Chromene Moiety Research Articles

Application of On-line HPLC-CD Detection in Separation and Structure Elucidation of Tricyclic Cephalosporine Oxaanalogues with Chromane Moiety

Application of On-line HPLC-CD Detection in Separation and Structure Elucidation of Tricyclic Cephalosporine Oxaanalogues with Chromane Moiety

Synthesis of triphenylphosphonium vitamin E derivatives as mitochondria-targeted antioxidants

A series of mitochondria-targeted antioxidants comprising a lipophilic triphenylphosphonium cation attached to the antioxidant chroman moiety of vitamin E by an alkyl linker have been prepared. The synthesis of a series of mitochondria-targeted vitamin E derivatives with a range of alkyl linkers gave compounds of different hydrophobicities. This work will enable the dependence of antioxidant defence on hydrophobicity to be determined in vivo.

Crystal structures and conformational analyses of three pyranochromene derivatives.

The title compounds, C27H20O6, (I) [systematic name: methyl 7-oxo-14-phenyl-1H,7H,14H-pyrano[3,2-c:5,4-c']dichromene-14a(6bH)-carboxyl-ate], C24H22O5, (II) [systematic name: methyl 1-oxo-6-phenyl-2,3,4,12b-tetra-hydro-1H,6H-chromeno[3,4-c]chromene-6a(7H)-carboxyl-ate], and C25H23N3O4, (III) [systematic name: 6-(4-ethyl-phen-yl)-2,4-dimethyl-1,3-dioxo-2,3,4,12b-tetra-hydro-1H,6H-chromeno[4',3':4,5]pyrano[2,3-d]pyrimidine-6a(7H)-carbo-nitrile], are pyran-ochromene derivatives. The central pyran rings (B) of compounds (I) and (III) adopt half-chair conformations, whereas that of compound (II) adopts a sofa conformation. The pyran rings (A) of the chromene ring systems of compounds (II) and (III) adopt half-chair conformations, while that of compound (I) adopts a sofa conformation. The mean plane of the central pyran rings (B) make dihedral angles of 70.02 (6), 61.52 (6) and 69.12 (7)°, respectively, with the mean planes of the chromene moieties (C+A) of compounds (I), (II) and (III). The bicyclic coumarin ring system (C+A+B+E) in compound (I) is almost planar (r.m.s. deviation = 0.042 Å). The carbo-nitrile side chain in compound (III) is very nearly linear, with the C-CN angle being 176.6 (2)°. The cyclo-hexene ring (E), fused with the central pyran ring (B) in compound (II) adopts a sofa conformation. In the mol-ecular structures of compounds (II) and (III), there are C-H⋯O short contacts, which generate S(7) ring motifs. In the crystal structures of the title compounds, mol-ecules are linked by C-H⋯O hydrogen bonds, which generate mol-ecular sheets parallel to the ab plane, with R 4 (3)(28) loops in (I), inversion dimers with R 2 (2)(10) loops in (II) and chains along [010] with R 2 (2)(12) ring motifs in (III). In the crystal structures of (I) and (III), there are also C-H⋯π inter-actions present, leading to the formation of a three-dimensional framework in (II) and to sheets parallel to (101) in (III).

Photodamage attenuation effect by a tetraprenyltoluquinol chromane meroterpenoid isolated from Sargassum muticum

A tetraprenyltoluquinol meroterpenoid with a chromane moiety, obtained as an epimeric mixture at C3, was isolated for the first time from the dichloromethane fraction of a methanolic extract from the brown alga Sargassum muticum. The structure has been established by means of spectral methods including NMR spectroscopy and MS and comparison with reported data. The compound showed photodamage attenuation on irradiated cells with UVA light, presented protection against intracellular ROS generation in a degree comparable to retinoic acid (9.1–20.6%) and did not display toxicity against human dermal fibroblast cells.

