The Reaction between β-Keto Esters and Arylamines in the Presence of Polyphosphoric Acid. II.1Ethyl Acetoacetate and Its α-Alkyl Derivatives and Arylamines

1964 ◽  
Vol 29 (12) ◽  
pp. 3548-3555 ◽  
Author(s):  
A. K. Mallams ◽  
S. S. Israelstam
Keyword(s):  
Polyphosphoric Acid ◽  
Keto Esters ◽  
Alkyl Derivatives

Fluorinated tricyclic neuroleptics with prolonged action: 8-Alkyl derivatives of 3-fluoro-10-piperazino-10,11-dihydrodibenzo[b,f]thiepins

1984 ◽  
Vol 49 (11) ◽  
pp. 2638-2648 ◽  
Author(s):  
Jiří Jílek ◽  
Miroslav Rajšner ◽  
Jiřina Metyšová ◽  
Josef Pomykáček ◽  
Miroslav Protiva
Keyword(s):  
Polyphosphoric Acid ◽  
Titanium Tetrachloride ◽  
Prolonged Action ◽  
Substitution Reactions ◽  
Piperazine Derivatives ◽  
Alkyl Derivatives ◽  
Chloro Derivatives ◽  
Derivatives Of ◽  
By Products ◽  
Hydroxyethyl Piperazine

Reactions of (4-fluoro-2-iodophenyl)acetic or (2-bromo-4-fluorophenyl)acetic acid with 4-methylthiophenol, 4-ethylthiophenol and 4-isopropylthiophenol under various conditions afforded the acids IIIa-c which were cyclized with polyphosphoric acid to 8-alkyl-3-fluorodibenzo-[b,f]thiepin-10(11H)-ones IVa-c. The alcohols Va-c, which were obtained by reduction of the ketones with sodium borohydride, were transformed by treatment with hydrogen chloride to the chloro derivatives Via-c. Their substitution reactions with 1-methylpiperazine and 1-(2-hydroxyethyl)piperazine afforded the title compounds Ib, Ic and IIa. The corresponding 2-alkyl-7-fluorodibenzo[b,f]thiepins VIIa-c were obtained as by-products. Reaction of the ketone IVc with 1-methylpiperazine in the presence of titanium tetrachloride gave the enamine VIII. The piperazine derivatives prepared are very potent neuroleptic agents with regard to their acute activities. Important prolongation of the effects was found mainly with the isopropyl compounds Ic and VIII.

Potential psychotropic and antihistamine agents: 1- and 3-alkyl-9-(3-dimethylaminopropylidene)-thioxanthenes and 3-alkyl-11-piperazino-10,11-dihydrodibenzo[b,f]thiepins

1982 ◽  
Vol 47 (11) ◽  
pp. 3134-3147 ◽  
Author(s):  
Miroslav Protiva ◽  
Zdeněk Šedivý ◽  
Jiří Holubek ◽  
Emil Svátek ◽  
Jiřina Metyšová ◽  
...  
Keyword(s):  
Potassium Hydroxide ◽  
Polyphosphoric Acid ◽  
Substitution Reactions ◽  
Tertiary Alcohols ◽  
Alkyl Derivatives ◽  
Antitussive Effect ◽  
Antihistamine Activity ◽  
Acid Catalyzed ◽  
High Doses ◽  
The Individual

Reactions of 3-methylthiophenol and 3-ethylthiophenol with 2-iodobenzoic acid and (2-iodophenyl)acetic acid in the presence of potassium hydroxide and copper gave the acids IVab and Xab. The acids IVab afforded by cyclization with sulfuric acid mixtures of 1- and 3-alkylthioxanthones (Va + VIa, Vb + VIb) which were separated by crystallization or chromatography and the individual compounds were identified by spectra. The slightly prevailing 3-alkyl derivatives Vab were reacted with 3-dimethylaminopropylmagnesium chloride to give the tertiary alcohols VIIab which were transformed by the acid catalyzed dehydration to the title compounds Iab. 1-Ethylthioxanthone (VIb) afforded similarly via the tertiary alcohol VIII the title compound IX. The acids Xab were cyclized with polyphosphoric acid unequivocally to the ketones XIab which were converted via the alcohols XIIab to the chloro derivatives XIIIab. Substitution reactions with 1-methylpiperazine and 1-(2-hydroxyethyl)piperazine led to the title compounds IIab and IIIb. The compounds prepared (I-III) have antihistamine activity and are more or less central depressant. Compounds Ib, IIb and IIIb revealed a clear cataleptic activity and compound Ib showed also antireserpine activity. Compound IX is centrally depressant only in high doses but it has anticonvulsant effects and a significant antitussive effect.

