scholarly journals Intramolecular Metathesis of a Vinyl Group with Vinylidene CC Double Bond in Ru Complexes

2005 ◽  
Vol 127 (51) ◽  
pp. 18037-18045 ◽  
Author(s):  
Yung-Sheng Yen ◽  
Ying-Chih Lin ◽  
Shou-Ling Huang ◽  
Yi-Hung Liu ◽  
Hui-Ling Sung ◽  
...  
Keyword(s):  
Double Bond ◽  
Ru Complexes ◽  
Vinyl Group

scholarly journals Intramolecular Cyclization of Ruthenium Vinylidene Complexes with a Tethering Vinyl Group:  Facile Cleavage and Reconstruction of the C−C Double Bond

2007 ◽  
Vol 129 (48) ◽  
pp. 14974-14980 ◽  
Author(s):  
Cheng ◽  
Yi-Chun Kuo ◽  
Shu-Hao Chang ◽  
Ying-Chih Lin ◽  
Yi-Hong Liu ◽  
...  
Keyword(s):  
Double Bond ◽  
Intramolecular Cyclization ◽  
Vinylidene Complexes ◽  
Vinyl Group

scholarly journals Concerning the structure of photobilirubin II

1982 ◽  
Vol 201 (1) ◽  
pp. 179-188 ◽  
Author(s):  
M S Stoll ◽  
N Vicker ◽  
C H Gray ◽  
R Bonnett
Keyword(s):  
Double Bond ◽  
Starting Material ◽  
Vinyl Group

Evidence is presented which supports the postulate that the photobilirubins IIA and IIB are diastereoisomers in which the C-3 vinyl group has cyclized intramolecularly. The evidence comes principally from proton n.m.r. spectroscopy at 400 MHz and from chemical considerations. The cyclic structures require the E-configuration at the C-4 double bond in the precursor; this is the first structural evidence for the Z leads to E isomerization in bilirubin and supports the view that the precursor (photobilirubin IA or IB) is (4E, 15Z)-bilirubin. Brief irradiation of photobilirubin II gives bilirubin, a new compound (photobilirubin III) and unchanged starting material. The various photoisomers are discussed in terms of their inter-relationships and biological fates.

Electrophilic additions to 10β-vinyl cholestane derivatives

1983 ◽  
Vol 48 (10) ◽  
pp. 2994-3019 ◽  
Author(s):  
Pavel Kočovský ◽  
Ivo Starý ◽  
František Tureček ◽  
Vladimír Hanuš
Keyword(s):  
Reaction Mechanism ◽  
Double Bond ◽  
Hydroxyl Group ◽  
Acid Addition ◽  
Hypobromous Acid ◽  
Markovnikov Rule ◽  
Vinyl Group ◽  
Electrophilic Additions

Hypobromous acid addition to steroid dienes I-VI proceeds in four steps. The reaction commences by the attack on more reactive endocyclic double bond from the α-side yielding intermediary diaxial bromohydrins XXVIII, XXXIV, XL, XLIV, L and LVI via corresponding α-bromonium ions. The 10β-vinyl group of the bromohydrins then reacts with a second equivalent of the reagent forming transient 19-epimeric bromonium ions. The ions generated from I, II, V and VI are cleaved intramolecularly by the hydroxyl group, in accordance with the Markovnikov rule, giving rise to 19-epimeric dibromo epoxides XXXIa and XXXIIa, XXXVII and XXXVIII, LIIIa and LIVa, LIX and LX. By contrast, the ions generated from III and IV are cleaved in an anti-Markovnikov manner to yield dibromo epoxides XLII, XLVII and XLVIII. Products due to formation of a new C-C bond were not observed. The reaction mechanism and differences in the behaviour of the dienes I-VI are discussed.

