Thiopyran Ring Research Articles

A Deep-Red Emissive Sulfur-Doped Double [7]Helicene Photosensitizer: Synthesis, Structure and Chiral Optical Properties.

Doping of polycyclic conjugated hydrocarbons (PCHs) with sulfur atoms is becoming more and more important as a means of creating unique functional materials. Recently, thiophene-containing multiple helicenes have garnered enormous attention due to their intriguing electronic and (chir)optical properties compared with carbohelicenes. However, the efficient synthesis of thiopyran-containing multiple helicenes and the underlying sulfur doping mechanisms are rather unexplored. Herein, the synthesis and structural analysis of a thiopyran-containing double [7]helicene 3 are reported. X-ray crystallographic analysis reveals 3 and its dication with C2-symmetric propeller-shape structure and compact p-p interaction in the solid state. 3 exhibits deep-red to near-infrared (NIR) fluorescence emission. Tunable aromaticity of the central benzene ring and thiopyran rings is found by chemical oxidation, which is further confirmed by nucleus-independent chemical shift (NICS), anisotropy of the induced current density (AICD) and harmonic oscillator model of aromaticity (HOMA) analysis. Furthermore, the chiral and photosensitizing characters of 3 are investigated. The excellent deep-red to NIR fluorescence, circularly polarized luminescence (CPL) and photosensitizing activities suggest that 3 can be used as an outstanding photosensitizer in photodynamic therapy (PDT) and bioimaging, especially paving the way for future CPL-PDT and CPL-bio-probe applications.

Thiopyran-Fused Mono and Double Helicenes with Low Band Gaps via Simultaneous Ring Expansion and 6-endo Cyclizations.

Mono and double helicenes (M5, M6, D5, and D6) containing six-membered thiopyran rings have been successfully prepared via simultaneous ring expansion and 6-endo cycloisomerizations from the corresponding precursors with five-membered thiophene rings. Although D5 and D6 exhibit similar chemical structures, they demonstrate completely different helical structures because of their distinct steric clashes caused by the incorporated methyl groups. Moreover, all of the thiopyran-fused helicenes exhibit broad absorption bands covering the visible and near-infrared regions.

C-H arylation of thiopyran derivatives with aryl halides.

A C-H arylation of thiopyran derivatives with aryl halides has been developed. Under the catalysis of Pd(OAc)2/Ag2CO3, the C-H arylation takes place at the α-position of the thiopyran ring. When dibromo-substituted compounds are used as reactants, double C-H arylations may occur on the same thiopyran ring at its α- and β-positions.

Domino reactions of thiopyrano[4,3-b]indole-3(5H)-thiones and dimethyl acetylenedicarboxylate: Quantum chemical investigation and experiment

Reaction of thiopyrano[4,3-b]indole-3(5H)-thiones and dimethyl acetylenedicarboxylate (DMAD) proceeds via two competing cascade pathways. Initially, both the pathways begin from thiocarbonyl sulfur and acetylene carbon atoms interaction. Then two parallel processes take place: an alkyne–thiocarbonyl metathesis and a (3 + 2) cycloaddition. In the next stages, in both cases, thiophene ring formation and thiopyran ring opening proceed. Finally, (4 + 2) cycloaddition reactions of intermediate thioketones and a second equivalent of DMAD leads to the resulting thiopyrano[4,3-b]indole derivatives bearing thienyl substituent. The kinetic and thermodynamic characteristics of both pathways were compared on the basis of DFT and ab initio 6-311++G(d,p) quantum chemical calculations.

Xylaridines C and D, Unusual Thiopyranodipyridine Alkaloids from the Fungus Xylaria longipes.

Structurally unique thiopyranodipyridine alkaloids xylaridines C (1) and D (2) were isolated from the fungus Xylaria longipes. Their structures were established by comprehensive spectroscopic analysis combined with single-crystal X-ray diffraction and electron-capture detection (ECD) calculations. Compound 1 possesses two piperidine moieties fused with a centered thiopyran ring, while compound 2 is a dimer of 1. Compound 1 was resoluted into optical pure enatiomers (+)-1 and (-)-1 by chiral HPLC. Moreover, compound 2 was resoluted into an optically pure compound (+)-2 and a mixture of (-)-2 and meso-2. Plausible biosynthetic pathways of compounds 1 and 2 are proposed.

