Mechanism of arylation of nucleophiles by aryllead triacetates. Part 1. Exclusion of a pathway involving aryl free radicals

Morgan, J.; Pinhey, John T.

doi:10.1039/p19930001673

Cited by 20 publications

(29 citation statements)

References 16 publications

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“…Pd(bq)A C H T U N G T R E N N U N G (cod), Pd 2 (bq) 2 A C H T U N G T R E N N U N G (nbe) 2 , boronic acids 13 and 20 were prepared according to the reported methods. [13,32,33] Boronic acid esters are commercially available or readily obtained from the corresponding boronic acids through condensation with diols in refluxing THF using the Dean-Stark apparatus. All products except for 13e, j were known compounds previously reported in the literatures.…”

Section: Experimental Section Generalmentioning

confidence: 99%

The First General and Selective Palladium(II)‐Catalyzed Alkoxycarbonylation of Arylboronates: Interplay among Benzoquinone‐Ligated Palladium(0) Complex, Organoboron, and Alcohol Solvent

Yamamoto

2010

Adv Synth Catal

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Section: Experimental Section Generalmentioning

confidence: 99%

The First General and Selective Palladium(II)‐Catalyzed Alkoxycarbonylation of Arylboronates: Interplay among Benzoquinone‐Ligated Palladium(0) Complex, Organoboron, and Alcohol Solvent

Yamamoto

2010

Adv Synth Catal

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“…)], 34.87 )] and 31.49 (CMe,); m/z 372 (M', loo%), 357 (29), 342 (2), 326 (8), 301 (lo), 270 (lo), 269 (1 l), 241 (7), 168 (6), 69 (7), 57 (44) and 41 (17) [PTLC developer: dichloromethane-hexane (4: l)], m.p. 120-121.5 "C (from MeOH), v,,,(CHCl,)/cm~ ' 3534,2947, 2345, 1273, 1126, 756 and 609; A,,,(MeOH)/nm 207.5 (&/dm3 mol-' cm-' 29 136) and 276 (5702); 6,7.43-7.19 (2 H, m, 4'-and 6'-H), 7.15 (1 H,d,J1.87,6-H),7.08-6.95(2H,m,3'-and5'-H),6.89(1H,d, J1.83,4-H),4.40(1 H,s,OH), 3.75(3H,s,2'-OMe), 1.34(9H,s, 5-Bu') and 1.14 (9 H,s,6,, )], 34.81 )], 31.94 )] and 31.37 )]; m/z 313 (M+ + 1,25%), 312 (loo), 297 (62), 241 (61), 226 (21), 131 (1 l), 105 (12), 57 (87) and 40 (90) (Found: C, 3,phenoll9. [PTLC developer: dichloromethane-hexane (4 : l)], m.p.…”

Section: Methodsmentioning

confidence: 99%

ortho-Arylation of 3,5-di-tert-butylphenol with aryllead(IV) derivatives: a facile synthesis of sterically hindered phenols

Barton¹,

Donnelly²,

Guiry³

et al. 1994

J. Chem. Soc., Perkin Trans. 1

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Faculte des Sciences St Jerbme, 73397 Marseille Cedex 20, France The reaction of aryllead(iv) triacetates with 3,5-di-tert-butylphenol 1 has been shown to yield very hindered 2-aryl-3.5-di-tert-butylphenols and 2,6-diaryl-3,5-di-tert-butylphenols such as 15 and 16. The mechanism of this arylation reaction with aryllead(iv) derivatives is discussed. A free radical pathway has been excluded. The favoured pathway must involve the occurrence of covalent aryl(ary1oxy) lead(iv) diacetate intermediates, although they have not been detected. The required aryl cation behaviour of the lead reagents is supported b y 13C NMR spectroscopic studies on aryllead triacetates.

