Boron-containing Analogues Research Articles

A comparative study of boron-containing and boron-omitted capsaicinoids

This study reports the synthesis and characterization of a limited number of novel boron-containing and boron-omitted capsaicinoids, providing 12 unique substrates. We have previously reported boron-containing capsaicinoids that showed improved bioactivity compared to capsaicin itself but have yet to test a series of analogous boron-omitted substrates as a direct comparison. The boron-containing capsaicinoids bear a pinacolboronate ester (Bpin) group, which was incorporated using an iridium-catalyzed hydroboration reaction. We report that although nearly all compounds display moderate cytotoxic activity that bests that of capsaicin against human colon HCT116 cancer cells, the activity of our boron-omitted capsaicinoids surpasses that of the boron-containing analogues.

In English

The regularities of interaction of hydrogen molecules with graphene-like planes, where two carbon atoms are replaced by nitrogen or boron atoms, have been studied by the methods of quantum chemistry (DFT, B3LYP, 6-31G**). To take into account the dispersion contributions to the energy of formation of intermolecular complexes that occur during the formation of adsorption supramolecular structures, Grimme’ dispersion correction is used - D3. To study the effect of the size of a graphene-like cluster on the energy of molecular hydrogen chemisorption, polyaromatic molecules (PAM) are used of pyrene, coronene and that consisting of 54 carbon atoms, as well as their nitrogen- and boron-containing analogues where N- and B-atoms are placed in a para-position relative to each other, in the so-called piperazine configuration. The insertion of a heteroatom changes the structure of the transition state and the mechanism of chemisorption. An analysis of the results of quantum chemical calculations showed the highest exothermic dissociative adsorption of the H2 molecule on B-containing graphene-like ones. For N-containing PAM, the exothermicity of the mentioned reaction is somewhat lower, for it a possibility of desorption of atomic hydrogen desorption the surface of the latter with subsequent recombination in the gas phase has been also shown. At the same time, for models of pure graphene-like layer, the data obtained indicate the impossibility of chemisorption of molecular hydrogen. Without a complete analysis of the results for all the possible locations of the pair of hydrogen atoms (formed due to dissociation of the H2 molecule) bound by nitrogen-containing polyaromatic molecules, it can be noted that the dissociative chemisorption of the H2 molecule, regardless of the nature of heteroatom in the PAM, is thermodynamically more probable at the periphery of the model molecules than that in their centers.

In Ukrainian

The features of the interaction of hydrogen molecules with graphene-like planes in which two carbon atoms are replaced by nitrogen or boron atoms are investigated by methods of quantum chemistry (DFT, B3LYP, 6-31G**). To take into account the dispersion contributions to the energy of the formation of intermolecular complexes that arise in the formation of adsorption supramolecular structures, the dispersion correction Grimme-D3 is used. To study the influence of the size of the graphene-like cluster on the molecular hydrogen chemisorption energy in the model of graphene nanoparticles, polyaromatic molecules (PAM) pyrene, coronene (Cor) and that of 54 carbon atoms, as well as their nitrogen and boron-containing analogues, in which the atoms of nitrogen and boron are placed in a para-position in relation to one another, in the so-called piperazine configuration of the atoms of nitrogen or boron. Equilibrium spatial structures of reagent molecules, formed complexes and products of dissociative chemisorption of hydrogen molecules were found by minimizing the norm of a gradient of total energy. An important stage in the transformation of physically sorbed H2 molecules on the surface of the most carbon materials is its decomposition into two hydrogen atoms that can bind to different carbon atoms of model molecules. In this case, a significant number of different reaction products of the same gross composition is formed. The lowest energy among them is related to one where the atoms of the hydrogen are bound to carbon atoms that are adjacent to the nitrogen or boron atoms. It has been found that, regardless of the size of the carbon PAM, the value of the chemisorption energy in all cases has a positive value and is greater than 100 kJ/mol. The chemisorption energy of the hydrogen molecule by PAM with heteroatoms depends on the size of the model, the position of the atoms of nitrogen and boron and, for the most part, has a small negative value (up to -35 kJ/mole), which indicates the spontaneity of the corresponding process. Calculations have shown that the lowest activation energy of the reaction of the H2 molecule with boron PAM, and the most - for pure carbon PAM, regardless of the size of the models. The nature of the heteroatom changes the structure of the transition state and the mechanism of chemisorption. Analysis of the results of quantum chemical calculations showed the highest exothermicity of dissociative adsorption of H2 molecule on boron-containing graphene-like molecules. For nitrogen-containing surfactants, the reaction is slightly less exothermic, as well as the possibility of desorption of atomic hydrogen from the surface of the latter with subsequent recombination in the gas phase. At the same time, for the models of pure graphene-like layer, these data indicate that chemosorption of molecular hydrogen is impossible. Without a total analysis of the results of all possible placements of a pair of hydrogen atoms (formed by the dissociation of the H2 molecule) when they are bound to nitrogen-containing polyaromatic molecules, it can be noted that the dissociation chemisorption of the H2 molecule, regardless of the nature of the heteroatom in the PAM, is thermodynamically more probable at the periphery of the model molecules than in their center.