Crystal Structure Theory and Applications of 14-Ethoxy-4,6,-dimethyl-8.12- dioxa-4.6-diazatetracyclo [8.8.0.02,7.013,18]octadeca-13,15,17-triene-3,5-dione

AbstractIn view of the growing medicinal importance of chromene and its derivatives, the single crystal X-ray diffraction studywas carried out for the potential active 4,6-dimethyl-9-phenyl-8,12-dioxa-4,6-diazatetracyclo [8.8.0.02,7.013,18]octadeca-2(7),13,15,17-tetraene-3,5,11-trione-2-ethoxyphenyl (2E)-but-2-enoate (C 18 H 20 N 2 O 5 ). In the title compound are twomolecules exist in the asymmetric unit. It crystallizes in the monoclinic space group P2 1 /c with unit cell dimensiona=14.608(3) A, b=12.845(3) and c= 17.781(4) [alpha & gamma=90 o beta=91.233(5) o ]. Both pyran and pyran ring of thechromene moiety adopts sofa conformation in the molecule A & B. The crystal structure is stabilized by intramolecularC-H...O hydrogen bond interaction.Keywords: Pyran; Chromene; Sofa Conformation; Single Crystal Structure; X-ray Diffraction (XRD) 1. Introduction The chromene moiety regularly appears as a principalstructural component in various biologically importantorganic compounds such as flavonoids, natural alka-loids, tocopherols and anthocyanins

Crystal structures of two hydrazinecarbo-thio-amide derivatives: (E)-N-ethyl-2-[(4-oxo-4H-chromen-3-yl)methyl-idene]hydrazinecarbo-thio-amide hemi-hydrate and (E)-2-[(4-chloro-2H-chromen-3-yl)methyl-idene]-N-phenyl-hydrazinecarbo-thio-amide.

The title compounds, C13H13N3O2S·0.5H2O, (I), and C17H14ClN3OS, (II), are hydrazinecarbo-thio-amide derivatives. Compound (I) crystallizes with two independent mol-ecules (A and B) and a water mol-ecule of crystallization in the asymmetric unit. The chromene moiety is essentially planar in mol-ecules A and B, with maximum deviations of 0.028 (3) and 0.016 (3) Å, respectively, for the carbonyl C atoms. In (II), the pyran ring of the chromene moiety adopts a screw-boat conformation and the phenyl ring is inclined by 61.18 (9)° to its mean plane. In the crystal of (I), bifurcated N-H⋯O and C-H⋯O hydrogen bonds link the two independent mol-ecules forming A-B dimers with two R 2 (1)(6) ring motifs, and R 2 (2)(10) and R 2 (2)(14) ring motifs. In addition to these, the water mol-ecule forms tetra-furcated hydrogen bonds which alternately generate R 4 (4)(12) and R 6 (6)(22) graph-set ring motifs. There are also π-π [inter-centroid distances = 3.5648 (14) and 3.6825 (15) Å] inter-actions present, leading to the formation of columns along the c-axis direction. In the crystal of (II), mol-ecules are linked by pairs of N-H⋯S hydrogen bonds, forming inversion dimers with an R 2 (2)(8) ring motif. The dimers are linked by C-H⋯π inter-actions, forming ribbons lying parallel to (210).

Asymmetric reduction of ketones by biocatalysis using medlar (Mespilus germanica L) fruit grown in Algeria

The biocatalytic reduction of ketones was performed using medlar fruit (Mespilus germanica L), which is grown in large amounts in Algeria. Experiments were performed using aqueous medium with fresh medlar. Prochiral heteroaryl ketones containing furan, thiophene, chroman, and thiochroman moieties were reduced with enantiomeric excess (ee) of up to 98%. High enantioselectivities have been observed especially for the bioreduction of tetralone 4 and thiochromanone 5 with ee of 89% and 98%, respectively. Bioreduction using different parts of medlar indicate that chromanone 6 was reduced with good asymmetric inductions 77% < ee < 85% whichever part of fruit was employed (whole, flesh, or juice) and medlar juice exhibited the best activity.

Design, Synthesis, and Biological Evaluation of New 2-Phenyl-4H-chromen-4-one Derivatives as Selective Cyclooxygenase-2 Inhibitors.

