Cooperative Catalyst Effects in Palladium-Mediated Cyanation Reactions of Aryl Halides and Triflates

Anderson, Benjamin A.; Bell, Edward C.; Ginah, Francis O.; Harn, Nancy K.; Pagh, Lisa M.; Wepsiec, James P.

doi:10.1021/jo9808674

Cited by 150 publications

(45 citation statements)

References 31 publications

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“…Next, 4 was treated with a twofold excess of zinc cyanide in the presence of LiCl and a catalytic amount of [Pd(PPh 3 ) 4 ] in N,Ndimethylformamide (DMF) at 120°C. [23] The solvent was removed, and the residue was extracted into chloroform/methanol (98:2 v/v) to afford cyclotricyanotribenzylene 1 in pure form in 75 % yield. Cyclotricyanotrianisylene 2 has been reported All of the self-assembly experiments that were undertaken with CTBs 1 or 2 and [Pd(dppp)][OTf ] 2 or [Pt(dppp)][OTf ] 2 are summarized in Scheme 1, and the data for all of the cryptophanes in this study and their precursors are collected in Tables 1 ( 1 H NMR and IR spectroscopy) and 2 ( 13 C and 31 P NMR spectroscopy).…”

Section: Ligand Synthesismentioning

confidence: 99%

The Stereoselective Self‐Assembly of Chiral Metallo‐Organic Cryptophanes

et al. 2016

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International audienceCryptophanes are macropolycyclic cyclophanes constructed from two triply bridged concave cyclotriveratrylene analogues that encapsulate a large range of molecular and monoatomic substrates. Self-assembled metallo-organic cryptophanes based on M2+–carbonitrile (M = Pd or Pt) interactions have been obtained through the reactions of chiral nitrile-substituted cyclotribenzylenes (CTBs) 1 and 2 with [M(dppp)][OTf]2 (dppp = 1,3-bisdiphenylphosphinopropane, OTf = triflate) in 2:3 ratios in chlorinated solvents. The cryptophanes [Pd3(dppp)3(1)2]6+ and [Pd3(dppp)3(2)2]6+ were obtained exclusively in the chiral anti form in solution at room temperature whatever solvent was used; however the meso,syn form was identified as the major isomer of [Pd3(dppp)3(1)2]6+ at low temperature in CD2Cl2, and – in the case of [Pt3(dppp)3(1)2]6+ – it formed in a minor amount at room temperature. [Pd3(dppp)3(1)2][OTf]6 and [Pt3(dppp)3(1)2][OTf]6 crystallized in the anti forms with an encapsulated chloroform molecule, and gas-phase DFT calculations with the dispersion-corrected B97-D3 functional show that it is stabilized by 34.6 kJ mol–1. Interestingly, the heteroleptic cryptophane [Pd3(dppp)3(1)(2)]6+ was not detected in mixtures of [Pd(dppp)]2+ and CTBs 1 and 2 in a 3:1:1 ratio or through the equilibration of a 1:1 mixture of the preformed homoleptic cryptophanes; this points to favored self-sorting processes

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Section: Ligand Synthesismentioning

confidence: 99%

The Stereoselective Self‐Assembly of Chiral Metallo‐Organic Cryptophanes

et al. 2016

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“…The most economical route to the carboxy function would presumably be palladium-catalyzed halogen/cyano exchange [17,18] and subsequent hydrolysis of the resulting nitrile, or the palladium-or nickel-catalyzed carbonylation [19] of chloro or bromo derivatives of hetarenes. However, for operational simplicity, we preferred to make the acids by carboxylation of organolithium or organomagnesium intermediates, which could easily be generated by hydrogen/metal or halogen/metal permutation.…”

Section: Introductionmentioning

confidence: 99%

Recommendable Routes to Trifluoromethyl‐Substituted Pyridine‐ and Quinolinecarboxylic Acids

et al. 2003

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As part of a case study, rational strategies for the preparation of all ten 2-, 3-, or 4-pyridinecarboxylic acids and all nine 2-, 3-, 4-, or 8-quinolinecarboxylic acids bearing trifluoromethyl substituents at the 2-, 3-, or 4-position were elaborated. The trifluoromethyl group, if not already present in the precursor, was introduced either by the deoxygenative fluorination of suitable carboxylic acids with sulfur tetrafluoride or by the