Synthesis of multiple boron-containing analogs via Ugi-4CR

One of the most significant challenges in boron neutron capture therapy (BNCT) is to have an ideal boron delivery agent which can deliver sufficient numbers of boron atoms to designated tumor cells. In this work, mild synthetic conditions for synthesis of dipeptidyl multiple boron-containing analogs under microwave-assisted condition were investigated. The results showed that the reaction generally took place at 50 °C, but higher reaction temperature was required when a fluorinated building block was used. The resulting peptidyl skeletons generated by Ugi four-component reaction resemble basic cell metabolites and could potentially be used as alternative replacements for current boron carrier agents in BNCT.

Photochemical Behavior of Beryllium Complexes with Subporphyrazines and Subphthalocyanines.

Structures of beryllium subphthalocyanines and beryllium subporphyrazines complexes with different substituents are explored for the first time. Their photochemical properties are studied using time-dependent density functional theory calculations and compared to boron-related compounds for which their photochemical activity is already known. These beryllium compounds were found to be thermodynamically stable in a vacuum and present features similar to those of boron-containing analogues, although the nature of bonding between the cation and the macrocycle presents subtle differences. Most important contributions to the main peak in the Q-band region arise from HOMO to LUMO transitions in the case of subphthalocyanines and alkyl subporphyrazine complexes, whereas a mixture of that contribution and a HOMO-2 to LUMO contribution are present in the case of thioalkyl subporphyrazines. The absorption in the visible region could make these candidates suitable for photochemical devices if combined with appropriate donor groups.

Comparative Bonding Behavior of Functional Cyclopentadienyl Ligands and Boron-Containing Analogues in Heterometallic Complexes and Clusters

The reactivity of isolobal molybdenum carbonylmetalates containing a 2-boratanaphthalene, [Mo(eta5-2,4-MeC9H6BMe)(CO)3]- (5a) and [Mo(eta5-2,4-MeC9H6BNi-Pr2)(CO)3]- (5b), a 1-boratabenzene, [Mo(eta5-3,5-Me2C5H3BNi-Pr2)(CO)3]- (8), or a functionalized cyclopentadienyl ligand, the new metalate [Mo(eta5-C5H4Ph)(CO)3]- (7) and [Mo(eta5-C5H4NMe2)(CO)3]- (9), toward palladium (I and II) or platinum (I and II) complexes, such as trans-[PdCl2(NCPh)2], [Pd2(NCMe)6](BF4)2, trans-[PtCl2(PEt3)2], and [N(n-Bu)4]2 [Pt2Cl4(CO)2], has been investigated, and this has allowed an evaluation of the influence of the pi-bonded ligands on the structures and unprecedented coordination modes observed in the resulting metal-metal-bonded heterometallic clusters. The new 58 CVE planar-triangulated centrosymmetric clusters, [Mo2Pd2(eta5-C5H4Ph)2(CO)6(PEt3)2] (11), [Mo2Pd2(eta5-2,4-MeC9H6BNi-Pr2)2(CO)6] (12), [Mo(2)Pd(2)(eta5-3,5-Me2C5H3BNi-Pr2)2(CO)6] (13), [Mo2Pd2(eta5-C5H4NMe2)2(CO)6(PEt3)2] (15), [Mo2Pt2(eta5-C5H4NMe2)2(CO)6(PEt3)2] (16), and [Mo2Pt2(eta5-C5H4NMe2)2(CO)8] (20), have been characterized by single-crystal X-ray diffraction. Their structural features were compared with those of the 54 CVE cluster [Re2Pd2(eta5-C4H4BPh)2(CO)6)] (4), previously obtained from the borole-containing metalate [Re(eta5-C4H4BPh)(CO)3]- (2), in which a 2e-3c B-C(ipso)-Pd interaction involving the pi-ring was observed. As an extension of what has been observed in 4, clusters 12 and 13 present a direct interaction of the boratanaphthalene (12) and the boratabenzene (13) ligands with palladium. In clusters 11, 15, 16, and 20, the pi-ring does not interact with the palladium (11 and 15) or platinum centers (16 and 20), which confers to these clusters a geometry very similar to that of [Mo2Pd2(eta5-C5H5)2(CO)6(PEt3)2] (3b). The carbonylmetalates [Mo(pi-ring)(CO)3]- are thus best viewed as formal four electron donors which bridge a dinuclear d9-d9 unit. The orientation of this building block in the clusters influences the shape of their metal cores and the bonding mode of the bridging carbonyl ligands. The crystal structure of new centrosymmetric complex [Mo(eta5-C5H4Ph)(CO)3]2 (10) was determined, and it revealed intramolecular contacts of 2.773(4) A between the carbon atoms of carbonyl groups across the metal-metal bond and intermolecular bifurcated interactions between the carbonyl oxygen atoms (2.938(4) and 3.029(4) A), as well as intermolecular C-H...pi(Ar)(C=C) interactions (2.334(3) and 2.786(4) A) involving the phenyl substituents.

