoselectivities (78-98%).
- Hamed, Othman,Henry, Patrick M.,Becker, Daniel P.
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supporting information; experimental part
p. 3514 - 3517
(2010/09/05)
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- Catalytic enantioselective construction of β-quaternary carbons via a conjugate addition of cyanide to β,β-disubstituted α,β-unsaturated carbonyl compounds
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The first general catalytic enantioselective conjugate addition of cyanide to β, β-disubstituted α,β-unsaturated ketones and N-acylpyrroles was developed using a strontium catalyst derived from Sr(O iPr)2 and new chiral ligand 5. The reaction exhibited excellent enantioselectivity and a wide substrate scope using 0.5-10 mol % catalyst. 1,4-Adducts containing β-quaternary carbons were exclusively produced over 1,2-adducts. ESI-MS analysis of the strontium catalyst indicated that the active catalyst was a trimetallic Sr/5 = 3:5 complex. The exclusive 1,4-selectivity was partly due to the ability of the strontium complex to promote both a retro-cyanation reaction from the 1,2-adducts and highly enantioselective conjugate cyanation.
- Tanaka, Yuta,Kanai, Motomu,Shibasaki, Masakatsu
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supporting information; experimental part
p. 8862 - 8863
(2010/08/21)
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- Total synthesis of hematoporphyrin and protoporphyrin: A conceptually new approach
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The total synthesis of protoporphyrin IX and its disodium salt using a new alternative method to the classical MacDonald condensation is reported. The key step is the reaction of the new unsymmetrical diiodo dipyrrylmethane 1 with the known dipyrrylmethane 2. Coupling of the two fragments leads directly to porphyrin 3 without the need of an oxidizing agent. The new methodology is well suited for the synthesis of protoporphyrin IX derivatives on a multi 100 g scale in good quality without the need for chromatography. Furthermore, these preparations are completely free of any contaminant of animal origin, which represents a real improvement in the manufacturing of protoporphyrin IX derivatives.
- Martin, Pierre,Mueller, Markus,Flubacher, Dietmar,Boudier, Andreas,Blaser, Hans-Ulrich,Spielvogel, Dirk
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experimental part
p. 799 - 804
(2011/03/19)
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- Stereoselective synthesis of erythronolide A via nitrile oxide cycloadditions and related studies
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(Chemical Equation Presented) An expeditious synthesis of erythronolide A is documented. Key steps of the approach include two magnesium-mediated nitrile oxide cycloadditions, a chelation-controlled Grignard reaction, and a Sharpless asymmetric dihydroxylation. 2009 American Chemical Society.
- Muri, Dieter,Carreira, Erick M.
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experimental part
p. 8695 - 8712
(2010/01/15)
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- Process For Preparing Porphyrin Derivatives, Such As Protoporphyrin (IX) And Synthesis Intermediates
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The present invention relates to a process for preparing a porphyrin of formula (I), optionally in the form of a salt with an alkali metal and/or in the form of a metal complex: in which: R and R′ are as defined in claim 1, comprising: a step of condensation, in an acidic medium, between a dipyrromethane of formula (II): in which R′b is as defined above for (I), and a dipyrromethane of formula (III): in which R″ is as defined in claim 1, and also the compounds of formula (III).
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Page/Page column 12; 17
(2008/12/07)
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- Total synthesis of 2′-O-methylmyxalamide D and (6E)-2′-O- methylmyxalamide D
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Hetero-bis-metalated 1,3,5-hexatrienes are employed in the linchpin coupling of synthetic fragments for the convergent construction of the central pentaene of the antifungal agent 2′-O-methylmyxalamide D and its (6E) isomer. Sequential Stille and Suzuki-Miyaura couplings interpolate the boron/tin triene into the pentaene chain. The total synthesis of O-methylmyxalamide D and its (6E) isomer was accomplished efficiently. Copyright
- Coleman, Robert S.,Lu, Xiaoling,Modolo, Isabelle
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p. 3826 - 3827
(2008/02/02)
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- Kinetic resolution of 1,2-diols through highly site- and enantioselective catalytic silylation
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(Chemical Equation Presented) Resolved to silylate: A chiral silylation catalyst is used for kinetic resolution of three classes of acyclic 1,2-diols. The catalyst differentiates, with excellent precision, between the two hydroxy groups of a substrate. The majority of the diols, obtained in high enantiomeric purity, cannot be accessed with similar stereochemical purity through catalytic asymmetric dihydroxylation.
