Époxydes α-éthyléniques et phénate de sodium: accès à des éthers phénoliques et phénols ortho-allyliques

1985 ◽  
Vol 63 (9) ◽  
pp. 2449-2454 ◽  
Author(s):  
Michèle David ◽  
Jean Sauleau ◽  
Armelle Sauleau
Keyword(s):  
Double Bond ◽  
Carbon Atom ◽  
Steric Hindrance ◽  
Transition States ◽  
Ring Cleavage ◽  
Reaction Conditions ◽  
Carbon Compounds ◽  
Judicious Choice ◽  
Ethylenic Carbon ◽  
Cleavage Reactions

The ring cleavage reactions of α-ethylenic epoxides by sodium phenoxide afforded a mixture of products. Problems of competitive attack by this nucleophile, at the less substituted carbon (compounds A) or at the β-ethylenic carbon atom (compounds B and C), were encountered and could be resolved by judicious choice of reaction conditions (solvents, stereochemistry of the oxiranes). The regioselectivity of the attack was dependent on the transition states, implying weak steric hindrance and a conjugation oxirane – double bond.

Cleavage of the Epimines of 1,6-Anhydrohexoses with Fluoride Anion

2005 ◽  
Vol 70 (12) ◽  
pp. 2075-2085 ◽  
Author(s):  
Jiří Kroutil ◽  
Klára Jeništová
Keyword(s):  
Fluoride Anion ◽  
Ring Cleavage ◽  
Protecting Group ◽  
Reaction Conditions ◽  
Aziridine Ring ◽  
Cleavage Reactions ◽  
Derivatives Of ◽  
Fluoro Derivatives

Aziridine ring cleavage reactions of five N-nosylepimines (2-6) having D-talo, D-galacto, D-manno, and D-allo configurations with potassium hydrogendifluoride under various reaction conditions have been performed. The cleavage regioselectively afforded diaxial isomers of vicinal amino-fluoro derivatives of 1,6-anhydro-β-D-gluco- and mannopyranose 7-11 in 51-94% yields. Removal of 2-nitrobenzenesulfonyl protecting group with benzenethiol has been attempted in the case of compound 10.

THEORETICAL STUDY OF THE REGIOSELECTIVITY OF THE ADDITION OF THE TRIPLET OXYGEN ATOM TO UNSYMMETRICAL SUBSTITUTED ALKENES

2012 ◽  
Vol 11 (03) ◽  
pp. 527-535 ◽  
Author(s):  
BOULANOUAR MESSAOUDI ◽  
SIDI MOHAMED MEKELLECHE ◽  
NELAINE MORA-DIEZ
Keyword(s):  
Double Bond ◽  
Carbon Atom ◽  
Oxygen Atom ◽  
Theoretical Study ◽  
Transition States ◽  
Reaction Pathways ◽  
Fukui Indices ◽  
Radical Attack ◽  
Spin Densities ◽  
Good Agreement

A theoretical study of the reactivity and regioselectivity of the addition of the triplet oxygen atom O(3P) to a series of unsymmetrical substituted alkenes has been performed at the PMP2/6-311++G (d,p) level of theory. Two reaction pathways, namely, the addition to the substituted carbon atom (α-site) and addition to the non-substituted carbon atom (β-site), have been studied. Our calculations show that the β-addition products are kinetically more favored; whereas the α-addition products are found to be thermodynamically more stable. The regioselectivity (α vs. β) of the addition of the O(3P) to the carbon–carbon double bond is predicted by means of the relative energies of the localized transition states and also by the calculation of spin densities of the 3ππ* states of reactants and Fukui indices corresponding to the radical attack to alkenes. Our calculations are in good agreement with experimental outcomes.

