2,4,6-Tris(4-iodophenoxy)-1,3,5-triazine as a new recyclable “iodoarene” for in situ generation of hypervalent iodine(III) reagent for α-tosyloxylation of enolizable ketones

The synthesis of 2,4,6-tris[(4-iodo)phenoxy)]-1,3,5-triazine 6, as a new recyclable nonpolymeric analogue of iodobenzene is achieved using the reaction of 2,4,6-trichloro-1,3,5-triazine with 4-iodophenol in the presence of KOH. The application of 6 as a recyclable ‘iodoarene’ is demonstrated for α-tosyloxylation of enolizable ketones via in situ generation of hypervalent iodine(III) species using PTSA and MCPBA as the terminal oxidant. The recyclability of the reagent 6 was possible owing to the facile recovery and reuse from the reaction mixture due to its near insolubility in methanol.     

Selective reactivity of diamino Fischer-type carbene complexes towards 2,6-disubstituted and 2,4,6-trisubstituted pyrylium salts and 2,4,6-trichloro-1,3,5-triazine

The synthesis of new amino Fischer-type carbene complexes 2a-d with amino-containing side chain is presented. The reaction of these complexes with 2,4,6-triarylpyrylium salts gave the corresponding pyridinium salt 4a, 4c-e as expected from the initial attack of the free amino group onto the pyrylium α-carbon. When using the 2,6-diphenylpyrylium salt, a γ-addition of the amino group occurred, leading - after an hydrogen migration and a ring opening step - to the new organometallic unsaturated aminoketone 5. Finally, the reactivity of the diaminocarbene 2b with 2,4,6-trichloro-1,3,5-triazine has been investigated. The new triazine 6 bearing a ferrocenylaminocarbene group was isolated.     

Tautomerism, structure and properties of 1,1′,1″-(2,4,6-trihydroxybenzene-1,3,5-triyl)triethanone

According to computational predictions 1,1′,1″-(2,4,6-trihydroxybenzene-1,3,5-triyl)triethanone (triacetylphloroglucinol) (TTT, form a) can exist in five tautomeric forms, among which 2,4,6-tris(1-hydroxyethylidene)-1,3,5-cyclohexanetrione (form e) exhibits thermodynamic stability comparable to that of form a. X-ray investigations reveal that the compound exists in form a in the crystalline solid phase. Analysis of the arrangement of atoms involved in the three intramolecular H-bonds, responsible for the stabilization of tautomer a by 55.4 kcal/mol, suggests that there could be fast H atom (proton) transfer within the hydrogen bonds, bringing about the transformation of a into e and vice versa. Such an effect could explain the unique behaviour and spectral properties of TTT in solutions.     

Synthesis of novel indole based cyclophanes and cylindrical cyclophanes by tandem alkylation methodology using NaH

Treatment of 1 equiv of 1,3-bis(bromomethyl)benzene and 2,6-bis(bromomethyl)pyridine with 1 equiv of indole in the presence of NaH in THF afforded the symmetrical cyclophanes 1 and 2. Using similar methodology, cylindrical cyclophanes 3 and 4 were obtained from 2 equiv of 1,3,5-trimethyl-2,4,6-tris(bromomethyl)benzene and 1,3,5-tris(bromomethyl)benzene with 3 equiv of indole.     

Design and synthesis of organochalcogen (Se or Te) based multifunctional derivatives: structural determination and dynamic behavior of 2-chloro-4,6-bis(phenylselenoethylamino)-1,3,5-triazines

A novel class of multifunctional and multinucleate chalcogen (selenium and tellurium) containing derivatives (1-10) has been developed based on sequential chloride substitution of 2,4,6-trichloro-1,3,5-triazine with chalcogen-bearing amines. The structure of compound 1 has been determined in the solid state by X-ray crystallography.     

