scholarly journals Attempted Synthesis and Unexpected β-Fragmentation of a Hindered β-Keto Nitroxide

2017 ◽  
Vol 70 (10) ◽  
pp. 1106 ◽  
Author(s):  
Chris Edwards ◽  
Peter C. Healy ◽  
W. Ken Busfield ◽  
Ezio Rizzardo ◽  
San H. Thang ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Ring Opening ◽  
Sodium Tungstate ◽  
Crystallographic Analysis ◽  
High Yield ◽  
Fragmentation Mechanism ◽  
Pentanoic Acid ◽  
X Ray ◽  
Ring Opening Reaction

The attempted synthesis of a β-keto imidazolidinone nitroxide by oxidation of the β-hydroxy imidazolidinone precursor with hydrogen peroxide and sodium tungstate led to an unexpected ring-opening reaction to produce 1,4-diazaspiro[4.5]dec-1-en-3-oxo-2-pentanoic acid 1-oxide (13) in high yield. The structure of 13 was confirmed by X-ray crystallographic analysis. A β-fragmentation mechanism is suggested for the oxidative ring-opening reaction.

scholarly journals Synthesis of Octahydropyrano[2,3-d]Pyrimidine Derivatives via Tetrahydropyrano[3,2-e][1,3]Thiazolo[3,2-a]Pyrimidine and 2,6-Dichlorobenzonitrile Oxide

2018 ◽  
Vol 42 (6) ◽  
pp. 317-319
Author(s):  
Qing Zeng ◽  
Demin Ren ◽  
Aiting Zheng ◽  
Xiaofang Li
Keyword(s):  
Ring Opening ◽  
Crystallographic Analysis ◽  
Dipolar Cycloaddition ◽  
Pyrimidine Derivatives ◽  
X Ray ◽  
Moderate Yield

N1-substituted octahydro-1 H-pyrano[2,3- d]pyrimidines derivatives were prepared in moderate yield by the reaction of methyl [(4a RS,5 SR,10a RS)-5-aryl-2-oxo-3,4,4 a,10 a-tetrahydro-2 H,5 H-pyrano[3,2- e][1,3]thiazolo[3,2- a]pyrimidin-8(9 H)-ylidene]acetate and 2,6-dichorobenzonitrile oxide via a domino 1,3-dipolar cycloaddition/ring-opening/dethionation process. The structures of the products were characterised by spectroscopic and X-ray crystallographic analysis.

The direct electrochemical synthesis of thiolato complexes of cobalt and nickel, and the crystal structure of bis(phenylthiolato)bis(1,10-phenanthroline)cobalt(III) perchlorate

1988 ◽  
Vol 66 (9) ◽  
pp. 2151-2156 ◽  
Author(s):  
Raj K. Chadha ◽  
Rajesh Kumar ◽  
Jaime Romero Lopez-Grado ◽  
Dennis G. Tuck
Keyword(s):  
Crystal Structure ◽  
Electrochemical Oxidation ◽  
Electrochemical Synthesis ◽  
Crystallographic Analysis ◽  
High Yield ◽  
X Ray ◽  
Metal Anode ◽  
Aerial Oxidation ◽  
Perchlorate Salt ◽  
Cobalt And Nickel

Cobalt(II) and nickel(II) thiolates, M(SR)2, can be prepared in high yield by the electrochemical oxidation of a metal anode in an acetonitrile or acetone solution of RSH (R = C6H5, o-CH3C6H4, 2-C10H7, 2,3,4,5-C6F4H; not all combinations). When 2,2-bipyridine or 1,10-phenanthroline (=L) is added to the electrolyte phase, the products are the adducts M(SR)2L2. In the case of Co(SC6H5)2(phen)2, aerial oxidation leads to the formation of the cobalt(III) cation [Co(SC6H5)2(phen)2]+, isolated as the perchlorate salt. X-ray crystallographic analysis showed that this cation has a cis-CoS2(N2)2 kernel.

scholarly journals Synthesis of Some Biologically Important 3-Oxacepham Derivatives

