Silyl Derivatives of the Mixed Sandwiches Cyclopentadienyl Manganese Benzene and Cyclopentadienyl Manganese Biphenyl, CpMn(C6H6) and CpMn(C6H5-Ph)

Mixed manganese sandwich complexes containing a silyl-substituted cyclopentadienyl ring, e. g. (η5 - C5H4 - R)Mn(η6- C6H6) (3a - c) and (η5- C5H4 - R)Mn(η6- C6H5 - Ph) (4a - c); (R = SiMe3 (a), Si2Me5 (b) and SiMe2tBu (c)), were obtained in low yield via intermediates {(η5 - C5H4 - R)MnCl} and their reaction with phenyl Grignard reagents. Use of the 4-trimethylsilyl-phenyl magnesium halide in the reaction with the intermediate {CpMnCl} led to complexes with silylsubstituted arene rings, CpMn(η6 - C6H5 - R′) (5a) and CpMn(η6 -R′ - C6H5 - C6H5 - R′) (6a); (R′ = SiMe3 (a)). Dilithiation of CpMn6H6) (1) and subsequent reaction with a chlorosilane gave (η5-C5H4 - R)Mn(η6 - C6H5 - R′) (7a,b); (R = R′ = SiMe3 (a), Si2Me5 (b)). A cyclophane 8 in which five- and six-membered ring are linked through a -Me2Si-SiMe2- bridge was obtained using 1,2-dichloro-tetramethyldisilane. The mixed manganese sandw ich complexes were thoroughly characterized by 1H , 13C, 29Si and 55Mn NMR spectroscopy. The 55Mn spectra can be used to detect low-yield side-products.

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Zur Reaktion von Diboran mit Grignard-Verbindungen in Gegenwart von Äthern / Concerning the Reaction of Diborane with Grignard-Reagents in Ether Solutions

Zeitschrift für Naturforschung B ◽

10.1515/znb-1970-0803 ◽

1970 ◽

Vol 25 (8) ◽

pp. 780-786 ◽

Cited By ~ 9

Author(s):

J. Ewerling ◽

H. Nöth

Keyword(s):

Nmr Spectroscopy ◽

Pure State ◽

Grignard Reagents ◽

Magnesium Halide

The reaction between diborane and solutions of RMgX (R = CH3, C2H5, C6H5CH2; X = Cl, Br, J) in ether or tetrahydrofurane (THF) has been studied. The magnesium halide tetrahydridoborates are formed which can be readily isolated from THF solutions as the crystalline solvates MgX (BH4) · 2 THF. Species of the type RBH3⊖ and R2BH2⊖ but not R3BH⊖ can be detected by means of 11B nmr spectroscopy in solutions containing excess RMgX; they represent intermediates in the BH4⊖ producing steps. However, contrary to the literature, no hydridomagnesiumhalides, HMgX, could be isolated in a pure state and only for the case X = Cl was it possible to obtain mixtures of MgCl2 with MgH-containing species, both solvated. from THF solutions.

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Therapeutic Journey of 5-Pyrazolones as a Versatile Scaffold: A Review

Mini-Reviews in Medicinal Chemistry ◽

10.2174/1389557521999210101224058 ◽

2021 ◽

Vol 21 ◽

Author(s):

Ravinder Sharma ◽

Pooja A. Chawla ◽

Viney Chawla ◽

Rajeev Verma ◽

Nandita Nawal ◽

...

Keyword(s):

Severe Acute Respiratory Syndrome ◽

Protease Inhibitor ◽

Medicinal Chemistry ◽

Membered Ring ◽

Present Review ◽

Biological Profile ◽

3C Protease ◽

Structure Activity ◽

Derivatives Of ◽

Heterocyclic Moiety

Abstract: A sizeable proportion of currently marketed drugs come from heterocycles. The heterocyclic moiety 5-pyrazolone is well known five membered ring containing nitrogen. Derivatives of this wonder nucleus have exhibited activities as diverse as antimicrobial, anti-inflammatory, analgesic, antidepressant, anticonvulsant, antidiabetic, antihyperlipidemic, antiviral, antitubercular, antioxidant, anticancer and antiviral including action against severe acute respiratory syndrome (SARS) or 3C protease inhibitor. A number of drugs based on this motif have already made it to the market. Standard texts and literature on medicinal chemistry cite different approaches for the synthesis of 5-pyrazolones. The present review provides an insight view to 5-pyrazolone synthesis, their biological profile and structure activity relationship studies.