The case of a Cd2Cu2 complex containing an apparently C3-symmetric ligand: Erroneous ligand-structure assignment by X-ray diffraction data analysis

A simplified synthesis of a previously reported Cd₂Cu₂ complex 4 was developed in order to have a more readily available source of 1,3,5-tris(trifluoromethyl)-cyclohexane-cis,cis-1,3,5-triol 1, a unique tridentate ligand, only tentatively identified elsewhere. Attempts to liberate the ligand from 4 resulted in the sole formation of 2,4,6-tris(trifluoromethyl)-tetrahydropyran-cis,cis-2,4,6-triol (2); no traces of 1 were detected. A newly conducted X-ray analysis of complex 4 led to diffraction data that could be explained either by the previously reported structure for 4 or by the statistically disordered structure 5, containing ligand 2 rather than 1. Whereas refinement of both models led to equivalent merit factors, mass spectral data and elemental analysis of the crystals revealed unequivocally the sole presence of the tetrahydropyran derivative within the complex and proved thus the erroneous structure assignment 4 previously published for compound 5.     

Preparation of 5-amino-6-oxo-1,6-dihydro[1,2,4]triazine-3-carboxylic acid derivatives and synthesis of compound libraries thereof

Treatment of [1,3,5]triazine-2,4,6-tricarboxylic acid triethyl ester (4) with arylhydrazines provided 5-amino-6-oxo-1,6-dihydro[1,2,4]triazine-3-carboxylic acid ethyl esters 5a-g in moderate to good yields. Hydrolysis under basic conditions gave the corresponding free carboxylic acids 6a-d. Despite the relatively high number of heteroatoms present the amido as-triazine compounds 6a-d showed good solubility in phosphate buffer as determined by a lyophilization solubility assay. Building block 5a served as starting point for the syntheses of two discrete exocyclic 5-amido and 3-amido compound libraries 7 and 8, respectively.     

Synthesis,crystal structures and magnetic behaviors of two dicyanamide bridged di- and polynuclear complexes of cobalt(II) derived from 2,4,6-tris(2-pyridyl)1,3,5-triazine and imidazole

Two new dicyanamido-bridged di- and polynuclear complexes of Co(II), [Co(dca)(tptz)(H₂O)]₂·2(ClO₄) (1) and [Co(dca)₂(imz)₂]_n (2) [dca, dicyanamide; tptz, 2,4,6-tris(2-pyridyl)1,3,5-triazine; and imz, imidazole] have been synthesized and characterized structurally, as well as magnetically. The X-ray single crystal structure determination of complex 1 shows that two symmetry related octahedral Co(II) ions are separated by dca ligand and other coordination sites are satisfied by tptz and aquo ligands. Each dinuclear unit is associated with each other by intramolecular hydrogen bonding interactions, giving rise to a 1D chain structure. On the other hand complex 2 is a 1D coordination polymer having [Co(II)(imz)₂] units connected by double bridging dca ligands. These 1D chains interact through face-to-face π–π stacking interactions of the imz rings extending the dimensionality to a 2D supramolecular network. The variable temperature (300–2 K) magnetic measurements of both compounds reveal that dicyanamide exhibits a weak antiferromagnetic interaction between the metal centers.     

Liquid crystals in the series of 2,4,6-tristyryl-1,3,5-triazines

Alkaline condensation reactions of 2,4,6-trimethyl-1,3,5-triazine (1) and substituted benzaldehydes (2a-n) yield 2,4,6-tristyryl-1,3,5-triazines (3a-n). A sufficient number and length of the alkoxy chains at the benzene rings provide liquid crystalline phases Col_hd. A special structure was found for compound 3i with 9 hexyloxy chains; it exists in the solid state in a helical columnar arrangement, which is transformed by heating to a hexagonal columnar mesophase. Irradiation of the mesophases of 3i-3m leads to partial cyclodimerization reactions, which cause different textures and lower the clearing points. The border line between the irradiated and the unirradiated zones is preserved in the solid and the liquid crystalline temperature range but also over a surprisingly long period in the molten state. A detailed study of this imaging technique was performed for the LC phase of 3i.     

The structure of 2,4,6-tris(1<Emphasis Type="Italic">H</Emphasis>–pyrazol-1-yl)-1,3,5-triazine in the solid state: on polymorphs,pseudopolymorphs and co-crystals

Three structures of 2,4,6-tris(1H–pyrazol-1-yl)-1,3,5-triazine (TPT) have been determined at 193 K: the isolated molecule (2a), a solvate containing molecules of water and acetonitrile (2b) and a complex of two molecules of TPT and three molecules of water (2c). To discuss the structures, B3LYP/6–311++G(d,p) calculations have been carried out, in particular, in what concerns hydrogen bonds.     