One-pot Synthesis of Pyrazolone Sulfones by Iodine-catalyzed Sulfenylation of Pyrazolones with Aryl Sulfonyl Hydrazides Followed by Oxidation in Water

2018 ◽  
Vol 15 (3) ◽  
pp. 380-387
Author(s):  
Xia Zhao ◽  
Xiaoyu Lu ◽  
Lipeng Zhang ◽  
Tianjiao Li ◽  
Kui Lu
Keyword(s):  
Double Bond ◽  
Efficient Method ◽  
Room Temperature ◽  
Sulfonyl Chloride ◽  
Antibacterial Activities ◽  
Oxidation Reactions ◽  
Reaction Conditions ◽  
One Pot ◽  
X Ray ◽  
Amide Form

Aim and Objective: Pyrazolone sulfones have been reported to exhibit herbicidal and antibacterial activities. In spite of their good bioactivities, only a few methods have been developed to prepare pyrazolone sulfones. However, the substrate scope of these methods is limited. Moreover, the direct sulfonylation of pyrazolone by aryl sulfonyl chloride failed to give pyrazolone sulfones. Thus, developing a more efficient method to synthesize pyrazolone sulfones is very important. Materials and Method: Pyrazolone, aryl sulphonyl hydrazide, iodine, p-toluenesulphonic acid and water were mixed in a sealed tube, which was heated to 100°C for 12 hours. The mixture was cooled to 0°C and m-CPBA was added in batches. The mixture was allowed to stir for 30 min at room temperature. The crude product was purified by silica gel column chromatography to afford sulfuryl pyrazolone. Results: In all cases, the sulfenylation products were formed smoothly under the optimized reaction conditions, and were then oxidized to the corresponding sulfones in good yields by 3-chloroperoxybenzoic acid (m-CPBA) in water. Single crystal X-ray analysis of pyrazolone sulfone 4aa showed that the major tautomer of pyrazolone sulfones was the amide form instead of the enol form observed for pyrazolone thioethers. Moreover, the C=N double bond isomerized to form an α,β-unsaturated C=C double bond. Conclusion: An efficient method to synthesize pyrazolone thioethers by iodine-catalyzed sulfenylation of pyrazolones with aryl sulfonyl hydrazides in water was developed. Moreover, this method was employed to synthesize pyrazolone sulfones in one-pot by subsequent sulfenylation and oxidation reactions.

Some Analogs of 4-(2',4'-Difluorobiphenyl-4-yl)-2-methyl-4-oxobutanoic Acid: Synthesis and Antiinflammatory Activity

1995 ◽  
Vol 60 (6) ◽  
pp. 1026-1033 ◽  
Author(s):  
Miroslav Kuchař ◽  
Václav Vosátka ◽  
Marie Poppová ◽  
Eva Knězová ◽  
Vladimíra Panajotovová ◽  
...  
Keyword(s):  
Double Bond ◽  
Antiinflammatory Activity ◽  
Acid Synthesis ◽  
Reaction Conditions ◽  
Methyl Group ◽  
Oxobutanoic Acid

Analogs of 4-(2',4'-difluorobiphenyl-4-yl)-2-methyl-4-oxobutanoic acid (I, flobufen), containing a double bond (II, IV, V, VII, VIII) or a methyl group in position 3 (VI) were prepared. Their antiinflammatory activity was evaluated and compared with that of flobufen. None of the mentioned analogs reached the activity of the standard. Isomerization of the unsaturated derivatives is connected with a shift of the double bond, Z-E transformation or lactonization. Reaction conditions and spectra of the compounds prepared are described.

Double bond isomerization of ethyl linoleate and vegetable oils to conjugated derivatives over an LDH supported ruthenium catalyst

RSC Advances ◽  
2015 ◽  
Vol 5 (45) ◽  
pp. 36075-36082 ◽  
Author(s):  
Sivashunmugam Sankaranarayanan ◽  
Gobi Selvam ◽  
Kannan Srinivasan
Keyword(s):  
Double Bond ◽  
Vegetable Oils ◽  
Ethyl Linoleate ◽  
Ruthenium Catalyst ◽  
Reaction Conditions ◽  
Double Bond Isomerization

Isomerization of ethyl linoleate and vegetable oils to conjugated derivatives is achieved over an MgAl-LDH supported ruthenium catalyst under mild reaction conditions.

