Diyne Cyclization in Camphor Derivatives - Experimental and Theoretical Investigation

1996 ◽  
Vol 51 (11) ◽  
pp. 1655-1662 ◽  
Author(s):  
Gabriele Wagner ◽  
Christian Heiß ◽  
Uwe Verfiirth ◽  
Rudolf Herrmann
Keyword(s):  
Oxygen Atom ◽  
Theoretical Investigation ◽  
Positive Charge ◽  
Membered Ring ◽  
Titanium Chloride ◽  
Nmr Studies ◽  
Methylene Carbon ◽  
Camphor Derivatives ◽  
Exocyclic Methylene ◽  
Derivatives Of

Derivatives of 3-oxo-camphorsulfonimide (1) with two phenylethynyl groups in the endo positions at the carbons C-2 and C-3 were prepared, and their reactivity towards halogenes and titanium chloride was studied. In every case, the two ethynyl groups led to the annulation of a five-membered ring to the bicyclo[2 .2 .1] system in an orientation which depends on the bulkiness of the additional substituent in position 3. NMR studies show that cationic species like 6 and 8 are the first detectable intermediates. They not only contain the fused five-membered ring but also a bond between its exocyclic methylene carbon and an oxygen atom of the sulfonyl group, thus transferring the positive charge mainly to sulfur. Semiempirical calculations (PM3) suggest two intermediates in the formation of such cations.

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

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.

1,3-dipolar cycloaddition in the synthesis of glycoconjugates of natural chlorins and bacteriochlorins

2009 ◽  
Vol 13 (03) ◽  
pp. 336-345 ◽  
Author(s):  
Mikhail A. Grin ◽  
Ivan S. Lonin ◽  
Anna A. Lakhina ◽  
Elena S. Ol'shanskaya ◽  
Alexey I. Makarov ◽  
...  
Keyword(s):  
Triple Bond ◽  
Tautomeric Form ◽  
Click Reaction ◽  
Copper Cation ◽  
Water Soluble ◽  
Dipolar Cycloaddition ◽  
Nmr Studies ◽  
Metal Free ◽  
Cu Complex ◽  
Derivatives Of

Glucose-, galactose- and lactose-containing photosensitizers based on derivatives of chlorophyll a and bacteriochlorophyll a were synthesized with the use of [3+2] cycloaddition between sugar azides and triple bond derivatives of chlorins and bacteriochlorins. Unlike bacteriochlorin cycloimide, chlorin was detected to form a Cu -complex during the click reaction. An approach to the synthesis of metal-free glycosylated chlorins was developed with the use of "protection" by Zn 2+ cation and subsequent demetalation. It is based on the action of alkynyl chlorin e6 derivative Zn -complex, which is resistant to the substitution by copper cation. Bacteriochlorin p cycloimide conjugate with per-acetylated β-D-lactose was obtained and shown to become water-soluble after unblocking of the lactose hydroxy functions. NMR studies allowed for the elucidation of structure, tautomeric form and conformation of the obtained compounds.

Metal-Betaine Interactions.XIV. Silver(I) 3-Carboxylato-1-pyridinioacetate Monohydrate, [Ag{C5H4(COO)NCH2.COO}]n.nH2O

1991 ◽  
Vol 44 (12) ◽  
pp. 1783 ◽  
Author(s):  
XM Chen ◽  
TCW Mak
Keyword(s):  
Oxygen Atom ◽  
Water Molecule ◽  
Lattice Water Molecule ◽  
Membered Ring ◽  
Zigzag Chain ◽  
Two Dimensional ◽  
Metal Centre ◽  
Lattice Water ◽  
Dimensional Network ◽  
Tetrahedral Environment

The complex silver(I) 3-carboxylato-1-pyridinioacetate monohydrate, [Ag{C5H4(COO)NCH2.COO}]n.nH2O, crystallizes in space group P21/c (No. 14), with Z-4, a 12.233(6), b 5.049(1), c 14.418(7)Ǻ, and β 94.96(4)°; the structure was refined to RF -0.057 for 1721 observed [I ≥ 3σ(I)] Mo Kα data. The silver(I) atom is coordinated by four carboxylato oxygen atoms in a distorted tetrahedral environment [Ag-O 2.284(5)-2.570(5)Ǻ]. The tridentate acetato group bridges the Ag1 atoms into a zigzag chain featuring an uncommon [Ag2( carboxylato -O,O′)(carboxylato-μ-1,1-O)] six- membered ring, and the coordination sphere about each metal centre is completed by the unidentate aromatic carboxylato group, resulting in a two-dimensional network in the solid. The lattice water molecule forms hydrogen bonds with the uncoordinated oxygen atom of the aromatic carboxylato group [2.755(9)Ǻ] and the coordinated oxygen atom of the acetato group [2.936(9)Ǻ].