1970 ◽  
Vol 5 (1) ◽  
pp. 47-51 ◽  
Author(s):  
Mohammad Rafiqul Islam ◽  
Mohammad Nurnabi ◽  
AM Sarwaruddin Chowdhury ◽  
Mohammad Mehdi Masud
Keyword(s):  
Key Words ◽  
Full Text ◽  
Crystallographic Analysis ◽  
High Yield ◽  
Methyl Group ◽  
X Ray ◽  
Tert Butyl ◽  
Relative Stereochemistry

The 6H-oxathiazines 1a-e having imine moiety underwent [2+2] cycloaddition with phenoxyacetylchloride in the presence of Et3N to give β-lactam derivatives 2a-e in high yield. The X-ray crystallographic analysis revealed the relative stereochemistry that the substituents at C-2 and C-4 were cis configurated. The subtituents at C-6 and C-7 were also cis to each other. However, the 6H-oxathiazines 1f-i containing tert-butyl or methyl group at C-4 did not undergo the cycloaddition. Key words: Azetedinone, β-lactam, oxacepham, cycloaddition, imine, ketene, oxathiazine. Dhaka Univ. J. Pharm. Sci. Vol.5(1-2) 2006 The full text is of this article is available at the Dhaka Univ. J. Pharm. Sci. website

Synthesis of 2,3-Anhydro Glycosyl Phosphonates

1996 ◽  
Vol 49 (3) ◽  
pp. 371 ◽  
Author(s):  
m Doanxuanlie ◽  
ID Jenkins ◽  
BW Skelton ◽  
AH White
Keyword(s):  
Hydrogen Peroxide ◽  
Structural Analysis ◽  
Sodium Tungstate ◽  
X Ray

The synthesis of dimethyl 6-O-acetyl-2,3-anhydro-α-D- mannopyranosylphosphonates and the corresponding α- and β- allo derivatives is described. Dimethyl 4,6-di-O-acetyl-2,3-dideoxy-D-erythro-hex-2-enopyranosylphosphonates, although unreactive towards normal epoxidizing agents (3-chloroperoxybenzoic acid, trifluoroperoxyacetic acid, etc), underwent smooth epoxidation with hydrogen peroxide in the presence of sodium tungstate or dodecatungstophosphoric acid. An interesting regiospecific deacetylation of the 4-acetate occurred under these conditions. The structures of these anhydro glycosyl phosphonates were determined by 1H and 13C n.m.r. spectroscopy, and confirmed by X ray structural analysis in the case of dimethyl 6-O-acetyl-2,3-anhydro-α-D-mannopyranosylphosphonate , and of dimethyl 6-O-acetyl-2,3-anhydro-β-D-allopyranosylphosphonate.

Dihydropyridines in synthesis and biosynthesis. III. Coupling of dihydropyridinetricarbonylchromium(0) complexes: bipyridyls

1982 ◽  
Vol 60 (3) ◽  
pp. 323-326 ◽  
Author(s):  
James P. Kutney ◽  
Lucas Kaczmarek ◽  
Danuta Mostowicz ◽  
Brian R. Worth
Keyword(s):  
Low Temperature ◽  
Crystallographic Analysis ◽  
High Yield ◽  
X Ray ◽  
Methyl Pyridine

Reaction of 1,2- and 1,6-dihydro-3-ethyl-N-methyl pyridine tricarbonylchromium(0) complexes with methyllithium at low temperature afforded a high yield of dimeric tricarbonylchromium(0) complexes. Structures of the latter products were established by X-ray crystallographic analysis. Some chemistry of these novel compounds is described.

scholarly journals Non-Isocyanate Polyurethane (NIPU) based on Rubber Seed Oil Synthesized via Low-Pressured Carbonization Reaction

2021 ◽  
Vol 50 (8) ◽  
pp. 2407-2417
Author(s):  
R.A. Hambali ◽  
M.A. Faiza ◽  
A. Zuliahani
Keyword(s):  
Hydrogen Peroxide ◽  
Double Bond ◽  
Formic Acid ◽  
Ring Opening ◽  
Seed Oil ◽  
Epoxide Ring ◽  
Rubber Seed Oil ◽  
Rubber Seed ◽  
Ring Opening Reaction ◽  
Epoxidation Reaction