Synthesis and antimicrobial evaluation of some new bicyclopyrazolone‐based thiopyran ring systems

A series of bicyclopyrazolones were synthesized from the condensation reaction of methyl 4‐oxotetrahydro‐2H‐thiopyran‐3‐carboxylate with hydrazine derivatives in ethanol. All synthesized products were characterized by FT‐IR, 1H, and 13C NMR spectral data, elemental analyses, and mass spectrometry. The antibacterial and antifungal activities of these compounds were evaluated against Staphylococcus aureus and Bacillus subtilis as Gram‐positive bacteria, Escherichia coli and Pseudomonas aeruginosa as Gram‐negative bacteria, and the fungus Candida albicans. The results revealed that bicyclopyrazolones including an aryl or aryl sulfonyl group in the N‐2 position of the pyrazolone moiety are the most effective against all the microorganisms studied in this work.

Synthesis and Neurotropic Activity of 4-Phenylpyridine-3-Carboxylic Acid and 3-Hydroxy-4-Phenylthieno[2,3-b]-Pyridine Derivatives

Aseries of pyridine-3-carboxylic acid derivatives were synthesized via recyclization of a thiopyran ring using cyclic secondary amines and then converted into substituted thieno[2,3-b]pyridines. Studies of the neurotropic properties identified several synthesized compounds with anticonvulsant activity against corazole-induced seizures. The compounds were active as psychological sedatives and, in contrast with the tranquilizer diazepam, were inactive as central myorelaxants at anticonvulsant doses.

Crystal structure of methyl 7-phenyl-6a,7,7a,8,9,10-hexa-hydro-6H,11aH-thio-chromeno[3,4-b]pyrrolizine-6a--carbox-ylate.

In the title compound, C22H23NO2S, the inner pyrrolidine ring (A) adopts an envelope conformation with the methine C atom opposite the fused C—N bond as the flap. The thio­pyran ring (C) has a half-chair conformation and its mean plane is inclined to the fused benzene ring by 1.74 (11)°, and by 60.52 (11)° to the mean plane of pyrrolidine ring A. In the outer pyrrolidine ring (B), the C atom opposite the fused C—N bond is disordered [site-occupancy ratio = 0.427 (13):0.573 (13)] and both rings have envelope conformations, with the disordered C atom as the flap. The planes of the phenyl ring and the benzene ring of the thio­chromane unit are inclined to one another by 65.52 (14)°. In the crystal, mol­ecules are linked by a pair of C—H⋯O hydrogen bonds forming inversion dimers.

Crystal structure of methyl 3-(3-fluoro-phen-yl)-1-methyl-1,3a,4,9b-tetra-hydro-3H-thio-chromeno[4,3-c]isoxazole-3a-carboxyl-ate.

In the title compound, C19H18FNO3S, the five-membered oxazolidine ring adopts an envelope conformation with the methine C atom of the fused bond as the flap. Its mean plane is oriented at a dihedral angle of 50.38 (1)° with respect to the fluoro­phenyl ring. The six-membered thio­pyran ring has a half-chair conformation and its mean plane is almost coplanar with the fused benzene ring, making a dihedral angle of 4.94 (10)°. The two aromatic rings are inclined to one another by 85.96 (11)°, and the mean planes of the oxazolidine and thio­pyran rings are inclined to one another by 57.64 (12)°. In the crystal, mol­ecules are linked by C—H⋯π inter­actions, forming a three-dimensional structure.

Crystal structures of methyl 3-(4-iso-propyl-phen-yl)-1-methyl-1,2,3,3a,4,9b-hexa-hydro-thio-chromeno[4,3-b]pyrrole-3a-carboxyl-ate, methyl 1-methyl-3-(o-tol-yl)-1,2,3,3a,4,9b-hexa-hydro-thio-chromeno[4,3-b]pyrrole-3a-carboxyl-ate and methyl 1-methyl-3-(o-tol-yl)-3,3a,4,9b-tetra-hydro-1H-thio-chromeno[4,3-c]isoxazole-3a-carboxyl-ate.

In the title compounds, C23H27NO2S, (I), and C21H23NO2S, (II), the pyrrole rings have envelope conformations with the C atom substituted by the benzene ring as the flap. In the third title compound, C20H21NO3S, (III), the isoxazole ring has a twisted conformation on the C-C bond substituted by the benzene ring and the carboxyl-ate group. In all three compounds, the thio-pyran ring has a half-chair conformation. The mean plane of the pyrrole ring is inclined to the mean plane of the thio-pyran ring by 57.07 (9), 58.98 (9) and 60.34 (12)° in (I), (II) and (III), respectively. The benzene rings are inclined to one another by 73.26 (10)° in (I), 65.781)° in (II) and 63.37 (13)° in (III). In the crystals of all three compounds, there are no classical hydrogen bonds present. Only in the crystal of compound (I) are mol-ecules linked by a pair of C-H⋯π inter-actions, forming inversion dimers. The isopropyl group in compound (I) is disordered over two sets of sites and has a refined occupancy ratio of 0.586 (13):0.414 (13).