scholarly journals Silylated gallium and indium chalcogenide ring systems as potential precursors to ME (E=O, S) materials

2013 ◽  
Vol 11 (7) ◽  
pp. 1225-1238
Author(s):  
Iliana Medina-Ramírez ◽  
Cynthia Floyd ◽  
Joel Mague ◽  
Mark Fink
Keyword(s):  
Thermal Decomposition ◽  
Room Temperature ◽  
Membered Ring ◽  
Molecular Structures ◽  
Nmr Studies ◽  
X Ray ◽  
X Ray Crystallography ◽  
High Yields ◽  
Vt Nmr ◽  
State 1

AbstractThe reaction of R3M (M=Ga, In) with HESiR′3 (E=O, S; R′3=Ph3, iPr3, Et3, tBuMe2) leads to the formation of (Me2GaOSiPh3)2(1); (Me2GaOSitBuMe2)2(2); (Me2GaOSiEt3)2(3); (Me2InOSiPh3)2(4); (Me2InOSitBuMe2)2(5); (Me2InOSiEt3)2(6); (Me2GaSSiPh3)2(7); (Et2GaSSiPh3)2(8); (Me2GaSSiiPr3)2(9); (Et2GaSSiiPr3)2(10); (Me2InSSiPh3)3(11); (Me2InSSiiPr3)n(12), in high yields at room temperature. The compounds have been characterized by multinuclear NMR and in most cases by X-ray crystallography. The molecular structures of (1), (4), (7) and (8) have been determined. Compounds (3), (6) and (10) are liquids at room temperature. In the solid state, (1), (4), (7) and (9) are dimers with central core of the dimer being composed of a M2E2 four-membered ring. VT-NMR studies of (7) show facile redistribution between four- and six-membered rings in solution. The thermal decomposition of (1)–(12) was examined by TGA and range from 200 to 350°C. Bulk pyrolysis of (1) and (2) led to the formation of Ga2O3; (4) and (5) In metal; (7)–(10) GaS and (11)–(12) InS powders, respectively.

The syntheses of 6-C-alkyl derivatives of methyl α-isomaltoside for a study of the mechanism of hydrolysis by amyloglucosidase

2001 ◽  
Vol 79 (2) ◽  
pp. 238-255 ◽  
Author(s):  
Ulrike Spohr ◽  
Nghia Le ◽  
Chang-Chun Ling ◽  
Raymond U Lemieux
Keyword(s):  
Hydrogen Bonds ◽  
Molecular Model ◽  
Aromatic Amino Acids ◽  
Hydroxyl Group ◽  
Bulk Solution ◽  
Anomeric Effect ◽  
Nmr Studies ◽  
Intermolecular Hydrogen Bonds ◽  
Model Calculations ◽  
Derivatives Of

