- A quick and advantageous synthesis of 2H-1-benzopyran-2-ones unsubstituted on the pyranic nucleus
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The synthesis of 2H-1-benzopyran-2-ones (coumarins) unsubstituted on the pyranic nucleus was realized by condensation of malic acid and phenols under mild conditions. A short reaction time, improved yields, good purity of the products, and an easy clean experimental protocol are the advantages of this procedure. Georg Thieme Verlag Stuttgart.
- Bratulescu, George
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- Gold(I)-Catalyzed Intramolecular Hydroarylation of Phenol-Derived Propiolates and Certain Related Ethers as a Route to Selectively Functionalized Coumarins and 2 H-Chromenes
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Methods are reported for the efficient assembly of a series of phenol-derived propiolates, including the parent system 56, and their Au(I)-catalyzed cyclization (intramolecular hydroarylation) to give the corresponding coumarins (e.g., 1). Simple syntheses of natural products such as ayapin (144) and scoparone (145) have been realized by such means, and the first of these subject to single-crystal X-ray analysis. A related process is described for the conversion of propargyl ethers such as 156 into the isomeric 2H-chromene precocene I (159), a naturally occurring inhibitor of juvenile hormone biosynthesis.
- Cervi, Aymeric,Vo, Yen,Chai, Christina L. L.,Banwell, Martin G.,Lan, Ping,Willis, Anthony C.
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p. 178 - 198
(2020/12/22)
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- Organometallic iridium complex phosphorescent material containing coumarin skeleton and preparation method of phosphorescent material
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An organometallic iridium complex phosphorescent material containing a coumarin skeleton and a preparation method of the phosphorescent material are disclosed. The coumarin skeleton is introduced intoa traditional 2-phenylpyridine ligand, and through controlling the change of substitution positions and adopting an asymmetric structure type, double regulation and control of the luminescent wavelength and luminous efficiency of an obtained iridium complex is realized, so that the organic electrophosphorescent material having simple structure and excellent performance is obtained. By using the characteristics that the coumarin skeleton structure is highly rigid, simple, easy to synthesize, strong in luminescent property and the like, double regulation and control of the luminescent wavelength and luminous efficiency of the obtained iridium complex is realized.
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Paragraph 0110; 0117-0119
(2019/04/26)
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- Isomers of Coumarin-Based Cyclometalated Ir(III) Complexes with Easily Tuned Phosphorescent Color and Features for Highly Efficient Organic Light-Emitting Diodes
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Three Ir(CλN)2(acac)-type and one Ir(C1λN)(C2λN)(acac)-type coumarin-based cyclometalated Ir(III) complex isomers (IrC5, IrC7, IrC7-A, and IrC8) have been obtained using three coumarin-based isomers of 2-phenylpyridine (ppy)-type cyclometalating ligands (L-C5, L-C7, and L-C8). Two coordination isomers emerging as principal products (IrC7 and IrC7-A) are obtained in the synthesis of corresponding coumarin-based cyclometalated Ir(III) complexes because of two different coordination sites in ligand L-C7 to form a C-Ir bond. To the best of our knowledge, there are no such isomers reported to date. Interestingly, a broad range of phosphorescent color tuning from green (IrC8, λ = 516 nm) to red (IrC5, λ = 608 nm) has been realized through variation of the pyridyl substitution positions on the fused phenyl ring of the coumarin skeleton. In addition, based on natural transition orbital (NTO) analyses, features of the lowest triplet excited states (T1) from these coumarin-based cyclometalated Ir(III) complex isomers can be tuned easily by these ligand isomers as well. IrC5, IrC7, and IrC7-A show prevailing 3MLCT character associated with their T1 states which emit the phosphorescent signals, while the T1 state of IrC8 exhibits the dominant ligand-centered π-π? transition feature. Importantly, owing to the strong rigidity of the coumarin skeleton, all the coumarin-based cyclometalated Ir(III) complex isomers can show high phosphorescent quantum yields φp (ca. 0.4-1). Together with the improved electron-injection/electron-transport (EI/ET) ability, all the phosphorescent emitters display impressive electroluminescence (EL) performance. The device based on IrC8 gives the highest EL efficiencies of external quantum efficiency (ηext) 22.7%, current efficiency (ηL) 79.7 cd A-1, and power efficiency (ηP) 58.2 lm W-1, representing the most state-of-the-art EL ability ever achieved by coumarin-based phosphorescent emitters. All these encouraging data definitely suggest the great potential of the coumarin skeleton in both easy tuning of the photophysical properties of ppy-type Ir(III) phosphorescent complexes and developing high-performance phosphorescent emitters.
- Feng, Zhao,Yu, Yue,Yang, Xiaolong,Zhong, Daokun,Song, Dongdong,Yang, Hua,Chen, Xi,Zhou, Guijiang,Wu, Zhaoxin
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p. 7393 - 7408
(2019/06/11)
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- Dicyanovinylcoumarin as a turn-on fluorescent sensor for cyanide ion
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Dicyanovinylcoumarin chemosensors (4a, 4b and 4c) were designed and synthesized by the Knoevenagel condensation reaction. The electronic absorption and emission spectra of the dicyanovinylcoumarin isomers exhibited red shifted absorption and less emission as compared to their precursor's coumarin aldehydes. The sensing behavior of dicyanovinylcoumarin isomers were studied for different anions. In these dicyanovinylcoumarin isomers, the 7-substituted isomer shows high selectivity towards CN? in the presence of other F?, Cl?, Br?, I?, ClO4?, HSO4? and NO2? ions. The effect of CN? on the structure of dicyanovinylcoumarin isomer was studied by performing DFT calculations. The theoretical calculations show strong agreement with the experimental results. The detection limit for CN? were found to be 1.14 × 10?8 M for 7-substitued dicyanovinylcoumarin isomer 4b.