2-Aminoethoxydiphenyl Borate as a Prototype Drug for a Group of Structurally Related Calcium Channel Blockers in Human Platelets

We have synthesized a series of 2-aminoethoxydiphenyl borate (2-APB, 2,2-diphenyl-1,3,2-oxazaborolidine) analogs and tested their ability to inhibit thrombin-induced Ca(2+) influx in human platelets. The analogs were either synthesized by adding various substituents to the oxazaborolidine ring (methyl, dimethyl, tert-butyl, phenyl, methyl phenyl, and pyridyl) or increasing the size of the oxazaborolidine ring to seven- and nine-membered rings. NMR analysis of the boron-containing analogs suggests that each of them exist as a ring structure through the formation of an N-->B coordinate bond (except for the hexyl analog). The possibility that these boron-containing compounds formed dimers was also considered. All compounds dose-dependently inhibited thrombin-induced Ca(2+) influx in human platelets, with the 2,2-diphenyl-1,3,2-oxazaborolidine-5-one derivative having the weakest activity at 100 microM, whereas the (S)-4-benzyl and (R)-4-benzyl derivatives of 2-APB were approximately 10 times more potent than the parent 2-APB. Two nonboron analogs (3-methyl and 3-tert-butyl 2,2-diphenyl-1,3-oxazolidine) were synthesized; they had approximately the same activity as 2-APB, and this implies that the presence of boron was not necessary for inhibitory activity. All of the compounds tested were also able to inhibit thrombin-induced calcium release. We concluded that extensive modifications of the oxazaborolidine ring in 2-APB can be made, and Ca(2+)-blocking activity was maintained.

Chemistry and biology of some low molecular weight boron compounds for boron neutron capture therapy.

Boronated DNA targeting agents are especially attractive candidates for BNCT because they may deliver boron-10 to the nuclei of tumor cells. Numerous boron-containing analogs have been synthesized and some have shown promising results in initial biological tests. One of the most challenging tasks in this special field of research remains the finding of suitable targeting strategies for the selective delivery of boron rich DNA-intercalator/alkylator to tumor cells. Synthetic and biological studies of boron compounds suitable for DNA-binding are reviewed. The amino acid p-boronophenylalanine (BPA) is presently of considerable clinical interest. Other boronated amino acids might also be candidates for BNCT either per se, as part of part of tumor-seeking peptides or conjugated to targeting macromolecules. A large number of boronated L- and D-amino acids with varying liphophicility and sterical requirements are now available for evaluation. Recent synthetic and biological studies of aromatic boronoamino acids, carboranylamino acids and carboranyl amines are also reviewed.