Flupentixol tartrate

In the title salt, C23H26F3N2OS+·C4H5O6 − [systematic name: 1-(2-hy­droxy­eth­yl)-4-[3-(2-(tri­fluoro­meth­yl)thioxanthen-9-yl­idene)prop­yl]piperazin-1-ium 3-carb­oxy-2,3-di­hydroxy­pro­pion­ate], the monoprotonated piperazine ring in the cation adopts a chair conformation, while the thio­pyran ring of the thioxanthene group has a boat conformation. The dihedral angle between the mean planes of the two outer aromatic rings of the thioxanthene groups is 31.6 (2)°. In the crystal, the cations and anions are linked via O—H⋯O, N—H⋯O, O—H⋯N and C—H⋯O hydrogen bonds, forming chains propagating along [100]. In addition, R 2 2(7), R 2 2(11), R 2 2(10) and R 2 2(12) graph-set ring motifs involving the anions, and R 2 2(9) graph-set ring motifs involving both the cations and anions are observed. The three F atoms of the tri­fluoro­methyl group are disordered over two sets of sites and the individual atoms were refined with occupancy ratios of 0.54 (6):0.46 (6), 0.72 (2):0.28 (2) and 0.67 (3):0.33 (3).

Facile construction of densely functionalized thiopyrano[2,3-b]quinolines via three-component reactions catalyzed by l-proline

L-Proline catalyzed, three-component reactions of 2-mercaptoquinoline-3-carbaldehyde, malononitrile and thiol-based nucleophiles were developed for the first time, for the synthesis of various 4H-substituted thiopyrano[2,3-b]quinolines derivatives via a Knoevenagel condensation followed by inter-intramolecular double Michael addition reaction. This transformation leads to the generation of a 4-substituted thiopyran ring, together with one C–C and two C–S bonds in a single operation.

Rac-2,2′-(Thiane-2,6-diyl)bis[1-(4-bromophenyl)ethanone

In the title compound, C21H20Br2O2S, prepared by the reaction of 1,9-bis­(4-bromo­phen­yl)nona-2,7-diene-1,9-dione with sodium sulfide nona­hydrate in acetonitrile, the six-membered thio­pyran ring has a chair conformation while the H atoms ortho to the S atom adopt a cis configuration. The dihedral angle between the two benzene rings is 2.59 (8)°.

New thiopyran-4-spiro-2′-(1,3-dithiolane): Formation mechanism and crystal structure

Abstract Ethylene trithiocarbonate reacted with dimethyl acetylenedicarboxylate to furnish tetramethyl thiopyran-4-spiro-2′-(1,3-dithiolane)-2,3,5,6-tetracarboxylate, a new thiopyran-4-spiro-2′-(1,3-dithiolane) heterocyclic compound, as the minor product together with the major product dimethyl 2-thioxo-1,3-dithiole-4,5-dicarboxylate. The new heterocycle was probably formed through a [2 + 2] cycloaddition between ethylene trithiocarbonate and dimethyl acetylenedicarboxylate followed by a 1,3-dipolar cycloaddition or [4 + 2] cycloaddition. Crystal structure of the new compound revealed that the thiopyran ring and 1,3-dithiolane moiety were perpendicular to each other.

3-Phenyl-2-(pyrrolidin-1-yl)-5,6-dihydro-8H-thiopyrano[4′,3′:4,5]thieno[2,3-d]pyrimidin-4(3H)-one

In the title compound, C19H19N3OS2, the thio­pyran ring adopts a twist-chair conformation and the pyrimidinone unit is essentially planar, with a mean deviation of 0.0497 Å. The thio­phene ring is essentially planar with a maximum deviation of 0.024 (2) Å, while the pyrrolidine ring exhibits an envelope conformation. The pyrimidinone and thio­phene rings are almost coplanar, forming a dihedral angle of 6.31 (15)°, while the dihedral angle between the mean planes of the phenyl ring and the pyrimidinone ring is 68.13 (10)°. In the crystal structure, adjacent mol­ecules are linked by C—H⋯O hydrogen bonds, forming a two-dimensional network in the ac plane.

