Autoxidation of Heterocyclic Aminals

The autoxidation reactions of 2-acyl-2,3-dihydroquinazolin-4­(1<i>H</i>)-ones <b>4a</b> and <b>5a</b> and 2,2′-bis­(dihydroquinazolinone) <b>6a</b> are described. These reactions generate aminyl radicals that undergo β-C–C cleavage, and subsequent reactions of the resulting C-based radicals with O₂ lead to diverse products with good selectivity, depending on the structure of the substrate. Oxidation of <b>4a</b>, in which the 2-acyl group is part of a cyclic acenaphthenone unit, yields a heterocyclic <i>C</i>-hydroperoxylaminal via 1,2-acyl migration. Oxidation of <b>5a</b>, which contains a 2-acetyl group, yields peracetic acid and a quinazolinone product. Oxidation of <b>6a</b> forms a bis­(quinazolinone) by net dehydrogenation

(α-Diimine)nickel Complexes That Contain Menthyl Substituents: Synthesis, Conformational Behavior, and Olefin Polymerization Catalysis

We describe the synthesis and coordination chemistry of the (1<i>R</i>,2<i>S</i>,5<i>R</i>)-menthyl-substituted <i>N,N</i>′-diaryl-α-diimine ligands <i>N,N</i>′-(2-Men-4-Me-Ph)₂-BIAN (<b>L1</b>, Men = menthyl, BIAN = bis­(imino)­acenaphthene) and <i>N,N</i>′-(2-Men-4,6-Me₂-Ph)₂-BIAN (<b>L2</b>), the conformational properties of these ligands and their metal complexes, and the ethylene and 1-hexene polymerization behavior of the corresponding (α-diimine)­Ni complexes. Free ligands <b>L1</b> and <b>L2</b> and square-planar (<b>L1</b>)­PdCl₂ and (<b>L1</b>,<b>2</b>)­Ni­(acac)⁺ complexes exhibit a preference for the syn conformation, in which the two menthyl units are located on the same side of the NCCN plane, while tetrahedral (<b>L1</b>,<b>2</b>)­MX₂ (MX₂ = ZnCl₂, NiBr₂) complexes exhibit a preference for the <i>anti</i> conformation, in which the menthyl units are located on opposite sides of the NCCN plane. Both the <i>anti</i> and the <i>syn</i> conformers of [(<b>L2</b>)­Ni­(acac)]­[B­(C₆F₅)₄] can be activated by Et₂AlCl to generate highly active ethylene polymerization catalysts (activity (2.5–6.6) × 10⁶ g of PE/((mol of Ni) h) at 15 psi of C₂H₄, room temperature). The polyethylene produced by the <i>syn</i> conformer (<i>syn</i>/<i>anti</i> = 91/9) has a higher molecular weight (2×) and a higher branch density (3×) in comparison to that produced by the <i>anti</i> conformer. The polyhexene produced by the <i>syn</i> conformer (<i>syn</i>/<i>anti</i> = 91/9) contains a higher level of chain straightening (<i>syn</i> 50%, <i>anti</i> 41%) and a higher percentage of Me versus Bu branches (<i>syn</i> 24/26, <i>anti</i> 6/53) in comparison to that produced by the <i>anti</i> isomer. These results are indicative of a greater preference for 2,1-insertion and for chain walking (versus growth) following 1,2-insertion for the <i>syn</i> conformer