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“…For each sample about 64 scans were required to obtain a satisfactory signal-to-noise ratio. 13 C and 207 Pb CP/MAS NMR spectra were acquired, at 50.32 and 41.868 MHz respectively, on a Bruker MSL200 spectrometer, with a multinuclear, proton-enhanced, double bearing magic angle sample spinning probe, using a dry nitrogen gas supply. Inside an inert atmosphere box, approximately 250 mg of sample was packed into 7 mm zirconia rotors with Kel-F caps.…”

Section: Solution Nmr Spectroscopymentioning

confidence: 99%

“…42 Temperature measurement and regulation of the bearing gas were controlled with a Bruker B-TV1000 unit equipped with a copper-constantan thermocouple and digital reference. Temperature calibration was achieved both with the samarium ethanoate tetrahydrate Curie Law 13 71 Chemical Shift Anisotropy (CSA) calculations were performed on integrated intensities of the sidebands and analyzed with the Herzfeld-Berger method using the HBA routine of the WSolids computer program. 48 The CSA tensors are reported following the suggestions of Harris 72 with d 11 > d 22 > d 33 along with the span, X = d 11 − d 33 , and the skew,…”

Section: Solution Nmr Spectroscopymentioning

confidence: 99%

Structural investigations of a lead(iv) tetraacetate–pyridine complex

et al. 2005

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A 1 : 1 crystalline complex of lead(IV) tetraacetate and pyridine (LTA-py) has been prepared. The single-crystal X-ray structure, at 296 and 150 K, establishes the presence of a relatively short Pb-N bond (2.307 A) within an intriguing seven-coordinate lead inner sphere consisting of the pyridine ligand and two bidentate and two monodentate acetate ligands. The pyridine occupies a surprising amount of the available coordination space and has induced a dramatic change in coordination compared to the four chelating acetate ligands found in lead tetraacetate (LTA). Thermal measurements (TGA/DSC) indicate the de-coordination of pyridine and its loss from the solid between 360 and 380 K. (207)Pb CP/MAS NMR spectroscopy also demonstrates the existence of the Pb-N bond through observation of (1)J((207)Pb,(14)N)= 63 Hz and a (207)Pb-(14)N dipolar coupling constant, of 149 Hz. The solid-state (207)Pb NMR parameters are used to give insight into the coordination environment of Pb(iv) in LTA-py. In solution, ligand exchange is rapid on chemical shift and J-coupling time scales. A (207)Pb NMR study of the titration of an LTA solution by pyridine yields a stability constant for LTA-py of K = 1.5 M(-1) and predicts it to have a (207)Pb NMR chemical shift essentially identical to that observed by CP/MAS NMR in the solid state. This correlation between the solid state and solution indicates that the seven-coordinate LTA-py structure found in the crystalline state does persist in solution, and this could further explain why the addition of pyridine has such profound effects on lead(IV) carboxylate-mediated organic reactions. Simulations of exchange-broadened line shapes of (13)C CP/MAS NMR spectra in the temperature regime above 280 K indicate local motion of the pyridine rings in the form of 180 degrees jumps (activation energy 72.5 kJ mol(-1)); these are first such ring flips reported for a coordinated pyridine ligand.

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Mechanism of arylation of nucleophiles by aryllead triacetates. Part 1. Exclusion of a pathway involving aryl free radicals

Cited by 20 publications

References 16 publications

The First General and Selective Palladium(II)‐Catalyzed Alkoxycarbonylation of Arylboronates: Interplay among Benzoquinone‐Ligated Palladium(0) Complex, Organoboron, and Alcohol Solvent

The First General and Selective Palladium(II)‐Catalyzed Alkoxycarbonylation of Arylboronates: Interplay among Benzoquinone‐Ligated Palladium(0) Complex, Organoboron, and Alcohol Solvent

ortho-Arylation of 3,5-di-tert-butylphenol with aryllead(IV) derivatives: a facile synthesis of sterically hindered phenols

Structural investigations of a lead(iv) tetraacetate–pyridine complex

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