In order to develop new selective COX-2 inhibitors, a new series of 2-phenyl-4H-chromen-4-one derivatives possessing a methylsulfonyl pharmacophore group at the para position of the C-4 phenyl ring were designed, synthesized, and evaluated for cyclooxygenase-2 inhibitory activity. In vitro COX-1/COX-2 isozyme inhibition structure-activity studies identified 3-(benzyloxy)-2-[4-(methylsulfonyl)phenyl]-4H-chromen-4-one (5d) as a potent COX-2 inhibitor (IC50 = 0.07 μM) with a high COX-2 selectivity index (SI = 287.1) comparable to the reference drug celecoxib (COX-2 IC50 = 0.06 μM; COX-2 SI = 405). A molecular modeling study where 3-(benzyloxy)-2-[4-(methylsulfonyl)phenyl]-4H-chromen-4-one (5d) was docked into the active site of COX-2 showed that the p-MeSO2 substituent on the C-4 phenyl ring was well-oriented in the vicinity of the COX-2 secondary pocket (Arg513, Val523, and His90) and the carbonyl group of the chromene ring could interact with Ser530. The structure-activity data acquired indicated that the nature and size of the substituent on the C-3 chromene scaffold are important for COX-2 inhibitory activity. Our results also indicated that the chromene moiety constitutes a suitable template to design new COX-2 inhibitors.

Crystal structure of (E)-2-[(4-chloro-2H-chromen-3-yl)methyl-idene]-N-cyclo-hexyl-hydrazinecarbo-thio-amide.

In the title compound, C17H20ClN3OS, the mean plane of the central thio­urea core makes dihedral angles of 26.56 (9) and 47.62 (12)° with the mean planes of the chromene moiety and the cyclo­hexyl ring, respectively. The cyclo­hexyl ring adopts a chair conformation. The N–H atoms of the thio­urea unit adopt an anti conformation. The chromene group is positioned trans, whereas the cyclo­hexyl ring lies in the cis position to the thione S atom, with respect to the thio­urea C—N bond. In the crystal, mol­ecules are linked by N—H⋯S hydrogen bonds, forming inversion dimers enclosing R 2 2(8) ring motifs. The dimers are linked by C—H⋯Cl hydrogen bonds, enclosing R 6 6(44) ring motifs, forming sheets lying parallel to (010).

Crystal structure of 4-(4-meth-oxy-phen-yl)-7,7-dimethyl-2-methyl-amino-3-nitro-7,8-di-hydro-4H-chromen-5(6H)-one.

In the title compound, C19H22N2O5, the six-membered carbocyclic ring of the chromene moiety adopts an envelope conformation with the dimethyl-substituted C atom as the flap. The pyran ring has a flat-boat conformation. The meth­oxy­phenyl ring is orthogonal to the mean plane of the chromene moiety, with a dihedral angle of 89.97 (8)°. The amine N atom deviates from the chromene mean plane by 0.1897 (16) Å. The methyl­amine and the nitro group are involved in an intra­molecular N—H⋯O hydrogen bond which generates an S(6) ring motif. They are slightly twisted out of the plane of the chromene moiety with torsion angles of C—N—C—O(pyran) = 2.2 (3)° and O(nitro)—N—C—C = −5.6 (2)°. In the crystal, there are only C—H⋯π inter­actions present, forming inversion-related dimers.

7,7-Dimethyl-2-methyl-amino-4-(4-methyl-phenyl)-3-nitro-7,8-di-hydro-4H-chromen-5(6H)-one.

In the title compound, C19H22N2O4, the six-membered cyclo­hexenone ring of the chromene unit adopts an envelope conformation, with the dimethyl-substituted C atom as the flap, while the pyran ring has a boat conformation. These two mean planes are inclined to one another by 6.65 (13)°·The benzene ring is normal to the 4H-chromene moiety mean plane, making a dihedral angle of 89.18 (5)°. The methyl­amine and nitro groups are slightly twisted from the chromene moiety mean plane, with torsion angles C—N—C—O = 1.70 (18) and O—N—C—C = 0.15 (18)°. The mol­ecular structure is characterized by an intra­molecular N—H⋯O hydrogen bond, which generates an S(6) ring motif. In the crystal, mol­ecules are linked via pairs of weak C—H⋯O hydrogen bonds, forming inversion dimers. These dimers are connected by further C—H⋯O hydrogen bonds, forming sheets lying parallel to (10-1).

