RESUMEN
Thienylallylamines, readily accessible from the corresponding thienyl aldehydes, react with maleic and trifluoromethylmaleic anhydrides leading to the formation of acids with a thieno[2,3-f]isoindole core. The reaction sequence involves two successive steps: acylation of the nitrogen atom of the initial allylamine and the intramolecular Diels-Alder vinylarene (IMDAV) reaction. The scope and limitations of the proposed method were thoroughly investigated. It has been revealed with the aid of X-ray analysis and DFT calculations that the key step, the IMDAV reaction, proceeds through an exo-transition state, giving rise to the exclusive formation of a single diastereomer of the target heterocycle. The obtained functionally substituted thieno[2,3-f]isoindole carboxylic acids are potentially useful substrates for further transformations and bioscreening. The antimicrobial evaluation of the obtained compounds revealed that 1-oxo-2-(3-(trifluoromethyl)phenyl)hexahydrobenzo[4,5]thieno[2,3-f]isoindole-10-carboxylic acid is the most active sample in the synthesized library. It exhibits antibacterial activity against sensitive strains of Gram-positive bacteria, including S. aureus, Enterococcus faecium, Bacillus cereus, and Micrococcus luteus, as well as the Gram-negative bacteria E. coli and Pseudomonas fluorescens, with MIC values ranging from 4 to 64 µg mL-1. 9-Oxo-8-phenyloctahydronaphtho[2,1-d]thieno[2,3-f]isoindole-10-carboxylic acid showed antifungal activity against yeast culture C. albicans with a MIC value of 32 µM.
Asunto(s)
Escherichia coli , Staphylococcus aureus , Pruebas de Sensibilidad Microbiana , Antibacterianos/química , Ácidos Carboxílicos , IsoindolesRESUMEN
One-pot synthesis of tetrahydro-ß-carbolines, fused with an isoindole core, was proposed starting from maleic anhydride and azomethines easily available from tryptamines and 3-(hetaryl)acroleins. This sequence includes four key steps: an acylation of the aldimine with maleic anhydride, a Pictet-Spengler cyclization, an intramolecular Diels-Alder reaction, and a concluding [1,3]-H shift. As a result, six- or seven-nuclear alkaloid-like heterocyclic systems, containing a benzo[1,2]indolizino[8,7-b]indole fragment annulated with furan, thiophene, or pyrrole, are formed in a diastereoselective manner.
RESUMEN
Diversely substituted, partially saturated benzo[f]isoindole-4-carboxylic acids were synthesized by a new three-component reaction (3CR) starting from cinnamic amines (3-arylallylamines), maleimides, and maleic anhydride. The process consists of N-acylation of the amines by maleic anhydride, intramolecular [4 + 2] cycloaddition in vinylarenes (the IMDAV reaction), and the concluding Alder-ene reaction between Diels-Alder intermediates and maleimides. All of the reaction steps proceed in a highly regio- and stereoselective manner, furnishing five adjacent chiral centers and leading to a single diastereoisomer of the title compound. The efficiency of the transformation is secured by thermal conditions or utilization of soft Lewis acids (Yb(OTf)3) as catalysts. The kinetics and mechanism of the 3CR were studied by using dynamic 19F NMR. Based on the NMR data and density functional theory (DFT) calculations, the IMDAV, not the Alder-ene, reaction is the rate-limiting step of the entire process.
RESUMEN
The title compound, C15H15Br2NO2, crystallizes with two mol-ecules in the asymmetric unit of the unit cell. In both mol-ecules, the tetra-hydro-furan rings adopt an envelope conformation with the O atom as the flap and the pyrrolidine rings adopt an envelope conformation. In the crystal, mol-ecules are linked by weak C-Hâ¯O hydrogen bonds, forming sheets lying parallel to the (002) plane. These sheets are connected only by weak van der Waals inter-actions. The most important contributions to the surface contacts are from Hâ¯H (44.6%), Brâ¯H/Hâ¯Br (24.1%), Oâ¯H/Hâ¯O (13.5%) and Câ¯H/Hâ¯C (11.2%) inter-actions, as concluded from a Hirshfeld surface analysis.