- Zhao, Yu,Mitra, Aurpon W.,Hoveyda, Amir H.,Snapper, Marc L.
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p. 8471 - 8474
(2008/09/18)
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- Studies on the synthesis of Richardianidin-1 via the tautomer-arrested annulation of Fischer carbene complexes
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A strategy for the synthesis of richardianidin-1 is evaluated which has as its key step the tautomer-arrested annulation of chromium-carbene complexes. Both inter- and intramolecular variations of the strategy are examined. The intramolecular reaction involves the tethering of the alkyne to the oxygen stabilizing substituent of the carbene carbon. The outcome of the intramolecular tautomer-arrested annulation was found to be highly dependent on the nature of the tether and the on the type of substituent on the alkyne. The product distribution from these reactions included the desired hydrindenone resulting from tautomer-arrested annulation, a naphthalenedione, and a spirocyclohexadienone. The latter two products result from CO insertion prior to cyclization. The optimal tether length for the tautomer-arrested product is four atoms between the alkyne and the carbene carbon. The yields for the intramolecular reaction dropped significantly for a substituent on the alkyne terminus that was larger than a methyl group and this was not suitable for a synthesis of richardianidin-1. Initial studies on the intermolecular tautomer-arrested annulation focused on the regioselectivity of alkyne incorporation. The reaction with isopropyl(methyl)acetylene gives a single regioisomer and reveals that the tautomer-arrested annulation is more regioselective than the normal benzannulation. Furthermore, the intermolecular reaction is more tolerant of larger substituents on the terminus of the alkyne. As a result of the studies on the intermolecular tautomer-arrested annulation a suitable alkyne was found that introduces all of the carbons present in the six-membered lactone of richardianidin-1. Georg Thieme Verlag Stuttgart.
- Bos, Mary Ellen,Loncaric, Catherine,Wu, Chunrui,Wulff, William D.
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p. 3679 - 3705
(2008/03/14)
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- Biocatalytic oxidative kinetic resolution of sec-alcohols: Stereocontrol through substrate-modification
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Whole lyophilised cells of Rhodococcus ruber DSM 44541 were employed for the oxidative kinetic resolution of sec-alcohols using acetone as hydrogen acceptor. The enantioselectivity of this process could be controlled effectively by introducing C-C multiple bonds into substrates, which were inefficiently recognised, in particular short-chain (ω-1)-alcohols and (ω-2)-analogs. Thus, the enantioselectivities of rac-2-pentanol (E=16.8) and rac-3-octanol (E=13.3) were significantly improved by introducing a C=C bond adjacent to the alcohol moiety to give racemic (E)-pent-3-en-2-ol and 4-(E)-octen-3-ol, which were resolved with excellent selectivities (E >100 and 50, respectively). In addition, it was found that high stereodifferentiation between the E- and Z-configured double bonds occurred, as the corresponding (Z)-isomers were not converted. Similar selectivity-enhancing effects were observed with acetylenic analogs.
- Stampfer, Wolfgang,Kosjek, Birgit,Faber, Kurt,Kroutil, Wolfgang
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p. 275 - 280
(2007/10/03)
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- PalladiumdD-catalyzed exchange and isomerization reactions. 17. Exchange of chiral allyl alcohols with hydroxide, methoxide, and phenyl at high [Cl-]. Stereochemistry of the wacker reaction
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At high [Cl ] (> 2.0 M), PdCl42- catalyzes the exchange of chiral allylic alcohols with hydroxy, methoxy, and phenyl to give chiral allyl-substituted olefins. With unsymmetrical olefins, isomerization occurs along with exchange. The hydroxyl exchange occurs in aqueous solution while the other exchanges are carried out in methanol solution. At low [Cl-] (0.1 M) oxidation to the corresponding β-hydroxy-, methoxy-, and phenyl-substituted carbonyl compounds occurred. The absolute configurations of the oxidation and exchange products should be the same if the same mode of addition to the Pd(II)-β-complex is operative. The absolute configurations of the oxidation and exchange products for the phenylation reaction were the same, while for hydroxy and methoxy they were different. This result indicates methanol and water must have different stereochemistries of addition at high and low [Cl-]. Thus, previous studies showing anti hydroxypalladation at high [Cl-] are not valid indicators of the stereochemistry at low [Cl-]. If anti addition occurs at high [Cl-], the addition must be syn at low [Cl-].
