Pyrazole Complexes and Supramolecular Chemistry

Pérez, Julio; Riera, Lucı́a

doi:10.1002/ejic.200900694

Cited by 111 publications

(42 citation statements)

References 81 publications

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“…The adjacent (1,2-positions) nitrogen atoms can play a role in the amphiprotic behaviour with a pyrrole-like σ-donor as well as a pyridine-like π-acceptor characters (31,32). The shape-dependent assembled cyclic structures (i.e.…”

Section: Introductionmentioning

confidence: 99%

Supramolecular dimeric structures of pyrazole-containing meso-oxo carbaphlorin analogues

Ishida

Fujimoto

Morimoto

et al. 2016

Supramolecular Chemistry

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Synthesis and properties of a novel meso-oxo carbaphlorin analogue embedded with an N-free pyrazole moiety are described. The N-benzyl precursor was prepared by a [3 + 1]-MacDonald condensation of N-benzyl pyrazole dialdehyde and β-alkyl-substituted tripyrrane dicarboxylic acid and subsequent oxidation by ferric chloride. Upon deprotection of the benzyl group, the resulting N-free oxophlorin analogue formed a unique supramolecular dimer through mutual hydrogen bonding interactions between the pyrazole NH and meso-carbonyl group. The assembled behaviour was characterised by various spectroscopies, X-ray crystallographic analysis and vapour pressure osmometry. Under the similar reaction conditions, the condensation of meso-phenyl-substituted tripyrrane derivative afforded an unprecedented tetrapyrrolic macrocycle fused with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone unit at their α-pyrrolic positions. The X-ray crystallographic analysis of the macrocycle revealed a twisted core structure, and nonaromatic nature was elucidated.

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Section: Introductionmentioning

confidence: 99%

Supramolecular dimeric structures of pyrazole-containing meso-oxo carbaphlorin analogues

Ishida

Fujimoto

Morimoto

et al. 2016

Supramolecular Chemistry

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“…Recently, we reported iridiumcoordinated pyrazole complexes as asymmetric H-bonding catalysts 36,37 . We hypothesized that the corresponding deprotonated pyrazolato complexes might serve as chiral Brønsted bases with an amino group in the 3-position of the coordinated pyrazolato ligand [42][43][44] (A in Fig. 1a) raising the basicity and serving as part of a double hydrogen acceptor site on protonation to the 3-aminopyrazole complex (B in Fig.…”

Section: Resultsmentioning

confidence: 99%

Metal-templated chiral Brønsted base organocatalysis

Ding

et al. 2014

Nat Commun

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Inert octahedral chiral-at-metal complexes are an emerging class of asymmetric catalysts that exploit the globular, rigid nature and stereochemical options of octahedral compounds. While the central transition metal serves as a structural anchorpoint and provides metal centrochirality, catalysis is mediated through the organic ligand sphere, thereby merging the branches of transition metal catalysis and organocatalysis. Here we report the development of inert octahedral 3-aminopyrazolato iridium(III) complexes as novel chiral Brønsted base catalysts and demonstrate their merit with applications to highly effective asymmetric sulfaMichael and aza-Henry reactions, permitting catalyst loadings down to 0.02 and 0.25 mol%, respectively. The observed high stereocontrol can be rationalized by a bifunctional mode of action in which the iridium catalyst, after the initial proton transfer, controls a ternary complex through defined hydrogen bonding interactions. This work reveals the potential of octahedral metal complexes as chiral scaffolds for the design of high-performance asymmetric catalysts.

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“…The importance of pyrazole derivatives has also been accompanied by an increasing interest focused on the coordination chemistry of these heterocycles [9][10][11]. Particularly, metal-based compounds of pyrazoles containing phosphines as co-ligands have also received attention due to their possible use as antitumor and antimicrobial drugs [12,13].…”

Section: Introductionmentioning

confidence: 99%

Pyrazolyl Pd(II) complexes containing triphenylphosphine: Synthesis and antimycobacterial activity

et al. 2015

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Pd(II) complexes containing triphenylphosphine: Synthesis and antimycobacterial activity, Polyhedron (2015), doi: http://dx.Abstract Complexes of the type trans-[PdCl 2 (HL)(PPh 3 )], where HL = pyrazole (1); 3,5-dimethylpyrazole (2); 4-nitropyrazole (3); 4-iodopyrazole (4) and PPh 3 = triphenylphosphine, were synthesized and characterized by elemental analyses, infrared and 1 H-NMR spectroscopies. Single-crystal X-ray diffraction determination on 3·0.9 CHCl 3 and 4 showed that the coordination geometry around Pd(II) is nearly square-planar, with the chloro ligands in a trans configuration. In vitro antimycobacterial evaluation demonstrated that compound 4 displayed a Minimum Inhibitory Concentration (MIC) of 7.61 ± 2.18 µM, being superior to the values observed for some commonly used antituberculosis drugs and other metal-based complexes.

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Pyrazole Complexes and Supramolecular Chemistry

Cited by 111 publications

References 81 publications

Supramolecular dimeric structures of pyrazole-containing meso-oxo carbaphlorin analogues

Supramolecular dimeric structures of pyrazole-containing meso-oxo carbaphlorin analogues

Metal-templated chiral Brønsted base organocatalysis

Pyrazolyl Pd(II) complexes containing triphenylphosphine: Synthesis and antimycobacterial activity

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