Enantioselctive Syntheses of Sulfur Analogues of Flavan-3-Ols

The first enantioselective syntheses of sulfur flavan-3-ol analogues 1–8 have been accomplished, whereby the oxygen atom of the pyran ring has been replaced by a sulfur atom. The key steps were: (a) Pd(0) catalyzed introduction of –S t-butyl group, (b) Sharpless enantioselective dihydroxylation of the alkene, (c) acid catalyzed ring closure to produce the thiopyran ring, and (d) removal of benzyl groups using N,N-dimethylaniline and AlCl3. The compounds were isolated in high chemical and optical purity.

A novel approach towards the synthesis of tricyclic systems based on pyridine, pyran, thiopyran, azepine, oxepin, thiepin, and pyrimidine rings under different solvent conditions

Synthesis of some oxygen, nitrogen, and sulfur based condensed heterocycles by the condensation of dimedone with aromatic monoaldehyde under different solvent conditions has been achieved.

Ring‐Opening/Ring‐Closing Protocols from Nitrothiophenes: Six‐Membered versus Unusual Eight‐Membered Sulfur Heterocycles through Michael‐Type Addition on Nitrobutadienes

When Ar is a low-aromaticity homo- or heterosystem, the sulfonyl-stabilized anion of nitrobutadienes 4 (which derive from the initial ring opening of 3-nitrothiophene) undergoes a rather surprising addition onto the aromatic ring itself, thereby leading to the construction of an unusual eight-membered sulfur heterocycle condensed with the original Ar ring. The competitiveness of such a pathway with respect to the formation of the thiopyran ring (i.e., addition onto the nitrovinyl moiety) is favored at low temperatures, thus revealing its nature as a kinetically controlled process.

Synthesis, crystal structure, and physical property of radical cation salt of 2-(thiopyran-4-ylidene)-4,5-ethylenedithio-1,3-dithiole (TP-EDTT): (TP-EDTT) 2SbF 6

Electrocrystallization of 2-(thiopyran-4-ylidene)-4,5-ethylenedithio-1,3-dithiole (TP-EDTT) in an electrolytic solution containing tetrabutylammonium hexafluoroantimonate afforded black elongated platelets of (TP-EDTT) 2SbF 6. (TP-EDTT) 2SbF 6 crystallized in a triclinic system with space group P 1 ¯ : a=6.496(2), b=7.197(3), c=15.294(4) Å, α=95.58(3), β=102.09(2), γ=101.41(2)°, V=678.1(4) Å 3, Z=1, and R=0.035 ( I≥2 σ( I)). One TP-EDTT molecule and one half SbF 6 anion were crystallographically unique. TP-EDTT molecules formed a dimerized one-dimensional stacking column along the b-axis with a head-to-tail manner. Short S⋯S contacts were observed between ethylenedithio-1,3-dithiole moieties of adjacent molecules along the molecular short axis, and short S⋯F and H⋯F contacts were also observed between the thiopyran ring of TP-EDTT molecule and SbF 6 anion along the molecular long axis. Tight-binding band calculation afforded the effective half-filled band structure due to the strong dimerization. The electrical resistivity showed semiconductive temperature dependence from room temperature ( σ RT=6.1×10 −1 S cm −1, E a=92 meV). Raman spectroscopy revealed no sign of charge disproportionation in the range from 300 to 6 K. (TP-EDTT) 2SbF 6 is considered to be a dimer Mott insulator.

6-Amino-8-(2-bromophenyl)-1,7,8,8a-tetrahydro-3H-isothiochromene-5,7,7-tricarbonitrile dimethylformamide solvate

In the title compound, C18H13BrN4S·C3H7NO, the thio­pyran ring and the adjacent six-numbered ring adopt distorted boat conformations. The mol­ecules, lying about inversion centers, form hydrogen-bonded dimers involving one of the H atoms on the amino group with the N atom of a cyano group of an adjacent mol­ecule, resulting in a 12-membered ring system [R 2 2(12) ring motif]. The other H atom of the amino group forms an inter­molecular hydrogen bond with the O atom of the dimethyl­formamide (DMF) mol­ecule. Another lone pair of electrons on the same carbonyl O atom of DMF mol­ecule forms a non-classical C—H⋯O inter­molecular hydrogen bond, resulting in a chain of mol­ecules.