- Reddy, T. Sheshashena,Choi, Myung-Seok
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p. 108 - 114
(2017/10/25)
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- Derivatization of coumarins at the benzenoid ring in aqueous medium
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Some 6-disubstituted, 8-disubstituted, and/6,8-disubstituted compounds have been prepared from coumarin, 7-methylcoumarin, and 3,4-benzocoumarin. The Reimer-Tiemann reaction, Lederer-Manasse reaction, bromination using molecular bromine as well as 2,4,4,6-tetrabromocyclohex-2,5-dien-1-one, Elbs reaction, and diazocoupling have been carried under controlled conditions to obtain various derivatives. Further, several reactions of aldehyde derivatives of these coumarins have been carried on to prepare important functional compounds including some heterocycles. It is noteworthy that these aldehydes behave as phenolic aldehydes under alkaline conditions to undergo the Dakin reaction. The reactions are mostly carried in aqueous media involving a dianionic intermediate and hence fulfill one important criterion of green chemistry.
- Bhunia, Sankar C.,Pal, Sutanuka,Patra, Gopal C.,Pal, Sudhir C.
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p. 1679 - 1688
(2015/02/02)
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- Facile and efficient synthesis of simple coumarins via the Pd(II)/KHC03 catalyzed heck reaction under MW-Assisted neat conditions
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An efficient and fast Pd(II)-catalyzed cross-coupling of aryl halides with olefins has been developed. In the presence of Pd(OAc)2 and PdCI 2 cross-coupling of various aryl halides with olefins underwent smoothly to afford the corresponding products in moderate to high yields under MW mediated neat conditions. Simple coumarins were synthesized in good yields using 2-halophenoles in this procedure. Furthermore no solvent, solid support, expensive or/and toxic ligand is required.
- Valizadeh, Hassan,Vaghefi, Sevil
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experimental part
p. 113 - 120
(2011/06/25)
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- One-Pot wittig and knoevenagel reactions in ionic liquid as convenient methods for the synthesis of coumarin derivatives
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Efficient synthesis of a variety of 3-substituted coumarins via NaOMe-catalyzed Knoevenagel condensation and one-pot preparation of 3,4-unsubstituted coumarins in the presence of NaOMe via Wittig reaction in room-temperature ionic liquids are described. Knoevenagel condensation of 2-hydroxybenzaldehyde with dimethyl- and diethylmalonate was performed with excellent yields in room-temperature ionic liquids. Although diethyl- and dimethylchloromalonates were mostly recovered unchanged in Knoevenagel condensation, higher conversions were observed via Wittig reaction of these compounds with 2-hydroxybenzaldehyde derivatives and triphenylphosphine. Other 2-hydroxybenzaldehyde derivatives, methyl- and ethylchloroacetates, were reacted in ionic liquids to afford simple coumarins in good yields. These reactions widen the applicability of ionic liquid in organic synthesis. Copyright Taylor & Francis Group, LLC.
- Valizadeh, Hassan,Vaghefi, Sevil
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experimental part
p. 1666 - 1678
(2009/10/02)
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- Development of new pyrrolocoumarin derivatives with satisfactory fluorescent properties and notably large stokes shifts
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Small, organic, fluorescent molecules with large Stokes shifts and long emission wavelengths are ideal dyes for various modern fluorescent imaging technologies such as FRET. In this study, we designed and synthesized a number of new fluorescent molecules
- Chen, Lei,Hu, Tai-Shan,Yao, Zhu-Jun
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supporting information; scheme or table
p. 6175 - 6182
(2009/05/27)
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- ANTIBACTERIAL AGENTS
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2H-chromen-2-one derivatives useful in the treatment of bacterial infections in mammals, particularly humans, are disclosed herein.
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Page/Page column 28-29
(2008/06/13)
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- Convenient synthesis of a simple coumarin from salicylaldehyde and wittig reagent. IV: Improved synthetic method of substituted coumarins
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The reaction of salicylaldehydes (2) with Horner-Wadsworth-Emmons (HWE) or Ando-HWE reagents was attempted to afford intramolecular phosphonate derivatives (6). A new synthetic method for coumarins (1) was achieved by using protected 2.
- Takeuchi, Yasuo,Ueda, Norihiro,Uesugi, Koji,Abe, Hitoshi,Nishioka, Hiromi,Harayama, Takashi
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p. 217 - 224
(2007/10/03)
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- Convenient synthesis of a simple coumarin from salicylaldehyde and Wittig reagent. II: Synthesis of bromo- and methoxycarbonylcoumarins
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Reaction of salicylaldehydes (1) with carbethoxymethylenetriphenylphosphorane in diethylaniline under reflux gave coumarins (3) in moderate to high yield except 3-methoxycarbonylsalicylaldehyde (1e). The substituent effects are discussed. A substituent at C6 on 1 usually facilitated the formation of the coumarin ring regardless of its electronic character.
- Harayama,Nakatsuka,Nishioka,Murakami,Hayashida,Ishii
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p. 2170 - 2173
(2007/10/02)
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