Cleavage Reactions of 5-Arylazo Derivatives of 1-Methyl-2-benzyl-2-imidazolin-4-ones

1975 ◽  
Vol 30 (7-8) ◽  
pp. 603-605 ◽  
Author(s):  
Nazmi Abdel Latif Kassab ◽  
Abdel Hamid Harhash ◽  
Sanna Osman Abd Allah
Keyword(s):  
Sodium Hydroxide Solution ◽  
Aqueous Sodium Hydroxide ◽  
The Other ◽  
Ring Cleavage ◽  
Prolonged Heating ◽  
Aqueous Sodium Hydroxide Solution ◽  
Aqueous Sodium ◽  
Triazine Derivatives ◽  
Cleavage Reactions ◽  
Derivatives Of

The 5-arylazo-1-methyl-2-benzyl-2-imidazolin-4-ones (1 a-c) undergo ring cleavage with 1% aqueous sodium hydroxide solution affording α-arylhydrazono-phenacetyl-sarcosine amide (2). Prolonged heating of 1 and 2 with the same reagent yields the cyanamide (3). On the other hand, when 1 a-c were refluxed with acetic acid the triazinones (4) were obtained. The latter adds one mole of Grignards reagent to yield the 5-hydroxy-1,2,4-triazine derivatives (5).

New Ring Cleavage Reactions and Recyclizations Starting from 1,2,3-Thiadiazoles

1999 ◽  
Vol 153 (1) ◽  
pp. 427-428
Author(s):  
Wim Dehaen ◽  
Marieke Voets ◽  
Mario Smet ◽  
Stefan Smeets
Keyword(s):  
Ring Cleavage ◽  
Cleavage Reactions

ChemInform Abstract: Oxygen-Nucleophile-Induced Ring-Cleavage Reactions of 6-Methyl-1,3-oxazine-2,4(3H)-diones.

ChemInform ◽  
1988 ◽  
Vol 19 (13) ◽  
Author(s):  
H. SINGH ◽  
S. KUMAR
Keyword(s):  
Ring Cleavage ◽  
Cleavage Reactions

Reversible Cyclopropane Ring-Cleavage Reactions within Etheno-Bridged [4.3.1]Propelladiene Frameworks Leading to Aza- and Oxa-[5.6.5.6]fenestratetraenes

2012 ◽  
Vol 18 (43) ◽  
pp. 13585-13588 ◽  
Author(s):  
Nora Heinrich ◽  
Anthony C. Willis ◽  
Ian A. Cade ◽  
Junming Ho ◽  
Michelle L. Coote ◽  
...  
Keyword(s):  
Cyclopropane Ring ◽  
Ring Cleavage ◽  
Cleavage Reactions

Über Derivate des Hydrazins, VII Zur Reaktivität von Bis(trimethylsilyl)aminoisocyanid / On Derivatives of Hydrazine, VII Reactivity of Bis(trimethylsilyl)aminoisocyanide

1977 ◽  
Vol 32 (9) ◽  
pp. 1003-1009 ◽  
Author(s):  
Nils Wiberg ◽  
Gerhard Hübler
Keyword(s):  
Double Bond ◽  
Oxidation State ◽  
Ring Cleavage ◽  
Reaction Paths ◽  
Stable Compound ◽  
Oxidizing Agents ◽  
Formal Oxidation State ◽  
Double Bond System ◽  
Bond System ◽  
Derivatives Of

The chemistry of bis(trimethylsilyl)aminoisocyanide (1) is determined by three reactive centres of the system : the hydrolyzable Si–N-bond, the oxidizable carbon in the formal oxidation state two, the additionable double bond system. Reactions of the oxygen stable compound 1 with halogens X2 or sulfenyl halides RSX as oxidizing agents gives compounds of type (Me3Si)2NNCX2 or (Me3Si)2NNCX(SR). Heterocumulenes such as CO2, CS2, RNCS (R = (Me3Si)2N), SO2 add to 1, leading to heterocycles, which decompose at higher temperatures by ring cleavage. With other heterocumulenes such as PhNCO, Me3SiNSO, Me3SiNSNSiMe3 products are found, the formation of which could be explained by reaction paths including the building and cleavage of heterocycles.

Sign in / Sign up

Export Citation Format

Share Document