Silaheterocyclen, XIII Erzeugung und Cycloadditionsverhalten von 1,3-Diaza-2,4-disila-und 1.3-Disilacyclobutanen mit exocyclischer SiC-Doppelbindung Silaheterocycles, XIII / Formation and Cycloaddition Reactions of 1,3-Diaza-2,4-disila-and 1.3-Disilacyclobutanes Containing an Exocyclic SiC Double Bond

1992 ◽  
Vol 47 (2) ◽  
pp. 217-230 ◽  
Author(s):  
Norbert Auner ◽  
Erika Penzenstadler
Keyword(s):  
Double Bond ◽  
Diels Alder ◽  
Spiro Compound ◽  
Cycloaddition Reactions ◽  
Temperature Range ◽  
Vinyl Group ◽  
Trapping Agent

The silenes A and B are formed by reacting 1,3-ditbutyl-2,4-dichloro-2,4-divinyl-1,3-diaza- 2.4-disilacyclobutane (2) and 1,3-dichloro-2,4-dineopentyl-1,3-divinyl-1,3-disilacyclobutane (15) with LiBut in n-pentane in the temperature range from −10 to 0 °C. The reaction primarily leads to the corresponding α-lithioadducts (addition of LiBut to the vinyl group of 2 and 15), and with subsequent 1,2-LiCl elimination yields A and B as intermediates. A can be trapped by polar reagents Me3SiX (X = OMe, OSO2CF3) as well as by organic dienes which add across the Si = C bond; in the absence of a trapping agent the spiro compound 6 is isolated. The silenes A and B differ in their cycloaddition behaviour to butadienes, norbornadiene and cyclohexa-1,3-diene: Whereas for A the regioselective [2 + 2]-cycloaddition to yield monosilacyclobutane derivatives is preferred due to electronic reasons, the reaction of B leads mainly to Diels-Alder products. Thus, A is quite comparable in its reactivity to dichloroneopentylsilene, while B reacts like its diorgano substituted analogues R2Si = CHCH2But (R = Me, But or Ph).

THE THYMOLYTIC ACTIVITY OF 6- AND 9-HALOCORTICOIDS AND RELATED STEROIDS

1965 ◽  
Vol 49 (2) ◽  
pp. 262-270 ◽  
Author(s):  
Ralph I. Dorfman ◽  
P. G. Holton ◽  
Fred A. Kind
Keyword(s):  
Double Bond ◽  
Subcutaneous Injection ◽  
Fluocinolone Acetonide ◽  
Relative Potency ◽  
Subcutaneous Route ◽  
Adrenalectomized Rats

ABSTRACT Adrenalectomized rats were used for the determination of the relative potency of various 6- and 9-halo substituted corticoids administered subcutaneously or by gavage using thymus weightas the endpoint. By subcutaneous injection, fluocinolone acetonide was the most active corticoid at 700 times that of cortisol. This compound was also the most active corticoid by the gavage route and was judged to be 570 times as active as the standard cortisol. The introduction of the 16,17-acetonide and 16,17-acetone 21-acetate groups into 17α,21-dihydroxy-9α,11β-dichloropregna-1,4-diene-3,20-dione increased the activity by a factor of 42 and 100, respectively. The introduction of the δ1 double bond into 6α-fluoroprogesterone 16,17-acetonide caused an increase of 10-fold in thymolytic activity assessed by the subcutaneous route

Ruthenium(II) Complexes Bearing Thioether-Appended α- Iminopyridine Ligands: Arene Precursors Permit Access to K2-N,N and K3-N,N,S Complexes

2019 ◽  
Author(s):  
Victoria A. Ternes ◽  
Hannah A. Morgan ◽  
Austin P. Lanquist ◽  
Michael P. Murray ◽  
Bradley Wile
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Strong Field ◽  
Active Role ◽  
Binding Mode ◽  
Phenethyl Alcohol ◽  
Ru Complexes

Herein we report the preparation of a series of Ru(II) complexes featuring alpha-iminopyridine ligands bearing thioether functionality (NNS<sup>R</sup>, where R = Me, CH<sub>2</sub>Ph, Ph). Metallation using (<i>p</i> cymene)RuCl dimer permits access to (k<sup>2</sup>-N,N)Ru complexes in which the thioether moiety remains uncoordinated. In the presence of a strong field ligand such as acetonitrile or triphenylphosphine, the p-cymene moiety is displaced, and the ligand adopts a k<sup>3</sup>-N,N,S binding mode. These complexes are characterized using a combination of solution and solid state methods, including the crystal structure of [(NNS<sup>Me</sup>)Ru(NCMe)<sub>2</sub>Cl]Cl. The k<sup>2</sup>-N,N Ru(II) complexes are shown to serve as efficient precatalysts for the oxidation of sec-phenethyl alcohol at 5 mol% loadings, using a variety of external oxidants and solvents. The complex bearing an S-Ph donor was found to be the most active of those surveyed, suggesting that the thioether donor plays an active role in catalyst speciation for this transformation.

