Structures of spiropyrans exhibiting photochromic properties in the solid state

Russian Chemical Bulletin - Solid-state photochromic indoline spiropyrans bearing a formyl group at the 6′ and 8′ positions of the 2H-chromene moiety of the molecules were...     

Synthesis of function-oriented 2-phenyl-2H-chromene derivatives using L-pipecolinic acid and substituted guanidine organocatalysts

Organocatalytic domino oxa-Michael/aldol reactions between salicylaldehyde with electron deficient olefins are presented. We screened guanidine, 1,1,3,3-tetramethylguanidine (TMG) and L-pipecolinic acid as organocatalysts for this transformation. 3-Substituted 2-phenyl-2H-chromene derivatives are synthesized with high yields and with poor enantioselectivity (5-17% ee) using L-pipecolinic acid while TMG works well with cinnamaldehyde without using co-catalyst. These 3-substituted-2-phenyl-2H-chromene derivatives are further derivatized to synthesize triazole and biotin-containing chromene derivatives, to facilitate purification of protein targets.     

Cascade reaction of β,γ-unsaturated α-ketoesters with phenols in trityl chloride/TFA system. Highly selective synthesis of 4-aryl-2H-chromenes and their applications

The treatment of β,γ-unsaturated α-ketoesters with phenols in the presence of trityl chloride and 4 ? molecular sieves in refluxing trifluoroacetic acid afforded 4-aryl-2H-chromenes in high yields, in which a reverse of the regiochemistry of J?rgensen-Rutjes chromane synthesis was observed. The isolation of 4H-chromene intermediates, confirmed by single-crystal X-ray analysis, indicates that the early stage of the reaction involves a Friedel-Crafts alkylation/cyclodehydration processes. Stirring of the 4H-chromene intermediate with trityl chloride in deuterotrifluoroacetic acid under reflux afforded the 2H-chromene and triphenylmethane in high yields, which implies the late stage of the reaction involves a hydrogen transfer process. Highly selective derivation of the hydroxyl esters to the corresponding hydroxyl amides, amino acids, amino esters and Friedel-Crafts adducts was further accomplished. Our endeavors will lead to a better understanding of the controlling elements behind their structural motifs. The products were confirmed unambiguously from their spectra and by single-crystal X-ray analysis.     

Synthesis and cytotoxic activity of 11-nitro and 11-amino derivatives of acronycine and 6-demethoxyacronycine

Condensation of 2-chloro-3-nitrobenzoic acid with either 5-amino-7-methoxy-2,2-dimethyl-2H-chromene or 5-amino-2,2-dimethyl-2H-chromene afforded diphenylamines 14 and 15. Trifluoroacetic anhydride mediated cyclization gave the corresponding acridones 16 and 17, which were subsequently N-methylated and reduced to 11-aminoacronycine and 11-amino-6-demethoxyacronycine. These two amino compounds, which gave stable water soluble salts, were 2- to 3-fold more potent than acronycine or 6-demethoxyacronycine in inhibiting L1210 cell proliferation.     

One-pot synthesis of some 2-amino-4H-chromene derivatives using triethanolamine as a novel reusable organocatalyst under solvent-free conditions and its application in electrosynthesis of silver nanoparticles

Russian Journal of General Chemistry - A wide variety of 2-amino-4H-chromene derivatives with diverse substituents on the 4H-chromene ring were efficiently prepared via one-pot three-component...     

Bi（OTf）3-catalyzed tandem reaction of naphthols with β,γ-unsaturated α-ketoesters. Efficient synthesis of functionalized 4H-chromenes

An efficient synthesis of functionalized 4H-chromenes by the tandem reaction of β,γ-unsaturated α- ketoesters with 2-naphthols, 1 -naphthols, and 1,3-dihydroxynaphthalenes has been accomplished with high selectivity and excellent yields in the presence of a catalytic amount of bismuth triflate [Bi（OTf）3, 5 mol%] under mild conditions. The functionalized 4H-chromene synthesis and our previous 2H- chromene hemiacetal synthesis could complement each other to enrich reaction diversity.     