Epoxidised rubber seed oil (ERSO) was successfully synthesized into non-isocyanate polyurethane via carboxylation method whereas peroxoformic acid was formed by in-situ reaction for epoxidation. The effects of temperature and ratio of hydrogen peroxide and formic acid to rubber seed oil carboxylation were studied. The optimum temperature for the epoxidation reaction was found at 50 °C to avoid ring opening reaction of epoxy whilst the optimum ratio of hydrogen peroxide and formic acid is equal molar of double bond: formic acid at 1:2 and 1:1, respectively. At a lower concentration of hydrogen peroxide and formic acid, the oxirane ring was stable due to the lower hydrolysis (oxirane cleavage) of an epoxide. The effect of using low content of formic acid tends to minimize unwanted epoxide ring opening to occur and make the epoxidation rate increased with increasing of oxirane number. Fourier transform infrared (FTIR) spectral displayed the presence of an epoxy functional group at 822 cm-1 and the disappearance of double bond peak at 3011 cm-1 corresponding to epoxidised oil and carbonyl group confirmed the epoxidation reaction had taken place. 1H-NMR was used to confirm the formation of carboxylate functionality after the reaction of epoxy at δ 4.83 and 4.61 ppm. In conclusion, ERSO has great potential to be used as a precursor in producing environmentally friendly non-isocyanate polyurethane.

scholarly journals Femtosecond x-ray spectroscopy of an electrocyclic ring-opening reaction

Science ◽  
2017 ◽  
Vol 356 (6333) ◽  
pp. 54-59 ◽  
Author(s):  
Andrew R. Attar ◽  
Aditi Bhattacherjee ◽  
C. D. Pemmaraju ◽  
Kirsten Schnorr ◽  
Kristina D. Closser ◽  
...  
Keyword(s):  
Ring Opening ◽  
X Ray ◽  
Ring Opening Reaction

scholarly journals Hydrophobic Modification of Nanocellulose via a Two-Step Silanation Method

Polymers ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1035 ◽  
Author(s):  
Wensheng Lin ◽  
Xiaoyong Hu ◽  
Xueqing You ◽  
Yingying Sun ◽  
Yueqin Wen ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Photoelectron Spectroscopy ◽  
Ring Opening ◽  
Chemical Characteristics ◽  
Surface Chemical ◽  
Hydrophobic Modification ◽  
Step Method ◽  
Water Contact ◽  
X Ray ◽  
Ring Opening Reaction

Dodecyltrimethoxysilane (DTMOS), which is a silanation modifier, was grafted onto nanocellulose crystals (NCC) through a two-step method using KH560 (ɤ-(2,3-epoxyproxy)propytrimethoxysilane) as a linker to improve the hydrophobicity of NCC. The reaction mechanism of NCC with KH560 and DTMOS and its surface chemical characteristics were investigated using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and HCl–acetone titration. These analyses confirmed that KH560 was grafted onto the surface of NCC through the ring-opening reaction, before DTMOS was covalently grafted onto the surface of NCC using KH560 as a linker. The grafting of NCC with DTMOS resulted in an improvement in its hydrophobicity due to an increase in its water contact angle from 0° to about 140°. In addition, the modified NCC also possessed enhanced thermal stability.

Synthesis and Structure of the Potassium Salt with Monodeprotonated 1,2,3-Tri(ethoxycarbonylpropyl)-p-t-butylcalix[6]arene

2008 ◽  
Vol 61 (7) ◽  
pp. 537 ◽  
Author(s):  
Ze-Bao Zheng ◽  
Ren-Tao Wu ◽  
Ji-Kun Li ◽  
Yi-Feng Sun
Keyword(s):  
Potassium Salt ◽  
Crystallographic Analysis ◽  
Potassium Ion ◽  
High Yield ◽  
Cone Conformation ◽  
X Ray ◽  
Partial Cone ◽  
Phenyl Rings ◽  
Close Contacts

Alkylation of p-t-butylcalix[6]arene with ethyl 4-bromobutanoate in the presence of K2CO3 results in a potassium salt of the monodeprotonated 1,2,3-tri(ethoxycarbonylpropyl)-p-t-butylcalix[6]arene in high yield. X-Ray crystallographic analysis shows that this compound exists as a double partial cone conformation. The potassium ion is positioned near the centre of the cavity of the macrocycle and binds to four phenolic oxygens. Close contacts between the potassium ion and phenyl rings observed in this compound are indicative of the presence of the cation–π interaction. The molecules are connected via intermolecular K+···O interactions into infinite chains.

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