Hydrogen Bonding Behavior of Amide-Functionalized α‑Diimine Palladium Complexes

A class of (<i>N,N</i>′-diaryl-α-diimine)­Pd complexes bearing amide substituents on the N-aryl rings is described. Hydrogen bonding interactions involving the amide groups influence the structures, isomer distributions, and ligand coordination behavior of these compounds. The amide-functionalized α-diimine ligands (2,6-ⁱPr₂-Ph)­NCMeCMeN­(2-C­(O)­NMe₂-6-ⁱPr-Ph) (<b>4a</b>), (2,6-ⁱPr₂-Ph)­NCMeCMeN­(2,6-(C­(O)­NMe₂)₂-Ph) (<b>4b</b>), and (2-C­(O)­NMe₂-6-ⁱPr-Ph)­NCMeCMeN­(2-C­(O)­NMe₂-6-ⁱPr-Ph) (<b>4c</b>) were prepared by condensation reactions of 2,3-butanedione and the appropriate anilines. The attempted preparation of (2,6-ⁱPr₂-Ph)­NCMeCMeN­(2-C­(O)­NHMe-6-ⁱPr-Ph) (<b>4d</b>) yielded the corresponding 1,2-dihydroquinazolinone derivative <b>4d</b>′ formed by nucleophilic attack of the amide nitrogen at the proximal imine carbon. <b>4a</b> and <b>4b</b> react with (cod)­PdMeCl to yield square planar (α-diimine)­PdMeCl complexes <b>5a</b>,<b>a</b>′ and <b>5b</b>,<b>b</b>′, respectively, which exist as two isomers that differ in the orientation (trans/cis) of the Pd–Me ligand and the amide-substituted arylimine unit. <b>4c</b> reacts with (MeCN)₂PdCl₂ and (cod)­PdMeCl to yield (<b>4c</b>)­PdCl₂ (<b>6c-</b><i><b>anti</b></i>,<i><b>syn</b></i>) and (<b>4c</b>)­PdMeCl (<b>5c-</b><i><b>anti</b></i>,<i><b>syn</b></i>), which exhibit anti/syn isomerism due to hindered rotation of the C_aryl–N bonds. In the solid state, the amide oxygen atoms in <b>6c-</b><i><b>anti</b></i> and <b>5c-</b><i><b>syn</b></i> engage in hydrogen bonding with cocrystallized CH₂Cl₂ solvent molecules. <b>4d</b>′ reacts with (MeCN)₂PdCl₂ via ring-opening metalation to afford the α-diimine complex (<b>4d</b>)­PdCl₂ (<b>6d</b>). Transmetalation of <b>6d</b> with SnMe₄ yields (<b>4d</b>)­PdMeCl (<b>5d</b>,<b>d</b>′) as a mixture of trans and cis isomers. The reaction of <b>5d</b>,<b>d</b>′ with AgOAc yields (<b>4d</b>)­PdMe­(OAc) (<b>7d</b>) as a single isomer in which the Pd–Me group is trans to the amide-functionalized arylimine unit. <b>5d</b>, <b>6d</b>, and <b>7d</b> exhibit intramolecular N–H···Cl and N–H···O hydrogen bonding interactions involving the amide NH units. The reactions of <b>5a</b>,<b>a</b>′, <b>5c-</b><i><b>anti</b></i>, and <b>5d</b>,<b>d</b>′ with AgSbF₆ in the presence of pyrazole yield the corresponding (α-diimine)­PdMe­(pz)⁺SbF₆^– salts (<b>8a</b>,<b>c</b>,<b>d</b>; pz = pyrazole), which exhibit an intramolecular hydrogen bond between the amide oxygen and the pyrazole NH unit. <b>8a</b>,<b>c</b>,<b>d</b> undergo partial dissociation of pyrazole in CD₃CN solution to generate the corresponding CD₃CN complexes <b>9a</b>,<b>c</b>,<b>d</b>. The non-hydrogen-bonded complex {(2,6-ⁱPr₂-Ph)­NCMeCMeN­(2,6-ⁱPr₂-Ph)}­PdMe­(pz)⁺SbF₆^– (<b>8e</b>) and its pyrazole dissociation product {(2,6-ⁱPr₂-Ph)­NCMeCMeN­(2,6-ⁱPr₂-Ph)}­PdMe­(CD₃CN)⁺SbF₆^– (<b>9e</b>) were generated in a similar fashion. The pyrazole dissociation constants, <i>K</i>_eq = [(α-diimine)­PdMe­(CD₃CN)⁺] × [pz] × [(α-diimine)­PdMe­(pz)⁺]⁻¹, vary in the order <b>8e</b> > <b>8d</b> > <b>8a</b> > <b>8c</b>, span more than 2 orders of magnitude, and reflect the enhancement of pyrazole binding in <b>8a</b>,<b>c</b>,<b>d</b> by amide–pyrazole hydrogen bonding. The intramolecular hydrogen bonding in <b>8c</b> strengthens pyrazole binding by a factor of ca. 120 (i.e., ΔΔ<i>G</i> = 2.8(1) kcal mol^–1) relative to the case of <b>8e</b>