RESUMEN
In the title compound, C20H19NO5, the central six-membered ring has a slightly distorted half-chair conformation, with puckering parameters of Q T = 0.3387â (11)â Å, θ = 49.11â (19)° and φ = 167.3â (2)°. The conformation of the fused pyrrolidine ring is that of an envelope. Mol-ecules are connected by inter-molecular C-Hâ¯O hydrogen bonds, C-Hâ¯π inter-actions and π-π stacking inter-actions [centroid-to-centroid distance = 3.9536â (11)â Å, with a slippage of 2.047â Å], forming a three-dimensional network. The most important contributions to the surface contacts are from Hâ¯H (46.3%), Oâ¯H/Hâ¯O (31.5%) and Câ¯H/Hâ¯C (17.3%) inter-actions, as concluded from a Hirshfeld surface analysis.
RESUMEN
N-t-Bu-N',N''-Disulfonamide-1,3,5-triazinanes were synthesized and characterized by X-ray single crystal structure analysis. In the course of the X-ray structure elucidation, the first solid experimental evidence of the axial position of the tert-butyl group in unconstrained hexahydro-1,3,5-triazacyclohexanes was obtained. Dynamic low-temperature NMR analysis allowed to fully investigate a rare case of crystallization-driven unanchoring of the tert-butyl group in the chair conformation of saturated six-membered cycles. DFT calculations show that the use of explicit solvent molecules is necessary to explain the equatorial position of the t-Bu group in solution. Otherwise, the axial conformer is the thermodynamically stable isomer.
RESUMEN
Compounds (I), C22H20N2O2, (II), C22H20N2O2 and (III), C20H18N2O3 are the products of three-component reactions between isatoic anhydride, the corresponding amine and 3-(5-methylfuran-2-yl)- or (furan-2-yl)-2-methyl-acryl-aldehyde. Compound (I) crystallizes in the monoclinic space group P21/n, while compounds (II) and (III) are isostructural and crystallize in the ortho-rhom-bic space group Pbca. The tetra-hydro-pyrimidine ring in (I)-(III) adopts a sofa conformation. The NH nitro-gen atom has a trigonal-pyramidal geometry, whereas the N(R) nitro-gen atom is flattened. The furyl-vinyl substituents in (I)-(III) are practically planar and have an E configuration at the C=C double bond. In (I), this bulky fragment occupies the axial position at the quaternary carbon atom of the tetra-hydro-pyrimidine ring, whereas in (II) and (III) it is equatorially disposed. In the crystal of (I), mol-ecules form hydrogen-bonded chains propagating along [001] by strong inter-molecular N-Hâ¯O hydrogen bonds. The chains are packed in stacks along the a-axis direction. In the crystals of (II) and (III), mol-ecules also form hydrogen-bonded chains propagating along [100] by strong inter-molecular N-Hâ¯O hydrogen bonds. However, despite the fact that compounds (II) and (III) are isostructural, steric differences between the phenyl and furyl substituents result in chains with different geometries. Thus in the crystal of (II) the chains have a zigzag-like structure, whereas in the crystal of (III), they are almost linear. In both (II) and (III), the hydrogen-bonded chains are further packed in stacks along the b-axis direction.
RESUMEN
The chiral title compounds, C21H18N2O2, (I), and C21H18N2OS, (II) - products of the three-component reaction between benzyl-amine, isatoic anhydride and furyl- or thienyl-acrolein - are isostructural and form isomorphous racemic crystals. The tetra-hydro-pyrimidine ring in (I) and (II) adopts a sofa conformation. The amino N atom has a trigonal-pyramidal geometry [sum of the bond angles is 347.0° for both (I) and (II)], whereas the amido N atom is flat [sum of the bond angles is 359.3° for both (I) and (II)]. The furyl- and thienylethenyl substituents in (I) and (II) are planar and the conformation about the bridging C=C bond is E. These bulky fragments occupy the axial position at the quaternary C atom of the tetra-hydro-pyrimidine ring, apparently, due to steric reasons. In the crystals, mol-ecules of (I) and (II) form hydrogen-bonded helicoidal chains propagating along [010] by strong inter-molecular N-Hâ¯O hydrogen bonds.
