Synthesis of a bulky bis(imino)pyridine compound: a methodology for systematic variation of steric bulk and energetic implications for metalation
作者:Janelle E. Steves、Margaret D. Kennedy、Karen P. Chiang、William S. Kassel、William G. Dougherty、Timothy J. Dudley、Deanna L. Zubris
DOI:10.1039/b815987d
日期:——
A new bis(imino)pyridine compound, 2,6-(2,6-Me2-C6H3)NC(t-Bu)}2C5H3N (6), has been synthesized with t-butyl substituents on the imino carbon atoms. The stepwise synthetic method for assembly of this compound is novel. Compound 6 and its synthetic precursor, mono(imino)pyridine 3, have been characterized using single-crystal X-ray diffraction. Metalation attempts of 6 using iron(II) chloride under forcing conditions does not yield the desired iron(II) chloride complex; the use of refluxing acetic acid solvent provides a minimal amount of a paramagnetic species that has been characterized by NMR spectroscopy and magnetic susceptibility (NMR method). Computational methods have been used to evaluate the relative energies of three conformations of bis(imino)pyridine ligands with varying alkyl substitution at the imino carbon positions. The relative energies of these closed, open and open-planar conformations of 6 reveal a thermodynamic argument for the difficulty in metalation of 6, as compared to related ligands with less steric hindrance at the imino carbon atoms.
Triketiminate bis(borohydride) complexes of rare-earth metals [(2,6-Me2C6H3N=CMe)2C(2,6-Me2C6H3N=CBut)]Ln(BH4)2(THF)2 (Ln = Y, Nd): synthesis, structure, and catalytic activity in polymerization of rac-lactide, ε-caprolactone, and isoprene
作者:G. G. Skvortsov、A. V. Cherkasov、A. A. Trifonov
DOI:10.1007/s11172-017-1939-9
日期:2017.9
6-Me2C6H3N=CBut)]Ln(BH4)2(THF)2 (Ln = Y (3), Nd (4)). As opposed to the complexes with neutral triketimine, the monoanionic triketiminate ligand is coordinated to Li and Y or Nd cations in a bidentate fashion. Complexes 3 and 4 catalyze the polymerization of rac-lactide and ε-caprolactone; in combination with [Ph3C][B(C6F5)4] and AlBu3i (1 : 1 : 10 molar ratio), these compounds exhibit catalytic activity in the
通过亚胺酰氯2,6-Me2C6H3N=CClBut与二酮亚胺锂(2,6-Me2C6H3N= CMe)2CHLi。在结晶状态下,化合物 1 以二亚胺烯胺形式存在;在溶液中,以三亚胺形式。三酮亚胺 1 与正丁基锂在 0 °C 的 THF 中金属化生成三酮亚胺锂 [(2,6-Me2C6H3N=CMe)2C(2,6-Me2C6H3N=CBut)]Li(THF)2 (2)。Ln(BH4)3(THF)3 (Ln = Y, Nd) 与化合物 2(1:1 摩尔比,THF)的复分解反应得到中性三酮亚胺双(硼氢化物)配合物 [(2,6-Me2C6H3N=CMe )2C(2,6-Me2C6H3N=CBut)]Ln(BH4)2(THF)2 (Ln = Y (3), Nd (4))。与与中性三酮亚胺的配合物相反,单阴离子三酮亚胺配体以双齿方式与 Li 和 Y 或 Nd 阳离子配位。配合物3和4催化外消旋丙交酯和ε-己内酯的聚合;与
Sulphuric acid immobilized on silica gel (H<sub>2</sub>SO<sub>4</sub>–SiO<sub>2</sub>) as an eco-friendly catalyst for transamidation
作者:Sk. Rasheed、D. Nageswar Rao、A. Siva Reddy、Ravi Shankar、Parthasarathi Das
DOI:10.1039/c4ra16571c
日期:——
A novel method of transamidation of carboxamides with amines using catalytic amounts of H2SO4–SiO2 under solvent-free conditions has been developed. The scope of the methodology has been demonstrated with primary and secondary amines.
Organocatalytic Enantioselective Synthesis of Atropisomeric Aryl‐
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‐Quinones: Platform Molecules for Diversity‐Oriented Synthesis of Biaryldiols
作者:Ye‐Hui Chen、Heng‐Hui Li、Xiao Zhang、Shao‐Hua Xiang、Shaoyu Li、Bin Tan
DOI:10.1002/anie.202004671
日期:2020.7.6
Presented here is a class of novel axiallychiral aryl‐p ‐quinones as platform molecules for the preparation of non‐C2symmetric biaryldiols. Two sets of aryl‐p ‐quinone frameworks were synthesized with remarkable enantiocontrol by means of chiral phosphoric acid catalyzed enantioselective arylation of p ‐quinones by central‐to‐axialchirality conversion. These aryl‐p ‐quinones were then used to access
DFT-Guided Phosphoric-Acid-Catalyzed Atroposelective Arene Functionalization of Nitrosonaphthalene
作者:Wei-Yi Ding、Peiyuan Yu、Qian-Jin An、Katherine L. Bay、Shao-Hua Xiang、Shaoyu Li、Ying Chen、K.N. Houk、Bin Tan
DOI:10.1016/j.chempr.2020.06.001
日期:2020.8
naphthalene via chiral phosphoric acid catalysis. This strategy enables efficient construction of atropisomeric indole-naphthalenes and indole-anilines with excellent stereocontrol. Density functional theory (DFT) calculations provide further insights into the origins of enantioselectivity and the reaction mechanisms. The successful application in the synthesis of NOBINs (2-amino-2′-hydroxy-1,1′-binaphthyl)