Palladium-Catalyzed Alkynylation

Negishi, E.; Anastasia, Luigi

doi:10.1021/cr020377i

Cited by 1,198 publications

(495 citation statements)

References 262 publications

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“…19 The synthesis was initiated by acid catalyzed esterification of biotin. Selective reduction of the ester 2 was accomplished using diisobutylaluminum hydride (DIBAL) at -78 °C, affording alcohol 3 in 96% yield.…”

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confidence: 99%

Synthesis of a Biotin-Derived Alkyne for Pd-Catalyzed Coupling Reactions

2006

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An efficient synthesis of a terminal alkyne derived from d-biotin was developed to provide an alternative for carboxylbased biotinylation. This approach was illustrated by the preparation of alkyne-and alkene-linked phenylalanine derivatives using palladium-catalyzed Sonogashira and Oh methodology. (Strept)avidin binding was observed using soluble and immobilized receptors. These results demonstrate the applicability of carbon-linked biotin derivatives for use in affinity-based purification and bioanalytical applications.The interaction between biotin (Vitamin H) 1 and the glycoprotein avidin is one of the strongest noncovalent associations known (K a ∼2.5 X 10 15 M -1 ). Avidin is tetrameric and each subunit is capable of binding a biotin ligand. The high binding affinity and exceptionally slow dissociation rates of biotin results from a network of hydrogen bonds between receptor and the heterocyclic 7-oxo-3-thia-6,8-diazabicyclo[3.3.0]oct-4-yl ligand. The ureido nitrogens of biotin form hydrogen bonds with Thr35 and Asn118, the oxygen contacts Ser16 and Tyr33. Additional hydrogen bonding occurs between the biotin carboxylic acid and avidin residues Ala39, Thr40 and Ser75. The hydrophobic tetrahydrothiophene interacts with Phe79, Trp97, and Trp110. 1 Avidin and the related tetrameric protein streptavidin share ∼33% conserved amino acids and strong biotin binding affinity (K a ∼ 1.0 X 10 12 M -1 ). 2 Specific interactions include hydrogen bonding between biotin urea nitrogens with Ser45 and Asp128 and oxygen contacts with Asn23, Ser27 and Tyr43. Interactions also exist between Asn49 and Ser88 and the biotin carboxylic acid group. This network of hydrogen bonding in conjunction with hydrophobic interactions with four Trp residues (Trp 79, 92, 108, 120) and the tetrahydrothiophene result in high binding affinity. 3 * jarterbu@nmsu.edu Supporting Information Available: General methods, experimental details, copies of 1 H-NMR and 13 C-NMR spectra of compounds 1-3, 5-7, 9, 10, 12, 13, and HABA titration curves. Several structural modifications have been described to prevent biotinidase cleavage however, these derivatives exhibit increased dissociation rates from (strept)avidin. Biotin amide derivatives containing a small α-substituent have provided the most effective balance of biotinidase stability and (strept)avidin affinity. 14 Both N-methylation of the biotinamide linkage 15 and homologation of the valeric acid chain provided increased resistance to cleavage 16 as did replacement of the biotinamide connection with thiourea. Unfortunately, increased dissociation rates were observed with all of these linkagemodified derivatives. 17 NIH Public AccessWe have been interested in developing biotin conjugates of hydrophobic receptor ligands for affinity purification. Available biotin-coupling reagents are not suitable for derivatizing compounds that lack reactive functional groups such as amine, carboxylate or thiol. The installation of polar substituents on a hydrophobic receptor substrate is possible but may d...

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Synthesis of a Biotin-Derived Alkyne for Pd-Catalyzed Coupling Reactions

2006

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“…26) It has been well established that the reactivity of aryl halides to Pd(0) depends upon the electronic nature of the substituents on the aryl group and the halides bearing an electron-withdrawing substituent are more reactive than those having an electron-donating group. 29,30) Successive transmetallation of the intermediates (E) with another ethynylstibane led to the formation of diethynyl-Pd(II) complex (F) and the following reductive elimination afforded 1,3-diynes (5) (Route II-2). Formation of the direct crosscoupling products (4) would be also possible via the intermediate (D) caused from reaction of the intermediate (E) with aryl iodide (Route II-1).…”