Design and synthesis of 3,4-dihydro-2H-benzo[h]chromene derivatives as potential NF-κB inhibitors

A novel class of NF-κB inhibitors were designed and synthesized based on KL-1156 (6-hydroxy-7-methoxychroman-2-carboxylic acid phenyl amide) which is unambiguously considered to be a promising inhibitor for the translocation step of NF-κB. Especially in this study we focused on the modifying the chroman moiety of KL-1156 into four parts for exploring the SAR studies linked with physical properties of substituents resulted the development of novel 1a–k, 2a–f, 3a–d and 4a–d derivatives of 3,4-dihydro-2H-benzo[h]chromene. From the SAR studies we were very delightfully identified that several new N-aryl-3,4-dihydro-2H-benzo[h]chromene-2-carboxamide derivatives (1a–k) exhibited good inhibitory activity and anti-proliferative activity than parent lead compound KL-1156, among them 1i exhibited outstanding inhibitory effect on LPS-induced NF-κB transcriptional activity and anti-proliferative activity on NCI-H23 lung cancer cell lines than KL-1156.

4-(4-Bromo-phen-yl)-7,7-dimethyl-2-methyl-amino-3-nitro-7,8-di-hydro-4H-chromen-5(6H)-one including an unknown solvate.

In the title compound, C18H19BrN2O4, the chromene unit is not quite planar (r.m.s. deviation = 0.199 Å), with the methyl C atoms lying 0.027 (4) and 1.929 (4) Å from the mean plane of the chromene unit. The six-membered carbocyclic ring of the chromene moiety adopts an envelope conformation, with the dimethyl-substituted C atom as the flap. The methyl­amine and nitro groups are slightly twisted from the chromene moiety, with C—N—C—O and O—N—C—C torsion angles of 2.7 (4) and −0.4 (4)°, respectively. The dihedral angle between the mean plane of the chromene unit and the benzene ring is 85.61 (13)°. An intra­molecular N—H⋯O hydrogen bond generates an S(6) ring motif, which stabilizes the mol­ecular conformation. In the crystal, mol­ecules are linked via N—H⋯O hydrogen bonds, forming hexa­gonal rings lying parallel to the ab plane. A region of disordered electron density, most probably disordered ethanol solvent mol­ecules, occupying voids of ca 432 Å3 for an electron count of 158, was treated using the SQUEEZE routine in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148–155]. Their formula mass and unit-cell characteristics were not taken into account during refinement.

Methyl 1-phenyl-3-p-tolyl-1,9b-di-hydro-3H-chromeno[4,3-c]isoxazole-3a(4H)-carboxyl-ate.

In the title compound, C25H23NO4, the pyran ring of the chroman moiety has an envelope conformation with the methyl­ene C atom as the flap. The isoxazole ring has a twist conformation on the O—C bond. The dihedral angle between their mean planes is 57.87 (9)°. The attached phenyl and benzene rings are twisted away from its mean plane by 56.19 (10) and 50.57 (10)°, respectively. These two rings are normal to each other, subtending a dihedral angle of 89.2 (1)°. In the crystal, there are no classical hydrogen bonds; the mol­ecules are linked via C—H⋯π inter­actions, forming a two-dimensional network lying parallel to (10-1).

(7-Chloro-2-oxo-2H-chromen-4-yl)methyl diethylcarbamodithioate

In the title compound, C15H16ClNO2S2, the 2H-chromene ring system is nearly planar, with a maximum deviation of 0.023 (2) Å. In the crystal, C—H⋯O hydrogen bonds give R 2 1(7) motifs, which generate [100] chains. C—H⋯π and π–π inter­actions between chromene moieties [shortest ring centroid–centroid distance = 3.6199 (13) Å] consolidate the packing.