MACROBICYCLIC D-METAL TRIS-DIOXIMATES OBTAINED BY CROSS-LINKING WITH P-BLOCK ELEMENTS. PART VI. PREPARATION, MOLECULAR STRUCTURE AND MÖSSBAUER (57FE, 119SN) PARAMETERS OF AN IRON(II) COMPLEX WITH A MACROBICYCLIC TIN-CONTAINING TRIS-NIOXIMATE LIGAND

Abstract The tin-containing clathrochelate complex of Fe(II) with cyclohexanedione-1,2-dioxime (nioxime, H2Nx), [FeNx3(SnCl3)2]2- · (Et2NH+ 2)2 · Et2NH2 + · Cl− · 2Pri OH was prepared by slowly adding diethylamine to a solution containing the macrobicyclic [FeNx3(SnCl3)2]2- anion. The structure of the complex has been determined by X-ray methods. Crystal data: monoclinic, space group P21/c, a = 10.565(2), b = 25.413(5), c = 20.198(4)Å, β=95.40(3)°, Z = 4. The iron atoms is encapsulated by the clathrochelate ligand and surrounded by a distorted trigonal antiprismatic coordination sphere comprising by six nitrogen atoms of three dioxime residues. The experimental value of the distortion angle (ca 37.5°) is close to that predicted by the Mössbauer (57Fe) parameters (ca 40°). The average Fe-N bond length of 1.923Å is somewhat greater than that in boron-containing analogues. The Sn atoms have a slightly distorted octahedral coordination, which also correspond to Mössbauer (119Sn) spectroscopic data. The six-membered carbocycles in the dioxime fragments have a half-chair conformation with both β-carbons displaced to the opposite sides of the mid-plane of the remaining atoms. All the active hydrogen atoms of the structure are involved in a hydrogen bond system. The possibilities of use of Mössbauer parameters and their temperature dependences to determine the geometry of iron(II) tris-dioximates and the sign of Δ in Mössbauer (57Fe) spectra are discussed.

Synthesis of rac-1-(9- o-carboranyl)nonyl-2-methyl-glycero-3-phosphocholine (B-Et-11-OMe), a potential boron carrier for Boron Neutron Capture Therapy (BNCT)

Boron-containing analogues of ether lipids are proposed as boron carriers in the boron neutron capture therapy (BNCT). The synthesis of rac-1-(9- o-Carboranyl)nonyl-2-methyl-glycero- 3-phosphocholine (B-Et-11-OMe) as a first representative is described. The carborane is introduced into the readily assembled glycerol ether moiety. The phosphocholine headgroup is introduced by 2-chloro-3-methyl-1,3,2-λ 3-oxazaphospholane using a phosphoamidite strategy and subsequent ring opening under alkylating conditions.

Structure of 4-(dimethylamino)pyridine cyanoborane adduct

C7H~oNa.BHaCN, Mr = 161.0, monoclinic, 12/a, a = 13.773 (4), b = 9.635 (3), c = 14.430 (3) ~, fl = 99.67 (2) °, V = 1888 (2) A 3, Z = 8, Dx = 1-13 gcm -3, a(Mo Ka) =0.71073/~, /z = 0.7 cm -l, F(000)=688, 294K. Final R=0.047 for 809 observed reflections. The non-hydrogen atoms in the (dimethylamino)pyridine residue are essentially co- planar; the nitrogen atom (N7) of the Me2N group has sp 2 hybridization. There is substantial localized double bonding involving N7 and the pyridine ring. The N 1--BH2CN section of the molecule has N 1--B 1.574(4), B--C 1-573(5), C--N 1-130 (4) A, N1--B---C 109.4 (3), B--C--N 178-2 (3) °. Introduction. There is considerable current interest in amine adducts of cyanoboranes as precursors to boron-containing analogues of amino acids (Spielvogel, Ahmed, Silvey, Wisian-Neilson &

Boron-Containing Analogs of Isoquinoline

<b>Boron-Containing Analogs of Isoquinoline</b>

New Heteroaromatic Compounds. XIV.1 Boron-containing Analogs of Purine, Quinazoline and Perimidine

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNew Heteroaromatic Compounds. XIV.1 Boron-containing Analogs of Purine, Quinazoline and PerimidineS. S. Chissick, M. J. S. Dewar, and P. M. MaitlisCite this: J. Am. Chem. Soc. 1961, 83, 12, 2708–2711Publication Date (Print):June 1, 1961Publication History Published online1 May 2002Published inissue 1 June 1961https://doi.org/10.1021/ja01473a025RIGHTS & PERMISSIONSArticle Views377Altmetric-Citations43LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (469 KB) Get e-Alerts Get e-Alerts