Section: Resultsmentioning

confidence: 99%

Carbonylative Cross-Coupling Reaction of Ethynylstibane with Aryl Iodides

Kakusawa

Kurita

2006

CHEMICAL & PHARMACEUTICAL BULLETIN

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Recent remarkable development of novel transmetallating agents for cross-coupling reactions has been fascinating to many synthetic chemists because of its high reliability and wide applicability for C-C, C-O and C-N bond forming reaction.1,2) Especially, investigations on novel coupling agents involving typical heavier elements such as In, 3,4) Si, 5-7) Bi, 8,9) and Ge 10,11) attract much attention not only of heteroatom chemists, but also of synthetic chemists. These transmetallating agents can easily be activated and coupled with various organic halides under mild condition, based on a hypervalent strategy.12,13) One useful application of these transmetallating agents is carbonylative cross-coupling reaction which leads to the formation of unsymmetrical ketones in one-pot operation from an appropriate transmetallating agent and organic halides under carbon monoxide (CO) atmosphere. [14][15][16][17][18][19][20][21] The organoantimony(III) [Sb(III)] compounds are relatively stable and can be prepared easily compared to organoantimony(V) and hypervalent antimony compounds. The facile access of Sb(III) compounds stimulated us to employ them as practical organic reagents. We have recently explored the palladium-catalyzed cross-coupling reaction of Sb(III) compounds with organic halides and their versatile applicability, e.g. ethynylstibanes (1) were coupled with acyl chlorides, vinyl iodides and aryl iodides to give ethynylketones, 1,3-enynes, and arylacetylens, respectively. 22,23) We also demonstrated that these reactions were accelerated with microwave irradiation. 24) A mild and efficient Sb(III)-mediated cross-coupling reaction was also achieved with ethynyland ary-1,5-azastibocienes bearing an intramolecular N … Sb non-bonding interaction. 25,26) As an extension of the versatility of Sb(III) compounds as a transmetallating agent, we investigated the cross-coupling reaction of ethynylstibanes with aryl iodides under CO atmosphere. In the present reaction, the yield of the carbonylated coupling products is sensitive to the nature of the Pd catalyst, and superior results were obtained by using a monodentate phosphine-ligated Pd catalyst. It also appeared that a variety of unsymmetrical ethynyl ketones could be synthesized in excellent yield under high pressure condition (CO, 20 atm) even in the reactions with electron-deficient aryl iodides which usually gave inferior results due to their tendency to undergo decarbonylation. Results and DiscussionPd-Catalyzed Carbonylative Cross-Coupling Reaction of Ethynylstibane with Aryl Iodides under CO Atmosphere In order to optimize the reaction conditions, we initially attempted the reaction of ethynyldiphenylstibane (1) and iodobezene (2a) under atmospheric CO pressure using a variety of solvents in the presence of 5 mol% of various palladium (Pd) catalysts (Table 1). The reaction did not proceed in THF or benzene which was often employed for carbonylative cross-coupling with a variety of organometallic compounds.2,14-16,18,21) For direct cross-coupling reaction of 1 and...

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“…[1][2][3] In addition, substituted alkynes bearing carboxylic group are useful intermediates which can be reduced for the preparation of some simplified hybrid inhibitors, 4 and also may act as trapping sites to the metal ions. 5 In the traditional strategy, these compounds were synthesized by the esterification of halogenated aromatic acids, followed by Sonogashira coupling between the halogenated aromatic carboxylic esters and terminal alkynes and then subsequently hydrolysis of the coupling products to release the carboxylic group.…”

Section: Introductionmentioning

confidence: 99%

Protecting-group-free synthesis of carboxylic group substituted alkynes by Sonogashira coupling in neat water

Zhu¹,

Wang²,

Bai³

et al. 2011

Arkivoc

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An effective, economic and green synthesis of carboxylic group substituted alkynes by Sonogashira coupling of halogenated aromatic acids with phenylacetylene has been developed. The coupling reaction proceeds well using Pd(OAc)2/TPPTS-CuI as catalyst with K2CO3 as base in water. It is worth noting that this procedure avoids the protection/deprotection steps of carboxylic group and obtains the title compounds in good to excellent yields.

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Palladium-Catalyzed Alkynylation

Cited by 1,198 publications

References 262 publications

Synthesis of a Biotin-Derived Alkyne for Pd-Catalyzed Coupling Reactions

Synthesis of a Biotin-Derived Alkyne for Pd-Catalyzed Coupling Reactions

Carbonylative Cross-Coupling Reaction of Ethynylstibane with Aryl Iodides

Protecting-group-free synthesis of carboxylic group substituted alkynes by Sonogashira coupling in neat water

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