4-(4-Bromophenyl)-2-methylamino-3-nitro-5,6,7,8-tetrahydro-4H-chromen-5-one

In the title compound, C16H15BrN2O4, the six-membered carbocyclic ring of the chromene moiety adopts an envelope conformation with the disordered methyl­ene C atom as the flap. The pyran ring is almost orthogonal to the chloro­phenyl ring, making a dihedral angle of 87.11 (12)°. The amine-group N atom deviates significantly from the pyran ring [0.238 (3) Å]. The mol­ecular structure is stabilized by an intra­molecular N—H⋯O hydrogen bond, which generates an S(6) ring motif. In the crystal, mol­ecules are linked via C—H⋯O hydrogen bonds, which generate C(8) chains running parallel to the b axis. The chains are linked by C—H⋯π inter­actions. The methyl­ene-group C atom of the chromene system that is disordered, along with its attached H atoms and the H atoms on the two adjacent C atoms, has an occupancy ratio of 0.791 (7):0.209 (7).

2-Amino-4-(4-fluorophenyl)-6-methoxy-4H-benzo[h]chromene-3-carbonitrile

In the title mol­ecule, C21H15FN2O2, the dihedral angle between the fluoro-substituted benzene ring and the mean plane of the 4H-benzo[h]chromene ring system [maximum deviation = 0.109 (2) Å] is 83.35 (7)°. The pyran ring adopts a slight sofa conformation with the tertiary C(H) atom forming the flap. The meth­oxy group is slightly twisted from the attached benzene ring of the 4H-benzo[h]chromene moiety [C—O—C—C = −4.3 (3)°]. In the crystal, mol­ecules are linked by inter­molecular N—H⋯N hydrogen bonds into infinite wave-like chains along the b axis. The crystal packing is further stabilized by π–π inter­actions [centroid–centroid distance = 3.7713 (9) Å].

Ethyl 2-amino-4-(4-fluorophenyl)-6-methoxy-4H-benzo[h]chromene-3-carboxylate

In the title compound, C23H20FNO4, the fluoro-substituted benzene ring is approximately perpendicular to the mean plane of the 4H-benzo[h]chromene ring system [maximum deviation = 0.264 (1) Å], with a dihedral angle of 83.79 (6)°. The pyran ring adopts a flattened boat conformation. The meth­oxy group is slightly twisted from the attached benzene ring of the 4H-benzo[h]chromene moiety [C—O—C—C = −2.1 (2)°]. An intra­molecular N—H⋯O hydrogen bond generates an S(6) ring motif. In the crystal, mol­ecules are linked by N—H⋯O and N—H⋯F hydrogen bonds into a layer parallel to the bc plane. The crystal packing also features C—H⋯π inter­actions.

Water soluble photoactive cellulose derivatives: synthesis and characterization of mixed 2-[(4-methyl-2-oxo-2H-chromen-7-yl)oxy]acetic acid–(3-carboxypropyl)trimethylammonium chloride esters of cellulose

Photoactive derivatives of cellulose were prepared by a mild esterification of the biopolymer with 2-[(4-methyl-2-oxo-2H-chromen-7-yl)oxy]acetic acid via the activation of the carboxylic acid with N,N′-carbonyldiimidazole. Subsequently, modification with the cationic carboxylic acid (3-carboxypropyl)trimethylammonium chloride was carried out. Thus, water soluble polyelectrolytes decorated with high amounts of photochemically active chromene moieties were obtained. The structures of the novel polysaccharide esters and the polyelectrolytes were evaluated by means of NMR and IR spectroscopy. Moreover, the light triggered photodimerization of the chromene moieties of the photoactive polyelectrolytes was studied by means of UV–Vis spectroscopy in the dissolved state. The photochemistry observed may be used to control the properties of the new polysaccharide derivatives and are thus of interest in the design of smart materials.

A rhodamine chromene-based turn-on fluorescence probe for selectively imaging Cu2+ in living cell

We describe the development of a rhodamine chromene-based turn-on fluorescence probe to monitor the intracellular Cu2+ level in living cells. The new fluorescent probe with a chlorine group in chromene moiety exhibits good membrane-permeable property than previous reported because the predicted lipophilicity of present probe 4 is stronger than that of methoxyl substituted probe in our previous work (CLogP of 4: 8.313, CLogP of methoxyl substituted probe: 7.706), and a fluorescence response toward Cu2+ under physiological conditions with high sensitivity and selectivity, and facilitates naked-eye detection of Cu2+. The fluorescence intensity was remarkably increased upon the addition of Cu2+ within 1 or 2min, while the other sixteen metal ions caused no significant effect.