Cyanuric and thiocyanuric esters as carriers of boron-containing fragments and their fragmentation in mass spectrometry

Tripropargylic esters 2 and 10 of cyanuric and thiocyanuric acids were synthesized. Interaction of these compounds with disubstituted amines gives monoaminoderivatives of dipropargyloxy-s-triazine 4 and 11. Diaminosubstituted propargyloxy-s-triazine 6 was prepared from the corresponding diaminochloroderivative 5. First examples of boron-containing s-triazines 7, 8, 12, 13 were prepared by reaction of propargyl esters 4, 6, 10, 11 with decaborane. New rearrangements of the molecular ions of the 2-aminoderivatives of 4,6-dipropargyloxy-1,3,5-triazine in mass spectrometry were found.     

Reactions of 1,3,5-tris(fluorosulfonyl)benzene with some nucleophilic reagents

The reactions of 1,3,5-tris(fluorosulfonyl)benzene 1 with nucleophilic agents were investigated. It was found that morpholine, β,β,β-trifluoroethanol in the presence of triethylamine and sodium azide formed corresponding 1,3,5-trisulfonyl derivatives. In contrast, nucleophiles such as aniline, thiourea, and potassium thiocyanate do not react with compound 1 even in excess and under moderate heating. The conditions for the selective fluorine atom substitution in one SO₂F group with morpholine, DMAP and aniline in the presence of triethylamine as well as in two SO₂F groups with DMAP were found. Anionic σ-complex of compound 1 with nitromethane was isolated as individual compound.     

Discotic liquid crystalline materials for potential nonlinear optical applications: synthesis and liquid crystalline behavior of 1,3,5-triphenyl-2,4,6-triazine derivatives containing achiral and chiral alkyl chains at the periphery

As a novel approach to nonlinear optical materials, new octupolar discotic liquid crystalline materials 1,3,5-triphenyl-2,4,6-triazine derivatives containing achiral alkyl chains (5a) and chiral alkyl chains (5b) at the periphery were synthesized. The former exhibits an ordered hexagonal columnar mesophase, whereas the latter displays a rectangular columnar mesophase. The negative exciton splitting observed in the CD spectrum of a thin film of 5b suggests that it has a left-handed helical structure within the column.     

Syntheses,characterizations and crystal structures of monomeric or macrocyclic compounds of di- or triorganotin (IV) moieties with 4,4′-thiodibenzenethiol

Six organotin compounds with 4,4′-thiodibenzenethiol (LH₂) of the type R_nSnL_4−nSnR_n (n = 3: R = Me 1, Ph 2, PhCH₂3, n = 2: R = Me 4, Ph 5, PhCH₂6) have been synthesized. All compounds were characterized by elemental analysis, IR and NMR (¹H, ¹³C, and ¹¹⁹Sn) spectra. The structures of compounds 1, 2, 4, 5 and 6 were also determined by X-ray diffraction analysis, which revealed that compounds 1 and 2 were monomeric structures, compounds 4, 5 and 6 were centrosymmetric dinuclear macrocyclic structures, and all the tin(IV) atoms are four-coordinated. Furthermore, supramolecular structures were also found in compounds 1, 2, 4, 5 and 6, which exhibit one-dimensional chains, two-dimensional networks or three-dimensional structures through intermolecular C–H?S weak hydrogen bonds (WHBs), non-bonded Sn?S interactions or C–H?π interactions.     

