The Generation of Aryl Anions by Double Electron Transfer to Aryl Iodides from a Neutral Ground‐State Organic Super‐Electron Donor

Murphy, John A.; Zhou, Sen; Thomson, Douglas W.; Schoenebeck, Franziska; Mahesh, Mohan; Park, Stuart R.; Tuttle, Tell; Berlouis, L.E.A.

doi:10.1002/anie.200700554

Cited by 129 publications

(111 citation statements)

References 42 publications

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“…DMF or NH 3 (l)] containing strong base. [1,2] In all previous work from our laboratory, no evidence for carbene dimerization (Scheme 5) was observed during the H/D-exchange reactions in aqueous solution of all conjugate acids of NHCs studied to date including singly linked bisimidazolium ions 17 and 18. We hypothesized that the more rigid structure in bis-linked bis-imidazolium 4, and enforced close proximity of the imidazolium C(2)-H positions, could make dimerization more competitive with deuterium exchange.…”

Section: Implications For Dimerizationmentioning

confidence: 79%

Proton transfer reactions of a bridged bis‐propyl bis‐imidazolium salt

Massey

Quinn

Zhou

et al. 2016

J of Physical Organic Chem

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Tetraazafulvalene 1 has found broad application in reduction and other related transformations and is conveniently generated from bis‐propyl bis‐imidazolium salt 4 with a strong base in a non‐protic solvent. The proposed mechanism for the formation of 1 involves initial deprotonation at C(2) to give a mono‐carbene 9 followed by intramolecular reaction at the second azolium centre. Herein, we report the second‐order rate constants for deuteroxide‐catalysed exchange in aqueous solution of the C(2)‐hydrogens of bis‐propyl bis‐imidazolium di‐iodide salt 4 and related monomeric dipropyl imidazolium iodide 10 of kDO = 1.37 × 104 and 1.79 × 102 M−1 s−1, respectively, and used these data to calculate pKa values of 21.2 and 23.1. The greater C(2)‐H acidity of the doubly bridged bis‐propyl bis‐imidazolium salt 4 relative to 10 may be attributed to the inductive or electrostatic destabilization of the conjugate acid dicationic azolium ion 4 relative to the monocationic carbene 9, which is enhanced by bis‐tethering. Formation of tetraazafulvalene 1 was not observed under the aqueous conditions employed highlighting that carbene reprotonation significantly outcompetes dimerization under these conditions. Copyright © 2016 John Wiley & Sons, Ltd.

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Section: Implications For Dimerizationmentioning

confidence: 79%

Proton transfer reactions of a bridged bis‐propyl bis‐imidazolium salt

Massey

Quinn

Zhou

et al. 2016

J of Physical Organic Chem

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“…[2] EROs have therefore been labelled as organic super-electron donors. [3] In this context, the first ionisation potential of C 2 (NMe 2 ) 4 or [C{N(Me)CH 2 } 2 ] 2 is around 6 eV (cf. C 2 H 4 : 10.5 eV).…”

Section: Introductionmentioning

confidence: 99%

Reactivity of a Super‐Electron‐Rich Olefin Derived from Cyclam

et al. 2009

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A series of new compounds has been synthesised from an electron‐rich olefin derived from cyclam (A). Thus, A reacts with oxygen gas to give the syn‐bis(urea) 1 and with sulfur to yield the anti‐bis(thiourea) 2. The reaction of A with triflic acid furnishes the bis(imidazolium) triflate 3, which gives the monoprotonated imidazolium salt 4 upon treatment with sodium tetraphenylborate in water. Theoretical calculations (DFT) predict the diprotonated species to be energetically disfavoured, thus demonstrating the importance of hydrogen‐bonding interactions. Treatment of compound 3 with silver oxide affords the di‐ and monoprotonated cationic salts 5a and 5b in THF and dichloromethane, respectively. The molecular structures of compounds 1, 2, 3, 4, 5a and 5b have been established by X‐ray diffraction. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

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“…[1][2][3][4] In principle, the neutrality of these organic compounds should lead to high solubility and should open up the possibility of homogeneous reduction reactions in conventional media at low temperatures, unique selectivity, and new synthetic methodologies. Early work in this area involved reagents such as tetrathiafulvalene (TTF, 1) 5 and tetrakisdimethylaminoethylene (TDAE, 2), 6 10 Despite this, the significant time and synthetic challenges associated with the preparation of 3 are seen as limiting its utility as a commonplace reducing agent. 2 Electron donors based on alternate scaffolds, that are easier to prepare and offer similar, or even slightly increased, reducing power became available when Murphy described an elegant synthesis for amino-substituted bispyridinylidenes such as 4a (E 1/2 (DMF) = -1.24 V vs SCE).…”

Section: Introductionmentioning

confidence: 99%

Facile preparation and isolation of neutral organic electron donors based on 4-dimethylaminopyridine

Martin

Dyker

2018

Can. J. Chem.

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A number of new neutral bis-2-(4-dimethylamino)pyridinylidene electron donors featuring N-akyl groups of varying lengths (propyl, butyl, hexyl, dodecyl) have been prepared from 4-dimethylaminopyridine by means of a simple two-step procedure. Each derivative could be isolated in high yield and could be stored indefinitely under inert atmosphere. The electron donors were chemically oxidized to the corresponding bipyridinium ions, and all compounds were characterized by NMR spectroscopy and cyclic voltammetry. As an emerging class of electron transfer agents, the availability of the isolated neutral bispyridinylidenes should be beneficial for cases that are incompatible with generating the electron donor in situ.

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The Generation of Aryl Anions by Double Electron Transfer to Aryl Iodides from a Neutral Ground‐State Organic Super‐Electron Donor

Cited by 129 publications

References 42 publications

Proton transfer reactions of a bridged bis‐propyl bis‐imidazolium salt

Proton transfer reactions of a bridged bis‐propyl bis‐imidazolium salt

Reactivity of a Super‐Electron‐Rich Olefin Derived from Cyclam

Facile preparation and isolation of neutral organic electron donors based on 4-dimethylaminopyridine

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