Reactions of adamantanes in electrophilic media

Моисеев, И. К.; Макарова, Н. В.; Земцова, М. Н.

doi:10.1070/rc1999v068n12abeh000495

Cited by 45 publications

(34 citation statements)

References 107 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…À is believed [58] to be responsible for the CÀH activation. We first modeled this reaction computationally for the complex of NO 2 + with one molecule of HNO 3 ).…”

Section: Nomentioning

confidence: 98%

Functionalized Nanodiamonds Part I. An Experimental Assessment of Diamantane and Computational Predictions for Higher Diamondoids

Fokin

Tkachenko

Gunchenko

et al. 2005

Chemistry A European J

120

150

View full text Add to dashboard Cite

The structures, strain energies, and enthalpies of formation of diamantane 1, triamantane 2, isomeric tetramantanes 3-5, T(d)-pentamantane 6, and D(3d)-hexamantane 7, and the structures of their respective radicals, cations, as well as radical cations, were computed at the B3LYP/6-31G* level of theory. For the most symmetrical hydrocarbons, the relative strain (per carbon atom) decreases from the lower to the higher diamondoids. The relative stabilities of isomeric diamondoidyl radicals vary only within small limits, while the stabilities of the diamondoidyl cations increase with cage size and depend strongly on the geometric position of the charge. Positive charge located close to the geometrical center of the molecule is stabilized by 2-5 kcal mol(-1). In contrast, diamondoid radical cations preferentially form highly delocalized structures with elongated peripheral C-H bonds. The effective spin/charge delocalization lowers the ionization potentials of diamondoids significantly (down to 176.9 kcal mol(-1) for 7). The reactivity of 1 was extensively studied experimentally. Whereas reactions with carbon-centered radicals (Hal)(3)C(*) (Hal=halogen) lead to mixtures of all possible tertiary and secondary halodiamantanes, uncharged electrophiles (dimethyldioxirane, m-chloroperbenzoic acid, and CrO(2)Cl(2)) give much higher tertiary versus secondary selectivities. Medial bridgehead substitution dominates in the reactions with strong electrophiles (Br(2), 100 % HNO(3)), whereas with strong single-electron transfer (SET) acceptors (photoexcited 1,2,4,5-tetracyanobenzene) apical C(4)-H bridgehead substitution is preferred. For diamondoids that form well-defined radical cations (such as 1 and 4-7), exceptionally high selectivities are expected upon oxidation with outer-sphere SET reagents.

show abstract

“…À is believed [58] to be responsible for the CÀH activation. We first modeled this reaction computationally for the complex of NO 2 + with one molecule of HNO 3 ).…”

Section: Nomentioning

confidence: 98%

Functionalized Nanodiamonds Part I. An Experimental Assessment of Diamantane and Computational Predictions for Higher Diamondoids

Fokin

Tkachenko

Gunchenko

et al. 2005

Chemistry A European J

120

150

View full text Add to dashboard Cite

show abstract

“…Different procedures are known to perform these transformations the most popular of which are halogenation, hydroxylation, carboxylation, radical alkylation and arylations with Friedel-Crafts-type chemistry. [20] The unique structure of adamantane leads to a significant degree of selectivity in these reactions for radical and cationic intermediates. Selectivity is therefore often not a problem and protocols, for example, for the selective introduction of one, two, three or four bromine atoms at the adamantane bridgeheads are well known and give all four different adamantyl bromides in good yields.…”

Section: Resultsmentioning

confidence: 99%

Rigid C₃‐Symmetric Scaffolds Based on Adamantane

Pannier¹,

Maison²

2008

Eur J Org Chem

View full text Add to dashboard Cite

Efficient syntheses of rigid C3‐symmetric scaffolds based on adamantane are described. The scaffolds are available in multigram quantities and have been designed for conjugation to various natural products such as carbohydrates and peptides. They are thus valuable for the construction of strictly defined molecular architectures with threefoldgeometry for applications in bioorganic chemistry, catalysis or material science. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

show abstract

“…The interaction of 1 bromoadamantane with benzene in the presence of the Lewis acids, depending on the reagent ratios, proceeds as benzene adamantylation with the insertion of up to three 1 Ad groups or as adamantane phenylation (insertion of several Ph substitu ents into AdH). 36 The reaction of toluene with 1 bromo adamantane afforded a mixture of the para and meta substituted products: 4 and 3 (1 adamantyl)toluenes in different contents, and no 2 (1 adamantyl)toluene (ortho substituted product) was detected even as traces. 104 No 1 (1 adamantyl)naphthalene (D) was observed in the products (A, В, C) of naphthalene alkylation by 1 ada mantanol or 1 bromoadamantane in the CCl 4 -Lewis acid (ZnCl 2 , FeCl 3 ) medium.…”