Phenylboronic acid mediated triple condensation reactions of phloroglucinol and unsaturated carbonyl compounds

[reaction: see text] A remarkable phenylboronic acid mediated triple condensation reaction of phloroglucinol (1,3,5-trihydroxybenzene) with a series of alpha,beta-unsaturated carbonyl compounds is reported. This experimentally simple reaction afforded novel C3-symmetric 2H-chromene derivatives. These derivatives represent structural analogues of the natural product xyloketal A, which has been reported to be a potent inhibitor of acetylcholine esterase.     

Formation of benzofuran and 2H-chromene structures in one reaction. A novel synthesis of 2H-chromene derivatives

Heating the morpholinal of nitrosalicylic aldehyde with methyl propiolate in acetonitrile in the presence of Cul affords an equimolar mixture of 2-methoxycarbonylmethyl-3-morpholino-5-nitrobenzofuran and 3-methoxycarbonyl-2-morpholino-6-nitro-2H-chromene, the structures of which were determined by X-ray analysis. Only the 2H-chromene mentioned above was obtained in the absence of Cul and solvent.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1222–1228, May, 1996.     

Molecular structure of 2-(p-tolyl)ammo-5, 6-benzo-2H-chromene

An X-ray structural investigation (1274 reflections,R=0.057) has established that 2-(ptolyl)amino-5, 6-benzo-2H-chromene exists in the crystalline state as a cyclic 2H-chromene tautomer. This molecule is nonplanar due to the tetrahedral coordination of the C(1) atom and the relative rotation of phenyl and benzochromene rings.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 515–517, March, 1993.     

Design,Synthesis, and Antimicrobial Activity of (E)-4-Phenyl-2H-chromene-3-carbaldehyde O-[(1-Phenyl-1H-1,2,3-triazol-4-yl)methyl]oxime Derivatives

Russian Journal of Organic Chemistry - A new series of 1,4-disubstituted 1,2,3-triazole derivatives tethered to a 2H-chromene scaffold have been synthesized via a click reaction. The synthesized...     

Acid-induced photochromic system switching of diarylethene derivatives between P- and T-types

P-type photochromic diarylethenes having a diethylamino group can switch to T-type photochromic system by the addition of trifluoromethanesulfonic acid as external stimuli.     

Nucleophilic Vinylic Substitution in Perfluoroacylchromenes. Diastereoselective Synthesis of Push–Pull Enamino Ketones

Russian Journal of Organic Chemistry - The reactions of 2-perfluoroacyl-1H-benzo[f]chromenes and 6,7-dimethyl-3-trifluoroacetyl-4H-chromene with primary aliphatic amines and ammonia afforded a...     

Ring-chain tautomerism and thermo- and photochromism of 3-(1-hydroxy-4-methyl-2-naphthyl)propenal imines

A series of previously undescribed 3-(1-hydroxy-4-methyl-2-naphthyl)propenal imines was synthesized. In the crystalline state all of the imines, except the N-(p-nitrophenyl)imine, have an open o-quinoid structure, whereas in solutions in nonpolar solvents they exist in the cyclic 2H-chromene form. In polar solvents the imines display ring-chain tautomeric equilibrium of the 2H-chromene and o-quinoid forms, the relative percentages of which are determined by the character of the substituent in the amino component of the molecule and by the polarity of the solvent. The N-(p-nitrophenyl)imine has-the 2H-chromene structure in the solid phase and in solvents.Communication 14 from the series Photochromic and thermochromic spirans. See [1] for communication 13.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1031–1039, August, 1983.     

Synthesis and analgesic activity of octahydro-2H-chromenols,derivatives of aliphatic ketones

Russian Chemical Bulletin - A series of compounds with a hydrogenated 2H-chromene skeleton was synthesized by the reaction of ketones and available para-menthane monoterpenoid (—)-isopulegol....     