- Hamed, Othman,Henry, Patrick M.,Thompson, Charles
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p. 7745 - 7750
(2007/10/03)
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- NAD+-dependent (S)-specific secondary alcohol dehydrogenase involved in stereoinversion of 3-pentyn-2-ol catalyzed by Nocardia fusca AKU 2123
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An NAD+-dependent alcohol dehydrogenase was purified to homogeneity from Nocardia fusca AKU 2123. The enzyme catalyzed (S)-specific oxidation of 3-pentyn-2-ol (PYOH), i.e., part of the stereoinversion reaction for the production of (R)-PYOH, which is a valuable chiral building block for pharmaceuticals, from the racemate. The enzyme used a broad variety of secondary alcohols including alkyl alcohols, alkenyl alcohols, acetylenic alcohols, and aromatic alcohols as substrates. The oxidation was (S)-isomer specific in every case. The Km and Vmax for (S)-PYOH and (S)-2-hexanol oxidation were 1.6 mM and 53 μmol/min/mg, and 0.33 mM and 130/μmol/min/mg, respectively. The enzyme also catalyzed stereoselective reduction of carbonyl compounds. (S)-2-Hexanol and ethyl (R)-4-chloro-3-hydroxybutanoate in high optical purity were produced from 2-hexanone and ethyl 4-chloro-3-oxobutanoate by the purified enzyme, respectively. The Km and Vmax for 2-hexanone reduction were 2.5 mM and 260 μmol/min/mg. The enzyme has a relative molecular mass of 150,000 and consists of four identical subunits. The NH2-terminal amino acid sequence of the enzyme shows similarity with those of the carbonyl reductase from Rhodococcus erythropolis and phenylacetaldehyde reductase from Corynebacterium sp.
- Xie, Sheng-Xue,Ogawa, Jun,Shimizu, Sakayu
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p. 1721 - 1729
(2007/10/03)
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- RAMFORD-STEVENS REACTION IN THE SERIES OF 1-ACYL-1-R-CYCLOPROPANES
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Investigation of the relationships governing the carbene decomposition of the monotosylhydrazones of 1-R-1-acylcyclopropanes showed that ?-accepting substituents at the gem position to the carbonyl group increase the stability of the three-membered ring under the conditions of the Bamford-Stevens reaction.This leads to partial suppression of the cyclopropylmethyl-cyclobutene isomerization process and, as a result, to the formation of 1,1-gem-alkenylcyclopropanes and bicyclobutanes.
- Kuznetsova, T. S.,Kozhushkov, S. I.,Gromov, A. V.,Vatlina, L. P.,Kozlovskii, V. I.,Zefirov, N. S.
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p. 256 - 262
(2007/10/02)
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- Phenyl Cations as Reactive Intermediates in the Solvolysis of Dien-in-yl Triflates
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The synthesis, separation, and solvolysis of the stereoisomeric 1,4-dimethyl-1,3-hexadien-5-yn-1-yl triflates 15a - c in various solvents are described.In contrast to the (Z)-isomers 15a - c, the (E)-isomers 15a - c react preferably via an intermediate phenyl cation 16 to give the phenyl ethers 17.Further mechanistic investigations which support the formation of the intermediate phenyl cations 16 are described.The formation of the benzylic derivatives 18 is discussed.
- Holweger, Walter,Hanack, Michael
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p. 3004 - 3020
(2007/10/02)
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- REACTION OF HYDROXY AND CARBONYL COMPOUNDS WITH SULFUR TETRAFLUORIDE. IX. REACTIONS OF ALIPHATIC β-DIKETONES WITH SF4
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Aliphatic β-diketones react with sulfur tetrafluoride to form the corresponding di- and tetrafluoro derivatives and also compounds containing double and triple carbon-carbon bonds.In the reactions of 1,1,1-trifluoro derivatives of β-diketones with sulfur tetrafluoride the acyl fluoride is eliminated, and 1,1,1,2-tetrafluoropropene is obtained.Hexafluoroacetylacetone only forms 3-hydroperfluoro-2-pentene under the influence of sulfur tetrafluoride.
