scholarly journals Photochemical approach to functionalized benzobicyclo[3.2.1]octene structures via fused oxazoline derivatives from 4- and 5-(o-vinylstyryl)oxazoles

2014 ◽  
Vol 10 ◽  
pp. 2222-2229 ◽  
Author(s):  
Ivana Šagud ◽  
Simona Božić ◽  
Željko Marinić ◽  
Marija Šindler-Kulyk
Keyword(s):  
Silica Gel ◽  
Ring Opening ◽  
Spectroscopic Methods ◽  
Intramolecular Cycloaddition ◽  
Wittig Reactions ◽  
Van Leusen Reaction ◽  
Oxazoline Derivatives

Novel cis/trans-4- and cis/trans-5-(2-vinylstyryl)oxazoles have been synthesized by Wittig reactions from the diphosphonium salt of α,α’-o-xylene dibromide, formaldehyde and 4- and 5-oxazolecarbaldehydes, respectively. In contrast, trans-5-(2-vinylstyryl)oxazole has been synthesized by the van Leusen reaction from trans-3-(2-vinylphenyl)acrylaldehyde which is prepared from o-vinylbenzaldehyde and (formylmethylene)triphenylphosphorane. The 4- and 5-(2-vinylstyryl)oxazoles afford, by photochemical intramolecular cycloaddition, diverse fused oxazoline-benzobicyclo[3.2.1]octadienes, which are identified and characterized by spectroscopic methods. The photoproducts formed are relatively unstable and spontaneously or on silica gel undergo oxazoline ring opening followed by formation of formiato- or formamido-benzobicyclo[3.2.1]octenone derivatives. On irradiation of 4-(2-vinylstyryl)oxazole small quantities of electrocyclization product, 4-(1,2-dihydronaphthalen-2-yl)oxazole, are isolated and spectroscopically characterized.

Derivatives of isatin in aqueous solution. I. Kinetics of ring opening of Isatin-5-sulfonate

1981 ◽  
Vol 34 (2) ◽  
pp. 365 ◽  
Author(s):  
H Stunzi
Keyword(s):  
Ring Opening ◽  
Rate Of Change ◽  
Spectroscopic Methods ◽  
Ph Values ◽  
Buffer Region ◽  
Pka Value ◽  
Back Titration ◽  
Kinetics Of ◽  
Derivatives Of ◽  
Sulfonate Anion

The reactions of isatin-5-sulfonate anion (si-) which cause a hysteresis in pH titrations were studied by pH-metric and n.m.r, spectroscopic methods. Rapid alkalimetric titrations [I 0.15 M (KNO3),37�] gave the pKa value corresponding to the addition of OH- to si- [pKa(ring) 9.55]. The slow ring opening to the sulfonatoisatate dianion (sia2-) led to a drift of the pH values towards an equilibrium buffer region. Its pKa, value [pKa(eq) 3.44] corresponds to the reaction si-+H2O ↔ sia 2-+H+ Rapid back-titration gave the pKa value of the ring-opened species Hsia- [pKa(open) c. 1.3]. The rate law for the ring opening d[sia]/dt=k2 [siOH](OH)+k1*[si] was obtained from the rate of change of pH. N-Methylisatin-5-sulfonate behaves analogously.

Total Synthesis of Resolvin T4

Synlett ◽  
2021 ◽  
Author(s):  
Narihito Ogawa ◽  
Kohei Arai ◽  
Yuichi Kobayashi
Keyword(s):  
Total Synthesis ◽  
Ring Opening ◽  
Transfer Hydrogenation ◽  
Asymmetric Transfer Hydrogenation ◽  
Ring Opening Reaction ◽  
Propargylic Alcohol ◽  
Chiral Centers ◽  
Wittig Reactions

AbstractA total synthesis of resolvin T4 was achieved by connecting three intermediates by Wittig reactions. The enal in the C1–C10 part was constructed through reduction of a propargylic alcohol with Red-Al followed by oxidation. The enal moiety in the C11–C16 part was synthesized by a ring-opening reaction of a silyl epoxide followed by a Peterson elimination. The chiral centers at C7 and C13 were constructed by ruthenium-catalyzed asymmetric transfer hydrogenation.

