Reductive coupling of polyfunctionalized organobismuth and organolead arylating reagents in the synthesis of benzopyran derivatives

Benzopyran derivatives were synthesized in good yields by the reactions of tris[2-(chloromethyl)phenyl]bismuth diacetate and 2-(halomethyl)aryllead triacetates with phenols and naturally occurring 4-hydroxycoumarins in the presence of bases according to a three-step one-pot procedure. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2520–2529, November, 2005.     

One-step synthesis of substituted 2-amino-5,6,7,8-tetrahydro-4H-benzo[b]pyrans. Molecular and crystal structure of 2-amino-3-(2-methoxyethoxycarbonyl)-4-(2-nitrophenyl)-5-oxo-5,6,7,8-tetrahydro-4H-benzo[b]pyran

Substituted 2-aminobenzo[b]pyrans were synthesized by three-component condensation of aromatic aldehydes, cyanoacetic acid derivatives, and cyclic 1,3-diketones. The molecular and crystal structure of 2-amino-3-(2-methoxyethoxycarbonyl)-4-(2-nitrophenyl)-5-oxo-5,6,7,8-tetrahydro-4H-benzo[b]pyran was established by X-ray diffraction analysis.     

甲氧羰基亚甲基三苯基胂与邻羟基芳醛,酮的反应-5,6-苯并-2-吡喃酮的合成

本文报道一种合成烃基取代5,6-苯并-2-吡喃酮的方法。甲氧羰基亚甲基三苯基胂与烃基取代的邻羟基芳醛、酮反应,首先生成α,β-不饱和酸酯,继而发生分子内环化,生成烃基取代的5,6-苯并-2-吡喃酮。     

Easy synthesis of heterocyclic carbene complexes by activation of chalcogenopyrones and benzopyrones to pyrylium salts and subsequent addition of carbanion of methoxy(methyl)pentacarbonyltungsten carbene complex

Methylenechalcogenopyran and benzopyran Fischer carbene complexes are easily obtained from commercially available chalcogenopyrones or benzopyrones and carbanion of methoxy(methyl)carbene tungsten complex. The key of the heterocyclic carbene formation is the activation of the carbonyl group by alkylation with alkyl trifluoromethanesulfonate reagent.     

Three polymorphs of 3‐(3‐phenyl‐1H‐1,2,4‐triazol‐5‐yl)‐2H‐1‐benzopyran‐2‐one formed from different solvents

The polymorphic study of 3‐(3‐phenyl‐1H‐1,2,4‐triazol‐5‐yl)‐2H‐1‐benzopyran‐2‐one, C₁₇H₁₁N₃O₂, was performed due to its potential biological activity and revealed three polymorphic modifications in the triclinic space group P, the monoclinic space group P2₁ and the orthorhombic space group Pbca. These polymorphs have a one‐column layered type of crystal organization. The strongest interactions between the molecules of the studied structures is stacking between π‐systems, while N—H…N and C—H…O hydrogen bonds link stacked columns forming layers as a secondary basic structural motif. C—H…π hydrogen bonds were observed between neighbouring layers and their role is the least significant in the formation of the crystal structure. Packing differences between the polymorphic modifications are minor and can be identified only using an analysis based on a comparison of the pairwise interaction energies.     

超声辐射下一步法合成2-氨基-3-氰基-4-芳基-7，7-二甲基-5-氧代-5，6，7，8-四氢-4H-苯并[b]吡喃

芳醛、丙二腈和5，5-二甲基-1，3-环己二酮在乙二醇中不加任何催化剂经超 声辐射5-7min得2-氨基-3-氰基-4-芳基-7，7-二甲基-5-氧代-4H-5，6，7，8-四氢 苯并[b]吡喃，产率88％—96％．     

Facile One‐Pot Synthesis of 3‐{2‐[5‐Hydroxy‐4‐(2‐hydroxy‐ethyl)‐3‐methyl‐pyrazol‐1‐yl]‐thiazol‐4‐yl}‐chromen‐2‐ones via a Three‐Component Reaction

Reaction of 3‐(2‐bromo‐acetyl)‐chromen‐2‐one with thiosemicarbazide and 2‐acetylbutyro lactone in anhydrous ethanol gave 3‐{2‐[5‐hydroxy‐4‐(2‐hydroxy‐ethyl)‐3‐methyl‐pyrazol‐1‐yl]‐thiazol‐4‐yl}‐chromen‐2‐one in good yields.     

Photochromic reverse mode polymer dispersed liquid crystals

Control of light intensity and colour are two of the major features required in the realization of smart windows. We designed a bi‐functional polymer dispersed liquid crystal (PDLC) film in order to satisfy such requirements, i.e. it is able both to modulate the optical transmission, if an external electric field is applied, and to change colour if exposed to sunlight. A monomer/liquid crystal mixture was doped with a small amount of photochromic material and homeotropically aligned by means of rough surfaces. A transparent and pale pink coloured film was achieved after photopolymerization. Such a film changes colour upon exposure for some seconds to sunlight or ultraviolet radiation in a persistent but reversible manner. In addition, the film appears transparent without the application of an electric field (OFF state) and becomes opaque on application of a driving voltage of about 75?V (ON state), and thus the film operates in reverse mode with respect to conventional PDLCs.     

o-Formylation of electron-rich phenols with dichloromethyl methyl ether and TiCl4

o-Formylation of electron-rich phenols is accomplished with dichloromethyl methyl ether and TiCl₄. The reaction gives excellent yields, good regioselectivity, and does not leading to diformylation.     

无催化剂条件下微波辐射一步法合成2-氨基-4-芳基-5-氧代-5,6,7,8-四氢-4H-苯并吡喃-3-腈

以芳醛、丙二腈、1,3-环己二酮为原料在无催化剂条件下,分别用微波辐射和传统加热法合成了一系列2-氨基-4-芳基-5-氧代-5,6,7,8-四氢-4H-苯并吡喃-3-腈(4a～4g)衍生物.与常规加热方法相比,微波辐射法具有反应时间短、产率高、后处理方便、环境友好等优点,所有化合物均经IR,1H MMR和元素分析确定.