Hydrogen Bonding Behavior of Amide-Functionalized α‑Diimine Palladium Complexes

A class of (<i>N,N</i>′-diaryl-α-diimine)­Pd complexes bearing amide substituents on the N-aryl rings is described. Hydrogen bonding interactions involving the amide groups influence the structures, isomer distributions, and ligand coordination behavior of these compounds. The amide-functionalized α-diimine ligands (2,6-ⁱPr₂-Ph)­NCMeCMeN­(2-C­(O)­NMe₂-6-ⁱPr-Ph) (<b>4a</b>), (2,6-ⁱPr₂-Ph)­NCMeCMeN­(2,6-(C­(O)­NMe₂)₂-Ph) (<b>4b</b>), and (2-C­(O)­NMe₂-6-ⁱPr-Ph)­NCMeCMeN­(2-C­(O)­NMe₂-6-ⁱPr-Ph) (<b>4c</b>) were prepared by condensation reactions of 2,3-butanedione and the appropriate anilines. The attempted preparation of (2,6-ⁱPr₂-Ph)­NCMeCMeN­(2-C­(O)­NHMe-6-ⁱPr-Ph) (<b>4d</b>) yielded the corresponding 1,2-dihydroquinazolinone derivative <b>4d</b>′ formed by nucleophilic attack of the amide nitrogen at the proximal imine carbon. <b>4a</b> and <b>4b</b> react with (cod)­PdMeCl to yield square planar (α-diimine)­PdMeCl complexes <b>5a</b>,<b>a</b>′ and <b>5b</b>,<b>b</b>′, respectively, which exist as two isomers that differ in the orientation (trans/cis) of the Pd–Me ligand and the amide-substituted arylimine unit. <b>4c</b> reacts with (MeCN)₂PdCl₂ and (cod)­PdMeCl to yield (<b>4c</b>)­PdCl₂ (<b>6c-</b><i><b>anti</b></i>,<i><b>syn</b></i>) and (<b>4c</b>)­PdMeCl (<b>5c-</b><i><b>anti</b></i>,<i><b>syn</b></i>), which exhibit anti/syn isomerism due to hindered rotation of the C_aryl–N bonds. In the solid state, the amide oxygen atoms in <b>6c-</b><i><b>anti</b></i> and <b>5c-</b><i><b>syn</b></i> engage in hydrogen bonding with cocrystallized CH₂Cl₂ solvent molecules. <b>4d</b>′ reacts with (MeCN)₂PdCl₂ via ring-opening metalation to afford the α-diimine complex (<b>4d</b>)­PdCl₂ (<b>6d</b>). Transmetalation of <b>6d</b> with SnMe₄ yields (<b>4d</b>)­PdMeCl (<b>5d</b>,<b>d</b>′) as a mixture of trans and cis isomers. The reaction of <b>5d</b>,<b>d</b>′ with AgOAc yields (<b>4d</b>)­PdMe­(OAc) (<b>7d</b>) as a single isomer in which the Pd–Me group is trans to the amide-functionalized arylimine unit. <b>5d</b>, <b>6d</b>, and <b>7d</b> exhibit intramolecular N–H···Cl and N–H···O hydrogen bonding interactions involving the amide NH units. The reactions of <b>5a</b>,<b>a</b>′, <b>5c-</b><i><b>anti</b></i>, and <b>5d</b>,<b>d</b>′ with AgSbF₆ in the presence of pyrazole yield the corresponding (α-diimine)­PdMe­(pz)⁺SbF₆^– salts (<b>8a</b>,<b>c</b>,<b>d</b>; pz = pyrazole), which exhibit an intramolecular hydrogen bond between the amide oxygen and the pyrazole NH unit. <b>8a</b>,<b>c</b>,<b>d</b> undergo partial dissociation of pyrazole in CD₃CN solution to generate the corresponding CD₃CN complexes <b>9a</b>,<b>c</b>,<b>d</b>. The non-hydrogen-bonded complex {(2,6-ⁱPr₂-Ph)­NCMeCMeN­(2,6-ⁱPr₂-Ph)}­PdMe­(pz)⁺SbF₆^– (<b>8e</b>) and its pyrazole dissociation product {(2,6-ⁱPr₂-Ph)­NCMeCMeN­(2,6-ⁱPr₂-Ph)}­PdMe­(CD₃CN)⁺SbF₆^– (<b>9e</b>) were generated in a similar fashion. The pyrazole dissociation constants, <i>K</i>_eq = [(α-diimine)­PdMe­(CD₃CN)⁺] × [pz] × [(α-diimine)­PdMe­(pz)⁺]⁻¹, vary in the order <b>8e</b> > <b>8d</b> > <b>8a</b> > <b>8c</b>, span more than 2 orders of magnitude, and reflect the enhancement of pyrazole binding in <b>8a</b>,<b>c</b>,<b>d</b> by amide–pyrazole hydrogen bonding. The intramolecular hydrogen bonding in <b>8c</b> strengthens pyrazole binding by a factor of ca. 120 (i.e., ΔΔ<i>G</i> = 2.8(1) kcal mol^–1) relative to the case of <b>8e</b>