- Stepanov, I. V.,Burmakov, A. I.,Kunshenko, B. V.,Alekseeva, L. A.,Yagupol'skii, L. M.
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p. 244 - 248
(2007/10/02)
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- Cycloelimination of β-Silylethyl Sulphoxides: Alkene, Alkyne, and Vinylsilane-forming Reactions
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The cycloelimination (1)->(3) of trimethylsilyl sulphenate from a β-silylethyl sulphoxide is slightly faster than the corresponding cycloelimination (2)->(3) of sulphenic acid itself.The former type of reaction can be used to form acetylenes (
- Fleming, Ian,Goldhill, Jon,Perry, David A.
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p. 1563 - 1570
(2007/10/02)
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- Vinyl Cations, 35. Mechanisms of Formation of Vinyl Triflates on Treatment of Ketones with Trifluoromethanesulfonic Anhydride
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Alkynones (5) are treated with trifluoromethanesulfonic anhydride in the presence of various bases to give 1-(1-alkynyl)vinyl triflates (6).The mechanisms of formation of vinyl triflates are discussed in detail.
- Hanack, Michael,Hassdenteufel, Juergen R.
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p. 764 - 771
(2007/10/02)
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- PHOTOCHEMICAL CYCLOADDITION OF α,β-ACETYLENIC KETONES WITH SIMPLE OLEFINS
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Irradiation of 3-pentyn-2-one (1) in the presence of tetramethylethylene, isobutylene, and cis- and trans-2-butene leads to vinyldihydrofurans 3, 5, 6, 8, and 9 (Table 1) in a novel photochemical cycloaddition reaction.A related adduct 13 is formed between tetramethylethylene and 5,5-dimethyl-3-hexyn-2-one (2).A mechanism incorporating an initial biradical that closes to a carbene (eqn 3) is proposed to account for these reactions.
- Hussain, Saadat,Agosta, William C.
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p. 3301 - 3306
(2007/10/02)
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- CYCLO-ELIMINATION OF SILYL AND SULPHOXIDE GROUPS IN COMPETITION WITH THE CONVENTIONAL CYCLO-ELIMINATION OF SULPHOXIDES
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The β-silylsulphoxides (2 and 4) undergo a fast syn-elimination to give the alkene (3) and the alkyne (6), respectively; however, when there is a hydrogen α to the silyl group, only hydrogen is lost, and the products are β-silylenones.
- Fleming, Ian,Perry, David A.
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p. 5095 - 5096
(2007/10/02)
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- A CONVENIENT SYNTHESIS OF ACETYLENIC KETONES FROM β-DIKETONES USING α,α-DIFLUOROALKYLAMINES AND FREEZE-DRIED POTASSIUM FLUORIDE
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α,α-Difluoroalkylamines, such as 1-diethylamino-2-chloro-1,1,2-trifluoroethane (1) and 1-diethylamino-1,1,2,3,3,3-hexafluoropropane (2), were found to be useful dehydrating agents for the sysnthesis of acetylenic ketones from β-diketones in the presence o
- Kitazume, Tomoya,Ishikawa, Nobuo
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p. 1327 - 1328
(2007/10/02)
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- VINYL CATIONS 33: 1-ALKENE-3-YNE-2-YL TRIFLATES, PRECURSORS OF TRIPLE BOND STABILIZED VINYL CATIONS-SYNTHESIS AND FIRST SOLVOLYTIC STUDIES.
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The α-alkynyl vinyl triflates (3) are synthesized and the solvolyses reactions studied in different solvents.The solvolysis products and kinetic data indicate, that the hitherto unknown triple bond stabilized vinyl cation 2a 2b is formed as an intermediate.
- Hassdenteufel, Juergen Rolf,Hanack, Michael
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p. 503 - 506
(2007/10/02)
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