Azinium-N-(2′-azinyl)aminides: synthesis, structure and reactivity

Carceller, Rosa; Garcia‐Navio, J. L.; Izquierdo, M. Luisa; Alvárez‐Builla, Julio; Fajardo, Mariano; Gómez‐Sal, Pilar; Gago, Federico

doi:10.1016/s0040-4020(01)90411-9

Cited by 31 publications

(21 citation statements)

References 17 publications

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“…Table 2. Dihedral angles (in º) of the compounds of Table 1 Molecule In their 1994 paper, 17 Alvarez-Builla et al reported the X-ray molecular structure of 1 (LESKEZ) 19 characterized by two dihedral angles, the one involving the C-N bond, θ 1 = 177.5º…”

Section: Resultsmentioning

confidence: 99%

“…All the minima are planar, including 1, in agreement with the previous result. 17 We have calculated two minima for the radicals, the N···H and the C · ···H. In the case of the sixmembered rings, the structure with an HB with the lone pair (LP) of the nitrogen atom is more stable than that with an HB to the carbon atom radical by about 11-12 kJ mol Figure 6 shows that both barriers are related and, as in the case of the neutral molecules, when one increases the other decreases, meaning that the partial double bond character of two single bonds (the N-N and the N-C) are related.…”

Section: Resultsmentioning

confidence: 99%

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Pyridinium-N-(2-pyridyl)aminides and related compounds: a theoretical study

Alkorta¹,

Elguero²

2010

Arkivoc

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Dedicated to our friend Prof. Julio Alvarez-Builla on the occasion of his 65 th anniversary AbstractSeven families of pyridinium-N-(heteroaryl)aminides, both azinyl and azolyl, have been studied. For each family, three structures have been considered, the "classical" and two radicals. The transition states corresponding to the rotation of the pyridinium and the heterocycle were calculated at the B3LYP/6-31G* level.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Pyridinium-N-(2-pyridyl)aminides and related compounds: a theoretical study

Alkorta¹,

Elguero²

2010

Arkivoc

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“…Ylides 2a,b have been previously described. 17,18 2.1. Preparation of pyridinium salts 9a -m and 14a,b…”

Section: Methodsmentioning

confidence: 99%

“…Two factors can explain the observed regioselectivity, the stabilizing effect of the pyridinium moiety over the exocyclic N-aminide anion, and the existence of an intramolecular hydrogen bond blocking the a-nuclear nitrogen. 17 The final N -N bond reduction of the pyridinium salts affords the corresponding 2-alkylaminoazines 4.…”

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confidence: 99%

Pyridinium N‐(2′‐Azinyl)aminides: Regioselective Synthesis of N‐(2‐Pyridyl) Substituted Polyamines.

et al. 2003

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Abstract-The regioselective alkylation of pyridinium-N-(2 0 -pyridyl)aminide with alkyl dihalides under mild conditions, followed by N-N bond reduction of the corresponding bis-salts, allowed an easy preparation of N,N 0 -bis(2-pyridyl)diamines. The same methodology has been applied to the synthesis of N,N 0 ,N 00 -tris(2-pyridyl)triamines. q 2002 Elsevier Science Ltd. All rights reserved.The role of polyamines in biological systems is well recognized and, over the last two decades, many functions of prokaryotic and eukaryotic cells have been shown to be polyamine dependent. 1 -3 Natural and synthetic polyamines are potent cation-channel blockers and templates for the design of synthetic vectors with potential application in gene therapy. 3 A number of polyamine analogues have shown promise as anticancer agents 4,5 and a platinum complex linked by a bridging diamine showed biological activity against various human cancer cell lines. 6,7 The synthetic approaches to polyamine chemistry have been recently reviewed, being the N-alkylation of amines the most widely used reaction in polyamine synthesis. 8 To avoid polyalkylation, excess of amine or a suitable protecting group have to be used but, in the field of diamines and polyamines, mono N-alkylation has been achieved using cesium hydroxide. 9 In the last years, we have been interested in heteroaryl-stabilized cycloiminium ylides 1, as building blocks for the synthesis of heterocyclic derivatives 10 -15 and, more recently, we are exploring the synthetic utility of pyridinium N-(2 0 -azinyl)aminides 2 (Scheme 1). 16 -21 Some of our work in this field has been concerned with alkylation processes and in a preceding 21 paper we reported the regioselective synthesis of 2-alkylaminoazines 4 in a two-step method. As it is well known, the direct alkylation of heterocyclic amidines 5 is unsatisfactory as a preparative method, because mixtures of N-endosubstituted 6 and N-exosubstituted 7 derivatives are obtained and, usually, alkylation mainly occurs at the most basic endocyclic nitrogen 22,23 (Scheme 1). However, when permanent nitride species, such as the pyridinium N-(2 0 azinyl)aminides 2, are used, regioselective alkylation takes place at the exocyclic nitrogen, and the salts 3

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“…4 -6 Moreover, N-alkylation process takes place regioselectively over the aminide nitrogen, by the partial blockage of the heteroaryl a-nitrogen, via an intramolecular hydrogen bond. 4 The N -N bond reduction of the resulting pyridinium salts should allow the preparation of the corresponding amines 4,7 or polyamines. 8 When N-alkylation was performed with a-haloesters or a-haloketones, pyrido[1,2-a]pyrimidin-4-ones and imidazo[1,2-a]pyridines were respectively obtained by a cascade heterocyclisation process.…”

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confidence: 99%