TRIGLYCERIDE COMPOSITION OF SIXTEEN STRAINS OF MARINE DIATOM

2013 ◽  
Vol 5 (1) ◽  
Author(s):  
Lily M.G. Panggabean ◽  
Abdullah Rasyid ◽  
Zarrah Duniani ◽  
Yana Meliana ◽  
Indah Kurniasih
Keyword(s):  
Mass Spectrometry ◽  
Fatty Acid ◽  
Double Bond ◽  
Unsaturated Fatty Acid ◽  
Ion Trap ◽  
Carbon Chain ◽  
Highly Unsaturated Fatty Acid ◽  
Marine Diatom ◽  
Ion Trap Mass Spectrometry ◽  
Spectra Analysis

Trigliceride or triacylglicerol (TAG) composition in crude oil of sixteen strain of marine diatom has been detected by spectra analyses on an Electrospray - Ion Trap – Mass Spectrometry (ESI-IT-MS) HCT Bruker-Daltonic GmbH instrument with AgNO3 used as coordination ionization agent. Biomass samples of each microalga strain were taken from early and late stationary cultures in f/2 enriched seawater and algal oils were extracted according to Bligh and Dyer. Results from spectra analysis showed that P-Pt-P (C16:0-C16:1-C16:0) were distinguished in TAG from diatom strains Chaetoceros sp.1, Chaetoceros sp.2, Thalasiossira sp.1, Thalasiossira sp.2, Thalasiossira sp.3, Navicula sp. 1, Navicula sp. 2, Navicula sp. 3, Navicula sp. 4, Nitzschia sp. 2 and Amphora sp. In contrast, TAGs in Melosira sp. included P-P-P (C16:0-C16:0-C16:0) and P-P-O (C16:0-C16:0-C18:1) were identified. TAGs from Chaetoceros sp. were the most varies among samples, i.e. P-Pt-P (C16:0-C16:1-C16:0), A-P-M (C20:4-C16:0-C14:0), P-Pt-Lt (C16:0-C16:1-C18:3), P-Pt-A (C16:0-C16:1-C20:4), D-P-P (C22:6-C16:0-C16:0), A-Ln-P (C20:4-C18:2-C16:0). Various TAGs were also detected in Nitzschia sp.2, i.e. P-Pt-M (C16:0-C16:1-C14:0), P-Pt-P (C16:0-C16:1-C16:0), P-Pt-S (C16:0-C16:1-C18:0), P-Pt-A (C16:0-C16:1-C20:4). TAGs composition in Skeletonema strains that similar to those in Nitzschia sp.1 has longer carbon, i.e. P-P-O (C16:0-C16:0-C18:1), P-O-O (C16:0-C18:1-C18:1) and O-O-O (C18:1-C18:1-C18:1). TAGs with longer carbon chain and more double bond including highly unsaturated fatty acid C20:4 were increased with culture age in diatoms Chaetoceros sp.1, Chaetoceros sp.2, Thalasiossira sp.2, Navicula sp.1 and Nitzschia sp. 2.Keywords: diatom, TAG, ESI-IT-MS, f/2, early and late stationary

Some Considerations Regarding the 1H and 13C Spectra of 4-(1-azulenyl)-2,6-bis(2-heteroaryl-vinyl)- pyrylium and Pyridinium and their Corresponding Pyridines

2018 ◽  
Vol 69 (1) ◽  
pp. 64-69
Author(s):  
Liviu Birzan ◽  
Mihaela Cristea ◽  
Constantin C. Draghici ◽  
Alexandru C. Razus
Keyword(s):  
Double Bond ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Pyridinium Salts ◽  
13C Nmr Spectra ◽  
1H And 13C Nmr ◽  
Pyrylium Salts

The 1H and 13C NMR spectra of several 2,6-diheteroarylvinyl heterocycles containing 4-azulenyl moiety were recorded and their proton and carbon chemical shifts were compared with those of the compounds without double bond between the heterocycles. The influence of the nature of central and side heterocycles, molecule polarization and anisotropic effects were revealed. The highest chemical shifts were recorded for the pyrylium salts and the lowest at pyridines, but in the case of the pyridinium salts, the protons chemical shifts at the central heterocycle are more shielded due to a peculiar anisotropy of the attached vinyl groups.

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