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“…From the above facts, the optimum reaction conditions involve the use of 15 mol% CuI unlike that most often utilized combination of 10 mol% CuI to 5 mol% Pd-catalyst. 4,10 The additional bromopyrazines 1 9 afforded high yields of acylpyrazines 3 and 5 under the conditions verified here (Table 3).…”

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confidence: 75%

Studies on Pyrazines; 38: Acylation of Bromopyrazines and 2-Bromopyridine via Copper-Cocatalytic Stille Reaction

Sato¹,

Narita²

2004

Synthesis

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Synthesis of acetylpyrazines 3 and propionylpyrazines 5 was achieved by copper-cocatalytic Stille reaction of bromopyrazines 1 with tributyl(1-ethoxyalkenyl)tin and then acidic hydrolysis. The optimal reaction conditions involve the combination of 15 mol% CuI with 5 mol% of PdCl 2 (Ph 3 P) 2 . Similarly, 2-acylpyridines and propionylbenzenes were prepared from the corresponding aryl bromides.The Stille cross-coupling of bromobenzenes with trialkyl(1-ethoxyvinyl)tin followed by acidic hydrolysis has been shown as a convenient method for the synthesis of acetophenones. 2,3 In a preceding paper, we reported this methodology to be also effective in the dehalogenative acylation of electron-deficient nitrogen heteroaromatics, thus high yields of 1,3-dihydro-6-propionylpterin-2,4-diones were synthesized via Pd-catalyzed reaction of the 6-bromopteridines with tributyl(1-ethoxyprop-1-enyl)tin. 1 The key for the successful transformation was the use of CuI under the traditional Stille conditions, in other words the cross-coupling did not proceed at all without the additive. The cocatalytic effect of CuI in the Stille coupling was first reported by Liebeskind and Fengl, 4 and the many subsequent applications have stimulated a considerable development in this chemistry. 5 Much less is known, however, about the couplings of aryl halides with trialkyl(1-ethoxyalkenyl)tin in the presence of CuI. 6 On the other hand, acylpyrazines are of interest as the constituents in foodstuffs or pheromones, which have been often prepared by the Minisci-type radical reaction of pyrazines 7 or lithiation followed by reaction of the resultant lithiopyrazines with N,N-dialkylamides. 8 These methods suffer from some drawbacks, especially the regioselectivity of aromatic substitution. In this respect, acylation via displacement of halogeno substituent is a promising synthetic route to the desired acylpyrazines. We are currently investigating the acylation of bromopyrazines through copper-cocatalytic Stille reaction with 1-ethoxyvinyl or 1-ethoxypropenyl tin compounds (Scheme 1). Additionally, the cross-coupling of halogenopyridines and bromobenzenes was carried out under similar conditions for comparison of reactivity with pyrazine series.We first examined Pd-catalysts in the cross-coupling of 2-bromo-5-phenylpyrazine (1a) 9 with tributyl(1-ethoxyvinyl)tin (2), in which 5 mol% each of Pd catalyst and CuI were employed in refluxing MeCN containing triethylamine (Table 1, entries 1-3) according to our previous procedure. 1 Consequently, PdCl 2 (Ph 3 P) 2 induced the best yield (81%) of 2-acetyl-5-phenylpyrazine (3a). When toluene 2 was used as the solvent instead of MeCN, the yield of 3a decreased to 72%. The effects of Pd-catalyst, CuI and triethylamine can be realized from the experiments lacking each additive (entries 4-9). Without the Pdcatalyst, the coupling proceeded only slightly. The addition of CuI unexpectedly led to an appreciable increase in the yield of acetylpyrazine 3a. Our previous cross-coupling of bromopteridines necessitated cat...

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Cooperative Catalyst Effects in Palladium-Mediated Cyanation Reactions of Aryl Halides and Triflates

Cited by 150 publications

References 31 publications

The Stereoselective Self‐Assembly of Chiral Metallo‐Organic Cryptophanes

The Stereoselective Self‐Assembly of Chiral Metallo‐Organic Cryptophanes

Recommendable Routes to Trifluoromethyl‐Substituted Pyridine‐ and Quinolinecarboxylic Acids

Studies on Pyrazines; 38: Acylation of Bromopyrazines and 2-Bromopyridine via Copper-Cocatalytic Stille Reaction

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