The palladium(o) catalyzed synthesis of vinylnitriles from vinyl halides

Yamamura, Kimiaki; Murahashi, Shun‐Ichi

doi:10.1016/s0040-4039(01)83527-9

Cited by 65 publications

(12 citation statements)

References 7 publications

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“…The installation of a cyano group at the 5-position would lead to a push–pull system that could open new synthetic opportunities including the attack of nucleophiles at C-4. Metal cyanides such as KCN represent synthetically valuable C-1 building blocks that could efficiently be coupled by palladium catalysis to alkenyl triflates [46–47] or alkenyl halides [48–49] forming α,β-unsaturated nitriles. As shown in Scheme 7, we adopted a protocol described by Yamamura and Murahashi [48] and found that the palladium-catalyzed coupling of anti - 4d with potassium cyanide in the presence of 18-crown-6 at 80 °C in toluene afforded the desired 5-cyano-substituted product anti - 25 in moderate yield (not optimized).…”

Section: Resultsmentioning

confidence: 99%

Iodination of carbohydrate-derived 1,2-oxazines to enantiopure 5-iodo-3,6-dihydro-2H-1,2-oxazines and subsequent palladium-catalyzed cross-coupling reactions

Medvecký

Linder

Schefzig

et al. 2016

Beilstein J. Org. Chem.

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Iodination of carbohydrate-derived 3,6-dihydro-2H-1,2-oxazines of type 3 using iodine and pyridine in DMF furnished 5-iodo-substituted 1,2-oxazine derivatives 4 with high efficacy. The alkenyl iodide moiety of 1,2-oxazine derivatives syn-4 and anti-4 was subsequently exploited for the introduction of new functionalities at the C-5 position by applying palladium-catalyzed carbon–carbon bond-forming reactions such as Sonogashira, Heck, or Suzuki coupling reactions as well as a cyanation reaction. These cross-coupling reactions led to a series of 5-alkynyl-, 5-alkenyl-, 5-aryl- and 5-cyano-substituted 1,2-oxazine derivatives being of considerable interest for further synthetic elaborations. This was exemplarily demonstrated by the hydrogenation of syn-21 and anti-24 and by a click reaction of a 5-alkynyl-substituted precursor.

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Section: Resultsmentioning

confidence: 99%

Iodination of carbohydrate-derived 1,2-oxazines to enantiopure 5-iodo-3,6-dihydro-2H-1,2-oxazines and subsequent palladium-catalyzed cross-coupling reactions

Medvecký

Linder

Schefzig

et al. 2016

Beilstein J. Org. Chem.

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“…[Liotta, 1974] A magnetically stirred mixture of 1,3-dichloropropane (5.08g, 45 mmol), dry KCN (11.7 g, 180 mmol), 18-crown-6 (1.01 g, 3.8 mmol) in acetonitrile (25 mL Displacement of vinyl halides becomes possible in the KCN/18-crown-6 system in the presence of (PhsPUPd [Yamamura, 1977].…”

Section: With Cyanide Ionmentioning

confidence: 99%

Phase Transfer Reactions

Ho¹

1998

Distinctive Techniques for Organic Synthesis

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Chemical reactions involving two or more molecules usually proceed at higher rates in one phase. However, it is not always feasible or expedient to render some reactions under homogeneous conditions. In such cases the phase transfer technique should be considered. Improvement of reactions by phase transfer catalysis (PTC) represents a breakthrough in chemical technology. Although sporadic reports appeared before the 1960s, consolidation of the concept through a series of publications on the theme of extractive alkylation [Markosza, 1965], a patent describing catalysis of heterogeneous reactions [Starks, 1968], and the observations concerning reactions of quaternary ammonium salts in nonpolar media [Brandstrom, 1969[Brandstrom, , 1972 initiated an avalanche of research in the methodology.While the most common phase transfer technique deals with reactants in two immiscible liquids, its scope encompasses gas-liquid, gas-solid, liquid-solid, and presumably solid-solid systems. In comparison with conventional methods, PTC holds considerable advantages in terms of cost (which avoids expensive anhydrous dipolar aprotic solvents), time, mildness, and simplicity. It is often observed that reactivities and selectivities are enhanced under such conditions.From an electrochemical study [Tan, 1994] of the Williamson ether synthesis under phase transfer catalysis, it is concluded that the role of the catalyst is to establish a Galvani distribution potential difference between the two phases which acts as the driving force for transferring the reactive ions from the aqueous medium to the organic layer.The general features of a typical PTC substitution reaction carried out in a system of organic and aqueous phases specifies reaction taking place in the organic layer. The phase transfer agent is present in catalytic amount and capable of moving one reactant in its resident solvent into that of the other reactant or the interfacial region. Only then the two species can react with reasonable speed. Needless to say that strong agitation is a most crucial to maximize reaction rates.Actually there are two mechanistic models for the PTC reaction. In the Starks extraction mechanism the catalyst is biphilic, thus well qualified by a quaternary ammonium or phosphonium salt, either of which having finite solubility in both phases on account of its charge and organophilicity, capable of ferrying the counter anion from the aqueous phase to the organic layer by the partition phenomenon. The 1 Distinctive Techniques for Organic Synthesis Downloaded from www.worldscientific.com by PURDUE UNIVERSITY on 04/13/15. For personal use only.2 Distinctive Techniques for Organic Synthesis anion generated from reaction will pair with the quaternary onium species and enter the aqueous phase and a second catalytic cycle starts at this point. The interfacial mechanism (proposed by Makosza and modified by Brandstrom and Montanari) describes cases in which the catalyst is highly organophilic and it functions by anion exchange in the interfacial region. In ot...

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“…A number of methods for the transformation of vinyl halides into a,P-unsaturated nitriles have been developed (7)(8)(9)(10), and citations therein). With respect to the present work, the reports by Yamamura and Murahashi (7) and Prochazka and Siroky (10) are particularly pertinent.…”

Section: R'o Cn + ~F I Rdmentioning

confidence: 99%