与二茂铁酰基相连的螺噁嗪的合成、结构及性质

在二环已基碳二亚胺(DCC)存在下, 将9′-羟基螺噁嗪与二茂铁甲酸进行酯化缩合, 合成了一种与二茂铁酰基相连的螺噁嗪衍生物2, 用核磁共振氢谱、碳谱、红外光谱、高分辨质谱和X射线单晶衍射对其结构进行了表征. 化合物2在几种有机溶剂中都表现出了良好的光致变色性质; 通过实验证明了在无冰水浴冷却条件下, 用高压汞灯照射时化合物2在二氯甲烷中表现出的特殊变色性是酸致变色的结果; 同时还研究了化合物2在固体PMMA薄膜中的光致变色性质. 在高压汞灯照射下,化合物2在二氯甲烷溶液中显示了良好的荧光性. 循环伏安法测定结果表明化合物2具有良好的氧化还原可逆性.     

A colorimetric and fluorescent turn-on sensor for pyrophosphate anion based on a dicyanomethylene-4H-chromene framework

A new red fluorescent sensor DCCP-Cu2+ based on dicyanomethylene-4H-chromene shows turn-on fluorescence with high selectivity for pyrophosphate over other anions.     

Novel one-pot synthesis of 4H-chromene derivatives using amino functionalized silica gel catalyst

A simple, efficient, and environmentally benign method for the synthesis of 4H-chromene derivatives was developed using well ordered and recoverable amino functionalized silica gel as a base catalyst. The 4H-chromene derivatives were obtained in short time and excellent yield(87%–96%) by three component reaction of aldehydes, malononitrile and cyclic 1,3-diketones in water at 70 8C.     

磺酸功能化的离子液体型多金属氧酸盐的光色性能

发现磺酸功能化离子液体型多金属氧酸盐(IL-POM)具有可逆光色性质,并在紫外光激发下,详细考察了[PyPS]_nH_3-nPW₁₂(n=1,3)(PyPs:吡啶丙磺酸盐)、[PyPS]₄SiW₁₂、[TEAPS]₃PW₁₂(TEAPS:3-(三乙胺基)丙磺酸盐)等样品的光致变色行为。 结果表明,磺酸化的IL-POM是一类弱的电荷转移多金属氧酸盐,但在紫外光激发下有机阳离子和POM阴离子间可以发生电子相互作用,实现W⁶⁺→W⁵⁺的还原,并形成稳定的电荷转移复合物,导致样品显色。 钨磷酸盐的光色性大大强于钨硅酸盐,且空气中避光放置可以消色。 但样品容易疲劳,着色-褪色重复性不好。 对光色机理的研究显示,有机阳离子中的-SO₃H基团作为电子供体参与了变色过程。 揭示了磺酸基团的电子供体作用,为设计电荷转移多金属氧酸盐和POM基光色材料提供了新的思路。     

Synthèse du benzoyl-3 chromanol-4 et du benzoyl-3 2H-chromène

Reaction between phenylvinylketone and salicylaldehyde under basic conditions gave a mixture of 3-benzoyl-4-chromanol and 3-benzoyl-2H-chromene. Their structures were determined on the basis of analytical and spectroscopic data.     

Visible-light Photochromism of Phosphomolybdic Acid/ZnO Composite

A novel photochromic hybrid ZnO was synthesized by doping with phosphomolybdic acid(PMoA). It could respond to visible light and fade in color when treated with hydrogen peroxide(H₂O₂). The microstructure and photochromic properties were investigated via X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FTIR), scanning electron microscopy(SEM), transmission electron microscopy(TEM), ultraviolet-visible spectroscopy(UV-Vis) and X-ray photoelectron spectroscopy(XPS). The XRD patterns show that the prepared ZnO is pure and has a hexagonal wurtzite structure. The FTIR results demonstrate the existence of a strong interaction between PMoA and ZnO. Due to PMoA doping, the rough surface morphology of ZnO became smooth, as verified by the SEM images. The TEM images illustrate that pure ZnO exhibits a polycrystalline structure with irregular morphology. PMoA was wrapped on the surface of ZnO. After visible-light irradiation, the composite changed from slight yellow to blue and returned to the original color in the presence of H₂O₂. The composite had good photosensitivity and photochromic reversibility. The photochromic process was in accord with photoinduced electrons transfer mechanism.