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Acyl derivatives of hydroxylamine. XV. Configuration of O-alkylhydroxamic acid determined by NMR spectroscopy

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19693325 ◽

1969 ◽

Vol 34 (11) ◽

pp. 3325-3335 ◽

Cited By ~ 6

Author(s):

D. Šnobl ◽

O. Exner

Keyword(s):

Nmr Spectroscopy ◽

Derivatives Of ◽

Acyl Derivatives

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The melanocyte stimulating activity of N-nitroso-2-chloroethyl-carbamoyl derivatives of α-melanotropin fragments

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19882574 ◽

1988 ◽

Vol 53 (11) ◽

pp. 2574-2582 ◽

Cited By ~ 5

Author(s):

Hedvig Medzihradszky-Schweiger ◽

Helga Süli-Vargha ◽

József Bódi ◽

Kálmán Medzihradszky

Keyword(s):

Biological Activity ◽

Active Site ◽

Frog Skin ◽

Terminal Sequence ◽

Subsequent Reaction ◽

Affinity Labels ◽

Derivatives Of

A number of N-nitroso-2-chloroethyl-carbamoyl (Q(NO)) derivatives of α-melanotropin fragments have been synthesized and their effect on the frog skin melanocytes studied. Peptides substituted in this way possess the biological activity of the parent compounds, indicating that they preserved their receptor recognizing ability. These compounds can therefore serve as affinity labels. Some of these derivatives, related to the C-terminal sequence of α-melanotropin show prolonged darkening reaction, which does not influence the subsequent reaction of melanocytes with α-melanotropin. The Q(NO)-derivative of a fragment derived from the classical active site of the hormone shows, however, inhibition of the effect of α-melanotropin. It can be concluded that the latter peptide acts through the melanotropin receptor, while others, related to the C-terminal sequence of the hormone through another mechanism.

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Monitoring the encapsulation of chlorin e6 derivatives into polymer carriers by NMR spectroscopy

Journal of Porphyrins and Phthalocyanines ◽

10.1142/s1088424619501815 ◽

2019 ◽

Vol 23 (11n12) ◽

pp. 1576-1586 ◽

Cited By ~ 1

Author(s):

Sara Pfister ◽

Luca Sauser ◽

Ilche Gjuroski ◽

Julien Furrer ◽

Martina Vermathen

Keyword(s):

Relaxation Time ◽

Nmr Spectroscopy ◽

Core Region ◽

Chlorin E6 ◽

Polypropylene Glycol ◽

Polymer Carriers ◽

H Nmr ◽

Line Shape Analysis ◽

Dynamic Methods ◽

Derivatives Of

The encapsulation of five derivatives of chlorin e6 with different hydrophobicity and aggregation properties into a series of five poloxamer-type triblock copolymer micelles (BCMs) with varying numbers of polyethylene and polypropylene glycol (PEG, PPG) units was monitored using 1H NMR spectroscopy. NMR chemical shift and line shape analysis, as well as dynamic methods including diffusion ordered spectroscopy (DOSY) and T1 and T2 relaxation time measurements of the chlorin and the polymer resonances, proved useful to assess the chlorin–BCM compatibility. The poloxamers had high capability to break up aggregates formed by chlorins up to intermediate hydrophobicity. Physically entrapped chlorins were always localized in the BCM core region. The loading capacity correlated with chlorin polarity for all poloxamers among which those with the lowest number of PPG units were most efficient. DOSY data revealed that relatively weakly aggregating chlorins partition between the aqueous bulk and micellar environment whereas more hydrophobic chlorins are well retained in the BCM core region, rendering these systems more stable. T1 and T2 relaxation time measurements indicated that motional freedom in the BCM core region contributes to encapsulation efficiency. The BCM corona dynamics were rather insensitive towards chlorin entrapment except for the poloxamers with short PEG chains. The presented data demonstrate that 1H NMR spectroscopy is a powerful complementary tool for probing the compatibility of porphyrinic compounds with polymeric carriers such as poloxamer BCMs, which is a prerequisite in the development of stable and highly efficient drug delivery systems suitable for medical applications like photodynamic therapy of tumors.

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