RESUMEN
The tandem [4+2] cycloaddition between hexafluoro-2-butyne and bis-furyl dienes, like difurfuryl ester, at room temperature leads to the kinetically controlled "pincer"-adducts - annulated 4a,8a-bis(trifluoromethyl)hexahydro-1,4:5,8-diepoxynaphthalenes. On the other hand, if these reactions proceed at 140 °C, only the thermodynamically controlled "domino"-adducts - annulated 2,3-bis(trifluoromethyl)hexahydro-1,4:5,8-diepoxynaphthalenes - are formed. Therefore, a very rare and unexpected example of full kinetic and thermodynamic control in the Diels-Alder reaction is reported in this paper.
RESUMEN
The title mol-ecular salts, C15H20NO+·C4H3O4-, (I), and C9H15INO+·C4H3O4-, (II), have very similar mol-ecular geometries for both cation and anion. The anions of both (I) and (II) are practically planar (r.m.s. deviations = 0.062 and 0.072â Å, respectively) and adopt a rare symmetrical geometry with the hy-droxy H atom approximately equidistant from the two O atoms. In their crystals, the cations and anions in both (I) and (II) form tight ionic pairs via strong N-Hâ¯O hydrogen bonds, with a roughly perpendicular disposition of the anion to the furan ring of the cation. This ion-pair conformation appears to correlate with the lack of reactivity of these salts in [4 + 2] cyclo-addition reactions. In the extended structures of (I) and (II), the ion pairs form hydrogen-bonded chains propagating along [010] and [001], respectively, via N-Hâ¯O hydrogen bonds.
RESUMEN
The title compound, C21H18N2O4, obtained as a racemate, contains a novel heterocyclic system, viz. isoindolo[1,2-c]pyrrolo-[1,2-a][1,4]benzodiazepine. The central diazepane ring has a distorted boat conformation with two phenyl-ene-fused and one methine C atom deviating by 0.931â (1), 0.887â (1) and 0.561â (1)â Å, respectively, from the mean plane of the rest of the ring. The γ-lactone ring has an envelope conformation, with the C atom opposite to amide bond deviating by 0.355â (1)â Å from its plane. In the crystal, mol-ecules form centrosymmetric dimers through pairs of C-Hâ¯O hydrogen bonds.
RESUMEN
The title molecule, C20H23NO7, the product of nucleophilic cleavage of the 3a,6-ep-oxy bridge in 1-oxo-2-phenyl-octa-hydro-3a,6-ep-oxy-iso-indole-7-carboxyl-ate, comprises a cis-fused bicyclic system containing a 2-pyrrolidinone ring in an envelope conformation (with the C atom bearing the carboxyl-ate substituent as the flap) and a cyclo-hexane ring in a chair conformation. The carboxyl-ate substituent occupies the equatorial position, whereas the two acet-yloxy substituents are in axial positions. The N atom has a trigonal-planar geometry, the sum of the bond angles being 359.3â (3)°. The dihedral angle between the mean plane of the four planar atoms of the pyrrolidinone ring and the phenyl ring is 25.98â (6)°. In the crystal, mol-ecules are linked into zigzag chains along the c-axis direction by C-Hâ¯O hydrogen bonds.
RESUMEN
A number of C-3 spirocyclic 2-benzazepine analogs of α-phenyl-N-tert-butyl nitrone (PBN) were synthesized and tested for their activity in protecting rat brain mitochondria and dopaminergic (DA) neurons against 6-hydroxydopamine (6-OHDA), a toxin inducing destruction of the DA nigro-striatal pathway in rodent models of Parkinson's disease. The newly synthesized nitrone derivatives were firstly investigated for their activity in decreasing the level of hydroxyl radicals generated during 6-OHDA oxidation, and inhibit lipid peroxidation (TBARS assay) and protein carbonyl content (PCC) in rat brain mitochondria. Most of the studied 2-benzazepine nitrones showed inhibitory potencies in both TBARS and PCC assays at least two magnitude orders higher than that of PBN. The data obtained usefully complemented the known structure-activity relationships. In particular, 5 and 10, bearing C-3 spiro cyclopentyl and tetrahydropyranyl moieties, respectively, at 8 µM concentration proved to be significantly more effective than PBN in protecting cultured DA neurons exposed to 6-OHDA, which alone causes about 45% cell loss in 24 h. In addition, we found that 5 inhibited butyrylcholinesterase with an IC(50) value of 16.8 µM, which would enhance its potential as neuroprotective agent in Alzheimer's neurodegeneration. These findings extend the utility of benzazepine-based PBN analogs in the treatment of age-related free radical-mediated disorders.