The epimeric (6aR)- and (6aS)-C-alkyl (methyl, ethyl and isopropyl) derivatives of methyl α-isomaltoside (1) were synthesized in order to examine the effects of introducing alkyl groups of increasing bulk on the rate of catalysis for the hydrolysis of the interunit α-glycosidic bond by the enzyme amyloglucosidase, EC 3.2.1.3, commonly termed glucoamylase (AMG). It was previously established that methyl (6aR)-C-methyl α-isomaltoside is hydrolysed about 2 times faster than methyl α-isomaltoside and about 8 times faster than its S-isomer. The kinetics for the hydrolyses of the ethyl and isopropyl analogs were also recently published. As was expected from molecular model calculations, all the R-epimers are good substrates. A rationale is presented for the catalysis based on conventional mechanistic theories that includes the assistance for the decomposition of the activated complex to products by the presence of a hydrogen bond, which connects the 4a-hydroxyl group to the tryptophane and arginine units. It is proposed that activation of the initially formed complex to the transition state is assisted by the energy released as a result of both of the displacement of perturbed water molecules of hydration at the surfaces of both the polyamphiphilic substrate and the combining site and the establishment of intermolecular hydrogen bonds, i.e., micro-thermodynamics. The dissipation of the heat to the bulk solution is impeded by a shell of aromatic amino acids that surround the combining site. Such shields are known to be located around the combining sites of lectins and carbohydrate specific antibodies and are considered necessary to prevent the disruption of the intermolecular hydrogen bonds, which are of key importance for the stability of the complex. These features together with the exquisite stereoelectronic dispositions of the reacting molecules within the combining site offer a rationalization for the catalysis at ambient temperatures and near neutral pH. The syntheses involved the addition of alkyl Grignard reagents to methyl 6-aldehydo-α-D-glucopyranoside. The addition favoured formation of the S-epimers by over 90%. Useful amounts of the active R-isomers were obtained by epimerization of the chiral centers using conventional methods. Glycosylation of the resulting alcohols under conditions for bromide-ion catalysis, provided methyl (6aS)- and (6aR)-C-alkyl-hepta-O-benzyl-α-isomaltosides. Catalytic hydrogenolysis of the benzyl groups afforded the desired disaccharides. 1H NMR studies established the absolute configurations and provided evidence for conformational preferences.Key words: amyloglucosidase (AMG), exo-anomeric effect, 6-C-alkyl-α-D-glucopyranosides and isomaltosides, mechanism of enzyme catalysis.

scholarly journals Synthesis and NMR Studies of Z- and E-Isomers of 10-Oxo and 10-Hydroxy Derivatives of Amitriptyline and Nortriptyline.

1983 ◽  
Vol 37b ◽  
pp. 335-340 ◽  
Author(s):  
Niels Lassen ◽  
Jens Perregaard ◽  
Toshiaki Nishida ◽  
Curt R. Enzell ◽  
Jan-Eric Berg ◽  
...  
Keyword(s):  
Nmr Studies ◽  
Derivatives Of

The binding of analogues of coralyne and related heterocyclics to DNA triplexes

1995 ◽  
Vol 73 (1-2) ◽  
pp. 11-18 ◽  
Author(s):  
Laura J. P. Latimer ◽  
Natasha Payton ◽  
Gavin Forsyth ◽  
Jeremy S. Lee
Keyword(s):  
Thermal Denaturation ◽  
Positive Charge ◽  
Triplex Dna ◽  
Alkyl Chains ◽  
Dna Triplexes ◽  
Weak Binding ◽  
Related Alkaloid ◽  
General Preference ◽  
Nitrogen Ring ◽  
Derivatives Of

Coralyne has been shown previously to bind well to both T∙A∙T- and C∙G∙C+-containing triplexes. Derivatives of coralyne were prepared and their binding to poly(dT)∙poly(dA)∙poly(dT) and poly[d(TC)]∙poly[d(GA)]∙poly[d(C+T)] was assessed from thermal denaturation profiles. A tetraethoxy derivative showed only weak binding to both types of triplex. Analogues with extended 8-alkyl chains showed good binding to poly(dT)∙poly(dA)∙poly(dT), but the preference for triplex poly[d(TC)]∙poly[d(GA)]∙poly[d(C+T)] was decreased compared with the duplex. Sanguinarine, a related alkaloid, bound well to poly(dT)∙poly(dA)∙poly(dT) but only weakly to the protonated triplex. It is hypothesized that the position of the protonated nitrogen ring is important for binding to poly[d(TC)]∙poly[d(GA)]∙poly[d(C+T)]. A series of other chromophores was studied and only those with a positive charge bound to triplexes. All of these bound well to poly(dT)∙poly(dA)∙poly(dT) but only weakly if at all to the duplex poly(dA)∙poly(dT). In contrast, most of them did not bind well to the triplex poly[d(TC)]∙poly[d(GA)]∙poly[d(C+T)] and those that did still showed a preference for duplex poly[d(TC)]∙poly[d(GA)]. In general, preference for triplex poly(dT)∙poly(dA)∙poly(dT) compared with the duplex is a common feature of intercalating drugs. On the other hand, specificity for protonated triplexes may be very difficult to achieve.Key words: triplex DNA, DNA-binding drugs, intercalation.

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