Thermodynamic stability of 2,4,6-tris(nitromethyl)-1,3,5-triazine: an experimental and theoretical study

The molecular geometries and electronic structures of 2,4,6-tris(nitromethyl)-1,3,5-triazine isomers were investigated by the density functional method DFT/B3LYP/6-311++G** to elucidate the structural factors responsible for the stability of these systems. It was shown that a characteristic feature of the nitromethyl tautomer (1) of 2,4,6-tris (nitromethyl)-1,3,5-triazine consists in nonvalence interactions between an oxygen atom of nitro group and a carbon atom of triazine ring, which are probably due to Coulomb attraction between them. The tautomer with the 2,4,6-tris (nitromethylene)-hexahyrdo-1,3,5-triazine structure (2) is stabilized trough direct polar conjugation between the amino and nitro groups at the double bond. Structural strain of the molecule with the 2,4,6-tris(aci-nitromethyl)-1,3,5-triazine structure (3) is the reason for its thermodynamic instability. X-ray data indicate that the compound under study exists in the triazine tautomeric form 1 and the distances between oxygen atoms of nitro group and carbon atom of the triazine ring are shortened. NMR data suggest the existence of triazine in the nitromethyl form 1 in acetonitrile and acetone and a tautomeric equilibrium between the nitromethyl and nitromethylene forms in a more polar solvent (DMSO). The results obtained suggest a Coulomb-type stabilization of the 2,4,6-tris(nitromethyl)-1,3,5-triazine molecule in the gas phase, in the crystal, and in nonpolar solvents.     

Synthesis and characterization of polar functional group substituted mono- and bis-(o-carboranyl)-1,3,5-triazine derivatives

Synthesis, structural characterization, and biological activity studies of o-carborane-substituted 1,3,5-triazines (9-12) containing polar functional groups such as methoxyethyl and t-butoxycarbonylmethyl amine units are described. De-methylation of di(methoxyethyl)amine functionalized triazines 9 and 10 resulted in the production of di(hydroxyethyl)amine derivatives 13 and 14. NMR (¹H and ¹³C) and X-ray crystallographic studies confirmed the structures derived from the sequential o-carborane substitution on the 1,3,5-triazine core. Preliminary in vitro studies revealed that compounds 9, 10, 13, and 14, despite their low cytotoxicity, accumulated at high levels in B-16 melanoma cells.     

Anion-controlled networks of intermolecular interactions in the crystal structure of 9-aminoacridinium salts

A series of salts, with the 9-aminoacridinium cation (9-AA) and aromatic carboxylic acid: benzoate (1), ortho-phthalate (2), and salicylate (3) anions have been synthesized and characterized using X-ray diffraction. In the crystal packing, the ions are linked via N-H?O, O-H?O, and C-H?O hydrogen bonds. Analysis of the hydrogen bonds in the crystal lattices of the title compounds shows that the cations and anions form tetramers. The ions in these tetramers are linked via N(amino)-H?O(carboxy) hydrogen bonds forming R₂²(8) (1 and 3) or R₂⁴(15) (2) hydrogen bond ring motifs. The cations interact through π-π interactions in the ABBA (1), AB (2) or ABA (3) arrangement to form columns (1 and 2) or chains (3).     

A tandem decarboxylation and inverse electron-demand Diels-Alder reaction of amino-thiophenecarboxylic acids with 1,3,5-triazines

The scope of 1,3,5-triazine inverse electron-demand Diels-Alder (IDA) reactions was expanded to include aminothiophenecarboxylic acids as latent dienophiles. A series of 2-amino-3-thiophenecarboxylic acids (1a-d) and a 3-amino-2-thiophenecarboxylic acid (5) were introduced as productive dienophiles in IDA reactions with various 1,3,5-triazines (2a-e). This method is useful for the one-step synthesis of both thieno[2,3-d]pyrimidines and thieno[3,2-d]pyrimidines, which should complement existing methods.     

Star-shaped conjugated compounds forming nematic discotic systems

Star-shaped compounds, having a benzene (9a,b) or a 1,3,5-triazine (11a,b) core and stilbenoid arms were prepared. Hexyloxy chains, attached in the middle of the arms, provide nematic discotic phases N_D, which are unusual for such systems. The position of the sidechains prevents the micro-segregation, which is valid for star-shaped discs of columnar phases. The stilbenoid character of 9a,b and 11a,b guarantees a high light sensitivity. Apart from the statistical CC bond formation by irradiation in solution or in the LC phases, a topochemically controlled chemo-, regio- and stereoselective photocyclodimerization 11a→12 was found in the crystalline state. The structure determination of 12 is based on different two-dimensional NMR techniques (COSY, NOESY, HMQC, HMBC).