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Gevorkyan, A. A.; Arakelyan, A. S.; Petrosyan, K. A.; Margaryan, A. Kh.

doi:10.1023/a:1012305301604

Cited by 2 publications

(2 citation statements)

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“…The extracts were washed with water and dried over sodium sulfate, the solvent was removed, and the residue was distilled under reduced pressure, a fraction boiling in the temperature range from 160 to 175°C (3 mm) being collected (about 16 g). Repeated fractional distillation of that fraction gave 11.1 g (88.9%) of a product with bp 168175°C (3 mm) which, according to the 1 H NMR data, was a mixture of 3-bis(ethoxycarbonyl)methyl-and 3-bis(butoxycarbonyl)methyl-4-methyl-3,6-dihydro-2H-pyrans IIIa and IIIb at a ratio of 16 …”

Section: Methodsmentioning

confidence: 99%

“…In addition, it is believed that heterolytic dissociation of a Cnucleofuge bond is a three-rather than two-step process, each step corresponding to one type of ion pairs. These types include contact, loose, and solventseparated ion pairs (IP c , IP l , and IP ss ), the two latter possessing electrophilic properties [16]. Each type of ion pairs is characterized by specific regio-and stereochemical transformations, regardless of the type of chemical bond and transformation mode.…”

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confidence: 99%

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Alkylation of 3,4-Dibromo-4-methyltetrahydropyran with Diethyl Malonate as a Key to Understanding the Electronic Nature of Chemo- and Regioselectivity of Molecules

et al. 2005

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The reaction of 3,4-dibromo-4-methyltetrahydropyran with diethyl malonate in the presence of sodium butoxide leads to formation of the corresponding cross-coupling product rather than of tetraethyl ethane-1,1,2,2-tetracarboxylate (product of dehydrodimerization of diethyl malonate) which is formed in the presence of sodium ethoxide. An explanation was proposed, which may be regarded as a key to understanding the nature of the driving force for one-and two-electron transfer, as well as chemo-and regioselectivity of organic molecules.It was recently shown that the dehydrobromination substitution pattern (Scheme 1, path 1: I g II g III), which is typical of reactions of 3,4-dibromo-4-methyltetrahydropyran (I) with a series of nucleophiles (such as amines, phenols, alcohols, organic acid salts, etc.) [13], is not followed in reactions with enolates derived from b-dicarbonyl compounds [4]. In the latter case, dehydrodimers IV of b-dicarbonyl compounds (path 2) and dihydropyran V are formed instead of cross-coupling products III. It may seem that we revealed just one more example of radical nucleophilic substitution whose general relations have long been known [510].However, it becomes clear that this fact also contains important information on both driving forces of radical nucleophilic substitution itself and chemo-and regiochemistry of molecules on the whole [1113]. This information can be revealed by considering the problem in terms of the ion-pair version of mechanisms of organic reactions, which distinctly differentiates the roles of reagent and substrate [1420]. Without going into details (for more information, see [1518]), we should note that such refinement of the behavior of a reagent and a substrate rules out possible arbitrary treatment of nucleophilic or electrophilic properties of reagents [1113]. Another specific feature of the above version is that it implies the charge on an atom in a reagent, estimated in the chemical bond ionic character units, as a measure of the ability of a Cnucleofuge bond to undergo heterolysis and the degree of extension of the Cnucleofuge bond in the substrate as a measure of regio-and stereochemistry [1618]. In addition, it is believed that heterolytic dissociation of a Cnucleofuge bond is a three-rather than two-step process, each step corresponding to one type of ion pairs. These types include contact, loose, and solventseparated ion pairs (IP c , IP l , and IP ss ), the two latter possessing electrophilic properties [16]. Each type of ion pairs is characterized by specific regio-and stereochemical transformations, regardless of the type of chemical bond and transformation mode.Success of the approach is achieved due to the fact that the most important source of information on the nature of the driving force of a reaction is the product structure. This belief originates from the assumption that structure of a molecule contains so much important and reliable information on the properties of its precursors (ion pairs and molecules as a whole) that cannot be obtained b...

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

Alkylation of 3,4-Dibromo-4-methyltetrahydropyran with Diethyl Malonate as a Key to Understanding the Electronic Nature of Chemo- and Regioselectivity of Molecules

et al. 2005

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Microwave-assisted regioselective synthesis of acyclic nucleosides through an alkylating reaction with 2-oxa-1,4-butanediol diacetate

Qu¹,

Han²,

Zhang³

et al. 2006

Can. J. Chem.

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An efficient and green procedure for the synthesis of purine acyclic nucleosides through microwave-assisted alkylation of various purine nucleobases with 2-oxa-1,4-butanediol diacetate in the absence of solvent and catalyst is described. The advantages of using this method include its environmental friendliness, simple manipulation, short reaction time, high regioselectivity, and good yields.Key words: acyclic nucleosides, microwave irradiation, regioselectivity, alkylation, 2-oxa-1,4-butanediol diacetate.

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Cited by 2 publications

References 23 publications

Alkylation of 3,4-Dibromo-4-methyltetrahydropyran with Diethyl Malonate as a Key to Understanding the Electronic Nature of Chemo- and Regioselectivity of Molecules

Alkylation of 3,4-Dibromo-4-methyltetrahydropyran with Diethyl Malonate as a Key to Understanding the Electronic Nature of Chemo- and Regioselectivity of Molecules

Microwave-assisted regioselective synthesis of acyclic nucleosides through an alkylating reaction with 2-oxa-1,4-butanediol diacetate

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