Towards Enantioselective Electrophilic Trifluoromethylation of β-Keto Esters

2006 ◽  
Author(s):  
Dominique Cahard ◽  
Jun-An Ma ◽  
Vitaliy Petrik
Keyword(s):  
Keto Esters

Estimate of Hyperconjugation Strength in Alkylaromatics and Unsaturated Hydrocarbons Derived from Refractometric Data

2020 ◽  
Vol 23 (23) ◽  
pp. 2598-2613
Author(s):  
Boris A. Zaitsev
Keyword(s):  
Quantitative Estimation ◽  
Physical Phenomenon ◽  
Unsaturated Hydrocarbons ◽  
Resonance Effects ◽  
Alkyl Derivatives ◽  
Retrospective View ◽  
Scientific Papers ◽  
Polycyclic Aromatic ◽  
Qualitative Measure ◽  
Steric Inhibition Of Resonance

: A retrospective view of exaltation of refraction observed for many unsaturated and aromatic compounds demonstrates that this physical phenomenon is undeservedly considered only as a qualitative measure of conjugation. This mini-review discusses numerous papers by the author that have been published earlier in inaccessible periodicals and collections of scientific papers. Using a great number of illustrations, the author shows that this parameter can be successfully used for quantitative estimate of resonance effects in organic and polymer chemistry. The methods for derivation of strictly additive atomic and group refraction constants are described; these constants were subsequently used as a tool that allowed quantitative estimation of resonance effects in mono-, di-, tri- and polyalkylbenzenes, alkylnaphthalenes, some alkyl derivatives of unsaturated hydrocarbons. These effects cause strictly fixed increase in refraction of carbon atoms in different structural modifications (graphene, fullerene, diamond) and in polycyclic aromatic hydrocarbons. The relevant results regarding quantitative estimation of degree of steric inhibition of resonance in sterically hindered ortho-dialkylbenzenes, 1,2,3- trialkyl-, 1,2,3,4-tetraalkyl-, and 1,2,3,4,5-polyalkylbenzenes accumulated by the author are summarized.

Synthesis and Biological Evaluation of Scutellarein Alkyl Derivatives as Preventing Neurodegenerative Agents with Improved Lipid Soluble Properties

2019 ◽  
Vol 15 (7) ◽  
pp. 771-780
Author(s):  
He-Min Li ◽  
Ting Gu ◽  
Wen-Yu Wu ◽  
Shao-Peng Yu ◽  
Tian-Yuan Fan ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Neuronal Damage ◽  
Thiobarbituric Acid ◽  
Rat Hepatocytes ◽  
Biological Evaluation ◽  
Thiobarbituric Acid Reactive Substance ◽  
Alkyl Derivatives ◽  
Promising Therapeutic Approach ◽  
Microsomal Membranes

Background: Exogenous antioxidants are considered as a promising therapeutic approach to treat neurodegenerative diseases since they could prevent and/or minimize the neuronal damage by oxidation. Objective: Three series of lipophilic compounds structurally based on scutellarein (2), which is one metabolite of scutellarin (1) in vivo, have been designed and synthesized. Methods: Their antioxidant activity was evaluated by detecting the 2-thiobarbituric acid reactive substance (TBARS) produced in the ferrous salt/ascorbate-induced autoxidation of lipids, which were present in microsomal membranes of rat hepatocytes. The lipophilicity of these compounds indicated as partition coefficient between n-octanol and buffer was investigated by ultraviolet (UV) spectrophotometer. Results: This study indicated that compound 5e which had a benzyl group substituted at the C4'- OH position showed a potent antioxidant activity and good lipophilicity. Conclusion: 5e could be an effective candidate for preventing or reducing the oxidative status associated with the neurodegenerative processes.

