Synthesis of Bridged Tetrahydrobenzo[b]azepines and Derivatives through an Aza‐Piancatelli Cyclization/Michael Addition Sequence

Herein, we report the preparation of bridged tetrahydrobenzo[b]azepines, which was accomplished through an aza‐Piancatelli cyclization/Michael addition sequence in a one‐pot fashion from readily available precursors. It is noteworthy that a general method to access these scaffolds was hitherto unprecedented. Additionally, the multifaceted aspects of this process have been exemplified through its application to the synthesis of 2‐azabicyclo[3.2.1]octanes and bridged tetrahydrobenzo[b]oxepines, along with post‐derivatizations.     

A Mild and Environmentally Benign Synthesis of Tetrahydrobenzo[b]pyrans and Pyrano[c]chromenes Using Pectin as a Green and Biodegradable Catalyst

Pectin was applied as a green and biodegradable catalyst for the one‐pot three‐component synthesis of tetrahydrobenzo[b]pyrans and pyrano[c]chromenes, from the condensation between aromatic aldehydes, malononitrile, and dimedone or 4‐hydroxycumarine at ambient temperature. This protocol has many advantages such as mild conditions, high yields, environmental benignity, simple work‐up procedures, short reaction time, as well as the use of a natural, easily accessible, convenient handling, and inexpensive catalyst. Another advantage of this method is that the products do not require further purification such as column chromatography.     

水相中无催化剂合成四氢苯并吡喃衍生物

水相中无催化剂合成了2-氨基-7,7-二甲基-5-氧代-4-芳基-4H-苯并吡喃-3-氰基-5,6,7,8-四氢苯并[b]吡喃,其结构经1H NMR,IR和元素分析表征。     

One‐pot Synthesis of Tetrahydrobenzo[b]pyrans Catalyzed by PEG‐1000 Bridged Primary Amine Functionalized Dicationic Ionic Liquid in Water

A novel poly (ethylene glycol) bridged primary amine functionalized dicationic ionic liquid ([PA‐PEG₁₀₀₀‐DIL][BF₄]) was synthesized and characterized by ¹H‐NMR, ¹³C‐NMR, FT‐IR and ESI‐MS. The thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis indicated the high thermal stability of [PA‐PEG₁₀₀₀‐DIL][BF₄]. It was used as an efficient and recyclable catalyst for the synthesis of substituted tetrahydrobenzo[b]pyrans through a one‐pot three‐component condensation of aromatic aldehydes, malononitrile and dimedone in 86% ～ 96% yields within 10 ～ 30 min in water. This method offers several advantages such as mild reaction conditions, simple operation and environmental friendliness. Furthermore, the catalyst could be easily recovered and reused for at least five runs without obvious loss of catalytic activity.     

A Green Synthesis of Tetrahydrobenzo[b]pyran Derivatives through Three-Component Condensation Using N-Methylimidazole as Organocatalyst

Summary. An efficient and convenient approach to the synthesis of 2-amino-3-cyano-4-aryl-7,7-dimethyl-5-oxo-4H-5,6,7,8-tetrahydrobenzo[b]pyran derivatives using N-methylimidazole as the organocatalyst (20 mol%) is described. This method has several advantages, such as mild conditions, high yields, and simple work-up procedure.     

无溶剂研磨条件下四氢苯并吡喃衍生物的一锅法合成

四氢苯并吡喃衍生物在药物和农药研究中有着广泛的用途. 基于合成这类化合物的传统方法所用溶剂多为对环境不利的极性溶剂, 且合成需分步进行, 在提倡绿色化学和发展节约型经济的今天, 如何改良这类反应已成为一个热点. 本工作通过选择不同的碱尝试反应最佳条件, 发现用价廉易得的碳酸钾为碱, 对不同官能团取代的底物芳醛采用研磨的手段, 在无溶剂条件下, 一锅法可成功合成四氢苯并吡喃衍生物. 该法条件温和, 收率高, 易于操作, 对环境影响小.     