Silica gel modified with lumogallion for aluminum determination by spectroscopic methods

Talanta ◽  
2005 ◽  
Vol 67 (4) ◽  
pp. 767-772 ◽  
Author(s):  
O NADZHAFOVA ◽  
O ZAPOROZHETS ◽  
I RACHINSKA ◽  
L FEDORENKO ◽  
N YUSUPOV
Keyword(s):  
Silica Gel ◽  
Spectroscopic Methods

Practical Preparation of Diosphenols by Ring Opening of α,β-Epoxyketones Catalyzed by Silica Gel Supported Acids.

ChemInform ◽  
2007 ◽  
Vol 38 (52) ◽  
Author(s):  
Rui Zhu ◽  
Lixin Xing ◽  
Xinyan Wang ◽  
Chuanjie Cheng ◽  
Bo Liu ◽  
...  
Keyword(s):  
Silica Gel ◽  
Ring Opening

Practical Preparation of Diosphenols by Ring Opening of α,β-Epoxyketones Catalyzed by Silica Gel Supported Acids

Synlett ◽  
2007 ◽  
Vol 2007 (14) ◽  
pp. 2267-2271 ◽  
Author(s):  
Yuefei Hu ◽  
Rui Zhu ◽  
Lixin Xing ◽  
Xinyan Wang ◽  
Chuanjie Cheng ◽  
...  
Keyword(s):  
Silica Gel ◽  
Ring Opening

Chemical Constituents from Euphorbia helioscopia

2011 ◽  
Vol 396-398 ◽  
pp. 1337-1340 ◽  
Author(s):  
Di Geng ◽  
Lian Jin Weng ◽  
Yuan Yuan Han ◽  
Xin Yang
Keyword(s):  
Silica Gel ◽  
Chemical Constituents ◽  
2D Nmr ◽  
Spectroscopic Methods ◽  
Nmr Spectrum ◽  
Euphorbia Helioscopia ◽  
First Time ◽  
Spectrum Data

AIM: To study the chemical constituents of Euphorbia helioscopia. METHODS: Compounds 1-10 were isolated and purified by silica gel, Sephadex LH-20 and Rp-18 chromatogarphy. Their structures were elucidated mainly by spectroscopic methods. RESULTS: Ten known compounds, helioscopinolide A(1), helioscopinolide B(2), scopoletin(3), scoparone(4), isoscopoletin(5), licochalone A(6), quercelin(7), 7, 4’-dihydroxy-5-methoxy flacanone(8), 2’, 4’-dihydroxy-6’-methoxydihydrochalcone(9) and pinocembrin(10), were isolated and structurally elucidated. CONCLUSION: Compound 3-5 and 8-10 were isolated from this plant for the first time. 2D NMR spectrum data of 2 were also reported in this paper.

scholarly journals Anionic Copolymerization of Styrene Sulfide with Elemental Sulfur (S8)

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2597
Author(s):  
Jakub Wręczycki ◽  
Dariusz M. Bieliński ◽  
Marcin Kozanecki ◽  
Paulina Maczugowska ◽  
Grzegorz Mlostoń
Keyword(s):  
Thermal Stability ◽  
Raman Spectroscopy ◽  
Ring Opening ◽  
Chemical Structure ◽  
Elemental Sulfur ◽  
Ring Opening Polymerization ◽  
Spectroscopic Methods ◽  
Initial Ratio ◽  
Anionic Copolymerization ◽  
Thermal Stability Of

The superior ability of thiiranes (episulfides) to undergo ring-opening polymerization (ROP) in the presence of anionic initiators allows the preparation of chemically stable polysulfide homopolymers. Incorporation of elemental sulfur (S8) by copolymerization below the floor temperature of S8 permits the placement of a large quantity of sulfur atoms in the polysulfide mainchain. The utility of styrene sulfide (2-phenylthiirane; StS) for copolymerization with elemental sulfur is reported here. A few polysulfides differing depending on the initial ratio of S8 to StS and copolymerization time were synthesized. Various spectroscopic methods (1H NMR, 13C NMR, Raman spectroscopy and FTIR spectroscopy) were applied to characterize the chemical structure of the copolymers. Additionally, the phase structure and thermal stability of the synthesized polysulfides were investigated using DSC and TGA, respectively. The successful anionic copolymerization of styrene sulfide and elemental sulfur has been demonstrated.

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