Asunto(s)
Benzazepinas/farmacología , Encéfalo/efectos de los fármacos , Neuronas Dopaminérgicas/efectos de los fármacos , Fármacos Neuroprotectores/farmacología , Óxidos de Nitrógeno/farmacología , Estrés Oxidativo/efectos de los fármacos , Animales , Benzazepinas/química , Encéfalo/metabolismo , Encéfalo/patología , Recuento de Células , Células Cultivadas , Inhibidores de la Colinesterasa/farmacología , Óxidos N-Cíclicos/farmacología , Modelos Animales de Enfermedad , Neuronas Dopaminérgicas/metabolismo , Neuronas Dopaminérgicas/patología , Concentración 50 Inhibidora , Peroxidación de Lípido/efectos de los fármacos , Mitocondrias/metabolismo , Estructura Molecular , Fármacos Neuroprotectores/química , Óxidos de Nitrógeno/química , Oxidopamina , Enfermedad de Parkinson Secundaria/inducido químicamente , Enfermedad de Parkinson Secundaria/tratamiento farmacológico , Enfermedad de Parkinson Secundaria/metabolismo , Enfermedad de Parkinson Secundaria/patología , Cultivo Primario de Células , Carbonilación Proteica/efectos de los fármacos , Relación Estructura-ActividadRESUMEN
The title compound, C(23)H(18)N(2)O(6), is the product of an intra-molecular thermal cyclo-addition within 1-malein-2-[(E)-2-(2-fur-yl)vin-yl]-4-oxo-3,4-dihydro-quinazoline. The mol-ecule comprises a previously unknown fused penta-cyclic system containing two five-membered rings (2-pyrrolidinone and furan) and three six-membered rings (benzene, 2,3-dihydro-4-pyrimidinone and dihydro-cyclo-hexa-ne). The central five-membered pyrrolidinone ring has the usual envelope conformation. The six-membered dihydro-pyrimidinone and dihydro-cyclo-hexane rings adopt a half-boat and a half-chair conformation, respectively. The dihedral angle between the planes of the terminal benzene and furan rings is 45.99â (7)°. In the crystal, O-Hâ¯O hydrogen bonds link the mol-ecules into centrosymmetric dimers. Weak C-Hâ¯O hydrogen bonds consolidate further the crystal packing, which exhibits π-π inter-actions, with a short distance of 3.556â (3)â Å between the centroids of benzene rings of neighbouring mol-ecules.
RESUMEN
The title compound, the product of an acid-catalysed Wagner-Meerwein skeletal rearrangement, crystallizes as an ethanol monosolvate, C(20)H(21)NO(8)·C(2)H(6)O. The title mol-ecule comprises a fused tricyclic system containing two five-membered rings (cyclo-pentane and tetra-hydro-furan) in the usual envelope conformations and one six-membered ring (piperidinone) adopting a flattened twist-boat conformation.
RESUMEN
The title compound, C(26)H(28)N(2)O(9)·1.5H(2)O, the product of an acid-catalysed Wagner-Meerwein skeletal rearrangement, crystallizes as a sesquihydrate with the O atom of one of the two independent water mol-ecules occupying a special position on a twofold axis. The organic mol-ecule comprises a fused penta-cyclic system containing two five-membered rings (cyclo-pentane and tetra-hydro-furan) and three six-membered rings (piperidinone, tetra-hydro-pyridine and benzene). The five-membered rings have the usual envelope conformations, and the central six-membered piperidinone and tetra-hydro-pyridine rings adopt boat and sofa conformations, respectively. In the crystal, there are three independent O-Hâ¯O hydrogen bonds, which link the organic mol-ecules and water mol-ecules into complex two-tier layers parallel to (001). The layers are further linked into a three-dimensional framework by attractive inter-molecular carbon-yl-carbonyl inter-actions.