2-(2,6-二烷氧基苯基)苯并呋喃衍生物的合成

以焦性没食子酸、4-羟基苯甲醛和酚为原料, 以邻碘代苯酚与苯乙炔衍生物的Sonogashira偶联及其连串化反应生成苯并呋喃环为关键步骤, 设计合成了一系列2-(2 ,6 -二烷氧基苯基)苯并呋喃衍生物, 并对产物进行了¹H NMR, ¹³C NMR, MS等表征.     

2-取代芳基苯并呋喃类化合物的合成

以香草醛和丙二酸为原料,经Knoevenagel缩合、酯化、仿生氧化偶联、DDQ脱氢、还原和氧化等反应合成了3种新的2-取代芳基苯并呋喃类化合物,其结构经1H NMR,IR和MS表征。两分子阿魏酸甲酯仿生氧化偶联为它的二聚体是合成的关键步骤。     

I2-Promoted Intramolecular Oxidative Cyclization of Butenyl Anilines: A Facile Route to Benzo[b]azepines

A metal-free approach for the synthesis of seven-membered N-heterocycles has been developed by the I₂-promoted intramolecular cross-coupling/annulation of butenyl anilines. This cyclization reaction involves C−H activation and C−C bond formation and exhibits good functional group tolerance. A series of benzo[b]azepine derivatives are obtained in moderate to good yields.     

Molecular Iodine: An Efficient Catalyst for the Synthesis of Tetrahydrobenzo[b]pyrans

An iodine/DMSO system is introduced as an excellent catalyst in three‐component coupling reactions of tetrahydrobenzo[b]pyran synthesis. The reaction proceeds quickly under very mild reaction conditions.     

Efficient One-Pot,Four-Component Synthesis of 1,2,3-Triazole-Linked Tetrahydrobenzo[b]pyrans

A one-pot procedure has been developed for the synthesis of (1,2,3-triazolyl) methoxyphenyl tetrahydro-5-oxo-4H-chromene derivatives by concurrent reaction of aryloxy propargylated aldehydes, various azides, active methylene compounds, and 1,3-cyclohexanediones using catalytic amounts of Cu(OAc)₂ / sodium ascorbate and diammonium hydrogen phosphate in aqueous ethanol media. Excellent conversion of starting materials was achieved to the desired (1,2,3-triazolyl) methoxyphenyl tetrahydro-5-oxo-4H-chromene products.     

Synthesis of [1,2,3]Triazolo[5,1-a]isoquinoline Derivatives via a Selective Cascade Cyclization Sequence of 1,2-bis(Phenylethynyl)benzene Derivatives

A direct, concise, synthetic method for the generation of [1,2,3]triazolo[5,1-a]isoquinoline derivatives, using a selective cascade cyclization of unsymmetrical substituted 1,2-bis(phenylethynyl)benzene derivatives with NaN₃, has been developed. The reaction gave different substituted [1,2,3]triazolo[5,1-a]isoquinolines in moderate to good yields. It was found that the substituents on the alkynes were important for the selectivities of the cascade cyclization sequences.     

1,4-Diazabicyclo[2.2.2]octane as an Efficient Catalyst for a Clean,One-Pot Synthesis of Tetrahydrobenzo[b]pyran Derivatives via Multicomponent Reaction in Aqueous Media

1,4-Diazabicyclo[2.2.2]octane (DABCO) has been used as a mild and efficient catalyst for the synthesis of various tetrahydrobenzo[b]pyran derivatives via a one-pot, three component condensation of aromatic aldehydes, dimedone, and active methylene compounds. This method provides several advantages: a simple workup procedure, environmental friendliness, neutral conditions, and good yields. In addition, water or 50% aqueous ethanol was chosen as a green solvent.

Conformational isomers in the photocyclodimerization of N-acylated dibenz[b,f]azepine derivatives

The benzophenone-sensitised photodimerizations of N-acetyl- and N-propionyldibenz[e,f]azepine were investigated in acetone as the solvent. In both the systems, the ¹H NMR analysis of the products revealed two isomeric photodimers differing in the chemical shifts and coupling constants of the cyclobutane protons, aromatic protons and the protons of the acetyl or propionyl group. Upon raising the temperature to ca. 70 °C the signals merge. The findings can be ascribed to a single thermally restricted conformational process such as the rotation about the C–N amide bond. The process exhibits free activation energies: ΔG^#=(74±2) kJ mol⁻¹ (N-acetyl) and ΔG^#=(70±2) kJ mol⁻¹ (N-propionyl).     