Copolymerization of Ethylene with Acrylate Monomers by Amide-Functionalized α‑Diimine Pd Catalysts

We report the ethylene homopolymerization and ethylene/methyl-acrylate (MA) and ethylene/acrylic-acid (AA) copolymerization behavior of a series of (<i>N,N</i>′-diaryl-α-diimine)­Pd catalysts that contain secondary amide (−CONHMe) or tertiary amide (−CONMe₂) substituents on the N-aryl rings, including the “first-generation” catalysts {(2,6-^<i>i</i>Pr₂-Ph)­NCMeCMeN­(2-CONHMe-6-^<i>i</i>Pr-Ph)}­PdMeCl (<b>1a</b>,<b>a</b>′) and {(2,6-^<i>i</i>Pr₂-Ph)­NCMeCMeN­(2-CONMe₂-6-^<i>i</i>Pr-Ph)}­PdMeCl (<b>1b</b>,<b>b</b>′) and the “second-generation” catalysts [{2,6-(CHPh₂)₂-4-Me-Ph}­NCMeCMeN­(2-CONHMe-6-^<i>i</i>Pr-Ph)]­PdMeCl (<b>1d</b>,<b>d</b>′) and [{2,6-(CHPh₂)₂-4-Me-Ph}­NCMeCMeN­(2-CONMe₂-6-^<i>i</i>Pr-Ph)]­PdMeCl (<b>1e</b>,<b>e</b>′). Activation of <b>1d</b>,<b>d</b>′ and <b>1e</b>,<b>e</b>′ by NaB­{3,5-(CF₃)₂C₆H₃}₄ generates active ethylene polymerization catalysts that produce highly branched (77–81 br/1000 C) polyethylenes with number-average molecular weights (<i>M</i>_ns) in the range 26–60 kDa. The replacement of two isopropyl units in <b>1a</b>,<b>a</b>′ and <b>1b</b>,<b>b</b>′ with benzhydryl groups in <b>1d</b>,<b>d</b>′ and <b>1e</b>,<b>e</b>′ leads to a significant improvement in ethylene homopolymerization performance. The secondary amide-functionalized catalyst <b>1d</b>,<b>d</b>′ incorporates ca. twice as much MA and ca. three times as much AA as the ^<i>i</i>Pr-substituted catalyst [{2,6-(CHPh₂)₂-4-Me-Ph}­NCMeCMeN­(2,6-^<i>i</i>Pr₂-Ph)]­PdMeCl (<b>1f</b>,<b>f</b>′) in copolymerization with ethylene. The reactions of <b>1a</b>,<b>a</b>′ and <b>1b</b>,<b>b</b>′ with metal salts that contain weakly coordinating anions lead to extrusion of CH₄ and the formation of [{(μ-κ²-<i>N,N</i>′,κ-<i>O</i>-α-diimine)­Pd}₂(μ-CH₂)]²⁺ complexes, in which the amide carbonyl O atoms coordinate to Pd centers

sj-xlsx-2-taj-10.1177_20406223241236258 – Supplemental material for Predictors of seizure outcomes in stereo-electroencephalography-guided radio-frequency thermocoagulation for MRI-negative epilepsy

Supplemental material, sj-xlsx-2-taj-10.1177_20406223241236258 for Predictors of seizure outcomes in stereo-electroencephalography-guided radio-frequency thermocoagulation for MRI-negative epilepsy by Qi Huang, Pandeng Xie, Jian Zhou, Haoran Ding, Zhao Liu, Tianfu Li, Yuguang Guan, Mengyang Wang, Jing Wang, Pengfei Teng, Mingwang Zhu, Kaiqiang Ma, Han Wu, Guoming Luan and Feng Zhai in Therapeutic Advances in Chronic Disease</p

sj-docx-1-taj-10.1177_20406223241236258 – Supplemental material for Predictors of seizure outcomes in stereo-electroencephalography-guided radio-frequency thermocoagulation for MRI-negative epilepsy

Supplemental material, sj-docx-1-taj-10.1177_20406223241236258 for Predictors of seizure outcomes in stereo-electroencephalography-guided radio-frequency thermocoagulation for MRI-negative epilepsy by Qi Huang, Pandeng Xie, Jian Zhou, Haoran Ding, Zhao Liu, Tianfu Li, Yuguang Guan, Mengyang Wang, Jing Wang, Pengfei Teng, Mingwang Zhu, Kaiqiang Ma, Han Wu, Guoming Luan and Feng Zhai in Therapeutic Advances in Chronic Disease</p