Section: Reactions Of Arene Alkylationmentioning

confidence: 98%

“…32- 36 In addition, it is used as a model substrate in the mild selective activation and functionalization of C-H bonds caused by the electrophilic, radical, photochemi cal, and biotechnological effects and the presence of cata lytic systems (polyoxometallates, metalloporphyrins, modified Gif systems (oxidation with hydrogen peroxide pyridine in the presence of metal salts, additive of an organic acid), and others). 37- 39 The stability, high sym metry, rigidity, and large volume of an AdH molecule determine specific features of the kinetics and mechanism of the reactions involving this molecule.…”

Section: Introductionmentioning

confidence: 99%

First steps of the reactions of alkanes and arenes with adamantyl cations in sulfuric acid in comparison with other reagents

Rudakov

Volkova

2008

Russ Chem Bull

View full text Add to dashboard Cite

Solutions of 1 adamantanol in sulfuric acid at T < 100 °С interact with alkanes (RH, [H 2 SO 4 ] > 85%) and arenes (ArH, [H 2 SO 4 ] > 59%). The data on the kinetics, kinetic isotope effect (KIE), effects of the structure of RH and ArH and acidity of the medium, and the observation of 1,4 cis dimethylcyclohexane isomerization indicate that adamanyl cations (Ad + ) serve as reactive species. In the reactions with alkanes, the Ad + cation abstracts the hydride ion from RH in the rate determining step. Compensation dependences appear between the activa tion parameters for the KIE and "effect 5/6" (ratio of the rate constants for the С-Н bond cleavage in cyclopentane and cyclohexane) in the reactions of cycloalkanes with Ad + and other electrophilic reagents, such as "anthracene" (An 2 )H + and hydroxymethyl (CH 2 OH) + cations and Hg II ions, including the points of the lower selectivity limit (k H /k D ) = 1.4, ("5/6") = 1. In the reactions with the Ad + cation, the bond selectivity 3 0 : 2 0 of alkanes is higher, while 2 0 : 2 0 is lower compared to other reagents. In the first case, the selectivity is probably deter mined predominantly by the energies of the cleaved С-Н bonds, whereas in the second case it is determined by steric hindrances. Judging by the kinetic and selectivity data in the series benzene-toluene-o xylene-m xylene and the absence of the reaction with p xylene, mesity lene, and pseudocumene, it can be concluded that the main contribution to the Ad + + ArH interaction is made by adamantylation to the para and meta positions of the benzene ring, whereas the ortho positions are inaccessible to the attack because of steric hindrances.

show abstract

Reactions of adamantanes in electrophilic media

Cited by 45 publications

References 107 publications

Functionalized Nanodiamonds Part I. An Experimental Assessment of Diamantane and Computational Predictions for Higher Diamondoids

Functionalized Nanodiamonds Part I. An Experimental Assessment of Diamantane and Computational Predictions for Higher Diamondoids

Rigid C₃‐Symmetric Scaffolds Based on Adamantane

First steps of the reactions of alkanes and arenes with adamantyl cations in sulfuric acid in comparison with other reagents

Contact Info

Product

Resources

About

Reactions of adamantanes in electrophilic media

Cited by 45 publications

References 107 publications

Functionalized Nanodiamonds Part I. An Experimental Assessment of Diamantane and Computational Predictions for Higher Diamondoids

Functionalized Nanodiamonds Part I. An Experimental Assessment of Diamantane and Computational Predictions for Higher Diamondoids

Rigid C3‐Symmetric Scaffolds Based on Adamantane

First steps of the reactions of alkanes and arenes with adamantyl cations in sulfuric acid in comparison with other reagents

Contact Info

Product

Resources

About

Rigid C₃‐Symmetric Scaffolds Based on Adamantane