2-取代芳基苯并[b]呋喃类化合物的合成

以4-取代苯乙炔化亚铜与3-甲氧基-4-羟基-5-溴肉桂酸甲酯为原料进行缩合反应得到2-取代芳基并[b]呋喃, 并将其衍生化, 得到14个2-芳基-5-烷基-7-甲氧基苯并[b]呋喃化合物, 并确证了其结构.     

二苯并[b,f][1,5]二氮杂芳辛四烯衍生物的合成及拆分

以邻氨基二苯甲酮为原料,经自身缩合环化合成了3种二苯并[1,5]二氮杂芳辛四烯衍生物(1a~1c);以邻苯二甲酸酐和溴苯为原料经傅-克反应制得中间体2-(4-溴苯甲酰溴)苯甲酸(M1);M1经叠氮化后自缩合制得6,12-二(4-溴苯基)二苯并[b,f][1,5]二氮杂环辛四烯(1d);以邻氨基苯甲酸甲酯为原料,经自身缩合环化制得中间体二苯并[b,f][1,5]二氮杂环辛四烯-6,12(5H,11H)-二酮(M2);M2经氯化合成6,12-二氯二苯并[b,f][1,5]二氮杂环辛四烯(1e),化合物1a~1e的结构经~1H NMR,~(13)C NMR和ESI-MS表征,其中化合物1c为新化合物。利用超临界色谱(SFC)技术对化合物1a~1e实现了手性拆分,获得5对具有高旋光度的光学活性异构体(ee99%)。     

二碘化钐催化合成1,5-苯并二氮杂草

Samarium diiodide （SmI2） was found to be an efficient catalyst for the condensation of o-phenylenediamine and ketones to afford the corresponding 2,3-dihydro-1H-benzo[b][1,4]-diazepines in moderate to excellent yields under very mild and solvent-free conditions. The real active species here was suggested to be a Sin（Ⅲ） intermediate formed in situ and the mechanism of the present reaction was proposed.     

碱性季铵盐“一锅法”催化合成四氢苯并[b]吡喃的水相反应研究

报道了以2-二甲氨乙基苄基二甲基氯化铵为催化剂,在水相介质中"一锅法"催化芳醛、丙二腈和5,5-二甲基-1,3-环己二酮合成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]吡喃的方法.该法具有产率高、反应时间短、操作简便、对环境友好、催化剂可重复使用等优点.     

纳米 Ce1MgxZr1-xO2 固体多相催化剂的制备、表征及催化合成四氢苯并[b]吡喃衍生物的性能

 A series of Ce1MgxZr1-xO2 mixed metal oxides with different molar ratios were prepared by simple co-precipitation and were characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, temperature-pro- grammed desorption of CO2, and N2 adsorption techniques. The prepared materials were tested for catalytic activity by the synthesis of tet-rahydrobenzo[b]pyran derivatives using a three component reaction (aromatic aldehydes, malononitrile, and dimedone) in an ethanol me-dium. The best catalytic activity was obtained with Ce1Mg0.6Zr0.4O2. The particle size or crystallite size was estimated using the De-bye-Scherrer equation. The addition of magnesium oxide into the ceria-zirconia lattice resulted in the formation of nanosized particles rang-ing from 5.41 to 9.78 nm. This work describes the catalytic behavior of magnesium oxide in mixed metal oxide systems.     

Michael Addition Reaction without Catalyst：The Synthesis of 2—Amino—5,6,7,8—tetrahydro—5—oxo—4—aryl—7,7—dimethyl—4H—benzo—[b]—pyran Derivatives

A serices of tetrahydrobenzo-[b]-pyran derivative was synthesized by the reaction of arylmethylene malononitrile or arylmethylene cyanoacetate with dimedone in ethylene gylcol at 80℃ without catalyst. The structures of the two products were characterized by X-ray diffraction.