Diastereoselective Reduction of Selected α-substituted β-keto Esters and the Assignment of the Relative Configuration by 1H-NMR Spectroscopy

2020 ◽  
Vol 07 ◽  
Author(s):  
Christian Trapp ◽  
Corinna Schuster ◽  
Chris Drewniok ◽  
Dieter Greif ◽  
Martin Hofrichter
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr ◽  
1H Nmr Spectroscopy ◽  
Selective Reduction ◽  
Reducing Agents ◽  
Relative Configuration ◽  
Curtius Rearrangement ◽  
Keto Esters ◽  
Hydroxy Esters ◽  
Diastereoselective Reduction

Background:: Chiral β-hydroxy esters and α-substituted β-hydroxy esters represent versatile building blocks for pheromones, β-lactam antibiotics and 1,2- or 1,3-aminoalcohols. Objective:: Synthesis of versatile α-substituted β-keto esters and their diastereoselective reduction to the corresponding syn- or anti-α-substituted β-hydroxy esters. Assignment of the relative configuration by NMR-spectroscopy after a CURTIUS rearrangement of α-substituted β-keto esters to 4-substituted 5-methyloxazolidin-2-ones. Method:: Diastereoselective reduction was achieved by using different LEWIS acids (zinc, titanium and cerium) in combination with complex borohydrides as reducing agents. Assignment of the relative configuration was verified by 1H-NMR spectroscopy after CURTIUS-rearrangement of α-substituted β-hydroxy esters to 4-substituted 5-methyloxazolidin-2-ones. Results:: For the syn-selective reduction, titanium tetrachloride (TiCl4) in combination with a pyridine-borane complex (py BH3) led to diastereoselectivities up to 99% dr. High anti-selective reduction was achieved by using cerium trichloride (CeCl3) and steric hindered reducing agents such as lithium triethylborohydride (LiEt3BH). After CURTIUS-rearrangement of each α-substituted β-hydroxy ester to the corresponding 4-substituted 5-methyloxazolidin-2-one, the relative configuration was confirmed by 1H NMR-spectroscopy. Conclusion:: We have expanded the procedure of LEWIS acid-mediated diastereoselective reduction to bulky α-substituents such as the isopropyl group and the electron withdrawing phenyl ring.

Fluorinated tricyclic neuroleptics with prolonged action: 8-Methoxy, 8-ethoxy, 8-ethylthio and 8-hydroxy derivatives of 3-fluoro-10-(4-methylpiperazino)-10,11-dihydrodibenzo[b,f]thiepin

1982 ◽  
Vol 47 (5) ◽  
pp. 1382-1391 ◽  
Author(s):  
Jiří Jílek ◽  
Josef Pomykáček ◽  
Jiřina Metyšová ◽  
Miroslav Protiva
Keyword(s):  
Acetic Acid ◽  
Polyphosphoric Acid ◽  
Prolonged Action ◽  
Substitution Reactions ◽  
Methoxy Derivative ◽  
Chloro Derivatives ◽  
Boron Tribromide ◽  
Derivatives Of ◽  
Central Depressant ◽  
Boiling Toluene

Acids IIa-c were prepared by reactions of (4-fluoro-2-iodophenyl)acetic acid with 4-methoxythiophenol, 4-ethoxythiophenol and 4-(ethylthio)thiophenol and cyclized with polyphosphoric acid in boiling toluene to dibenzo[b,f]thiepin-10(11H)-ones IIIa-c. Reduction with sodium borohydride afforded the alcohols IVa-c which were treated with hydrogen chloride and gave the chloro derivatives Va-c. Substitution reactions with 1-methylpiperazine resulted in the title compounds Ia-c out of which the methoxy derivative Ia was transformed by demethylation with boron tribromide to the phenol Id. Compounds Ia-d are very potent neuroleptics exhibiting a clear prolongation of the central depressant and some prolongation of the cataleptic activity.

7-O-Alkyl derivatives of daunomycinone

1984 ◽  
Vol 49 (1) ◽  
pp. 313-319 ◽  
Author(s):  
Věra Přikrylová ◽  
Petr Sedmera ◽  
Josef V. Jizba ◽  
Jindřich Vokoun ◽  
Helena Lipavská ◽  
...  
Keyword(s):  
H Nmr ◽  
Toluenesulfonic Acid ◽  
Alkyl Derivatives ◽  
Derivatives Of

Reaction of daunomycinone (I) with alcohols and p-toluenesulfonic acid produces a mixture (~3 : 1) of its (7S)- and (7R)-O-alkyl derivatives II-IX. According to the 1H NMR evidence, the alicyclic ring exists in the 9H8 conformation in (7R)-O-alkyl derivatives, on the contrary to (7S)-epimers and 7-epi-daunomycinone that adopt the 8H9 conformation.

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