Molecules

323 KiB

Open AccessArticle

Kinetic Support for the Generation of a Phenylsulfenium Ion Intermediate

by Hiroshi Takeuchi, Jun-ichi Tateiwa and Shintaro Moriguchi

Molecules 2003, 8(4), 392-400; https://doi.org/10.3390/80400392 - 30 Apr 2003

Cited by 1 | Viewed by 9980

In the reaction of N-methylbenzenesulfenamide (1) with thioanisole (4) in the presence of trifluoroacetic acid (TFA), the initial rate υ0 of total appearance of 2- and 4-(methylthio)phenyl phenyl sulfides (5) is first and zero order with respect to the initial concentrations of 1 and 4, respectively: υ₀=k_obs[1]₀. The pseudo-first order rate constant kobs is evaluated as 5.2×10^-4 sec^-1 with varying concentrations of 4 (0.72 to 5.0 M) in a mixture of 4 and CH₂Cl₂ in the presence of TFA at 10 °C. This data supports the notion that a phenylsulfenium ion intermediate 3 interacting with both the counter ion and the unshared electron-pair of amine is generated by heterolytic N-S scission of the protonated sulfenamide 2, leading to the observed formation of 5. Full article

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235 KiB

Open AccessReview

Synthesis and Aromatization of Hantzsch 1,4-Dihydropyridines under Microwave Irradiation. An Overview

by Jean Jacques Vanden Eynde and Annie Mayence

Molecules 2003, 8(4), 381-391; https://doi.org/10.3390/80400381 - 30 Apr 2003

Cited by 120 | Viewed by 19083

Abstract

Domestic microwave ovens as well as laboratory reactors have been successfully employed to prepare dialkyl 1,4-dihydropyridine-3,5-dicarboxylates and to induce the synthesis of the corresponding aromatic derivatives. In that latter particular case, unexpected results have been reported. Full article

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349 KiB

Open AccessArticle

PhCOCl-Py/Basic Alumina as a Versatile Reagent for Benzoylation in Solvent-Free Conditions

by Satya Paul, Puja Nanda and Rajive Gupta

Molecules 2003, 8(4), 374-380; https://doi.org/10.3390/80400374 - 30 Apr 2003

Cited by 41 | Viewed by 14663

Abstract

A solvent-free procedure using PhCOCl-Py/basic alumina under microwave irradiation has been developed for N-, O- and S-benzoylation. Full article

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290 KiB

Open AccessArticle

Synthesis of Novel 3H-Quinazolin-4-ones Containing Pyrazolinone, Pyrazole and Pyrimidinone Moieties

by Mohamed A. Saleh, Mohamed F. Abdel-Megeed, Mohamed A. Abdo and Abdel-Basset M. Shokr

Molecules 2003, 8(4), 363-373; https://doi.org/10.3390/80400363 - 30 Apr 2003

Cited by 30 | Viewed by 10978

Abstract

The diazonium salt of 3-(4-aminophenyl)-2-methyl-3H-quinazolin-4-one (2a) and its 6-bromo derivative 2b reacted with some active methylene compounds, namely ethyl acetoacetate (3), ethyl cyanoacetate (4) and acetylacetone (5), to afford the corresponding hydrazono quinazolinone derivatives 6-8. Treatment of 6a,b with hydrazine hydrate or phenyl hydrazine in refluxing ethanol afforded the corresponding pyrazolin-5-one derivatives of 3H-quinazolin-4-one 9a-d. Cyclization of 7a,b with hydrazine hydrate yielded the corresponding products 10a,b. Reaction of 8a,b with phenyl hydrazine or with urea afforded the corresponding derivatives 11a,b and 12a,b, respectively. Compounds 6-12 were identified by C,H,N analysis, IR, ¹H-NMR, ¹³C-NMR and mass spectroscopy. Full article

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174 KiB

Open AccessArticle

Solid-state Synthesis of 1-Ethoxycarbonyl-4-substituted-semicarbazides

by Shadpour Mallakpour, Abdol Reza Hajipour and Hedayat A. Taghizadeh

Molecules 2003, 8(4), 359-362; https://doi.org/10.3390/80400359 - 30 Apr 2003

Cited by 6 | Viewed by 8182

Abstract

A rapid and simple method for the preparation of 1-ethoxycarbonyl-4-substituted-semicarbazides has been developed. As examples the reaction of six different isocyanates with ethyl carbazate under solvent-free conditions are reported. Full article

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465 KiB

Open AccessOther

Signal Transduction: An Exciting Field of Investigation for Small Molecule Drug Discovery

by Serge Halazy

Molecules 2003, 8(4), 349-358; https://doi.org/10.3390/80400349 - 30 Apr 2003

Cited by 7 | Viewed by 6842

Abstract

Most protein functions associated with pathological conditions are mediated by protein conformational changes and protein-protein interactions.[...] Full article

(This article belongs to the Special Issue Selected Papers from the International Symposium on Frontiers in Molecular Science (ISFMS 2002))

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Molecules, Volume 8, Issue 4 (April 2003) – 6 articles , Pages 349-400

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