- Cycloaddition vs. conjugative Michael-type addition of 2-ethoxy-3-morpholinobuta-1,3-diene with nitroolefins
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The reactivity of the title dienamine towards conjugated nitroolefins has been investigated. With 1-nitrocyclopentene carbocyclic products largely predominated, whereas with 1-nitrocyclohexene only Michael-type products were formed. The behaviour of β-nitrostyrene was found to be dependent on the reaction conditions used.
- Marc, Gasper,Nitti, Patrizia,Pitacco, Giuliana,Pizzioli, Alessandro,Valentin, Ennio
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- Role of alkyl substituents in the structure and luminescence properties of discrete terbium(III)-lithium(I) Β-Diketonates
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Functionalized perfluoroalkyl lithium β-diketonates LiL react with terbium (III) salts in methanol to give heterobimetallic complexes of general formula [(TbL3)(LiL)(MeOH)]. The length of both fluoroalkyl and hydrocarbon substituents in ligand was found to affect the crystal packing of metal complexes. Photoluminescence of heterobimetallic β-diketonates in the solid state is reported.
- Bazhin, Denis N.,Burgart, Yanina V.,Kudyakova, Yulia S.,Saloutin, Victor I.,Slepukhin, Pavel A.,Valova, Marina S.
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- Mechanistic Insights into the Triplet Sensitized Photochromism of Diarylethenes
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Operating photoswitchable molecules repetitively and reliably is crucial for most of their applications, in particular in (opto)electronic devices, and related to reversibility and fatigue resistance, which both critically depend on the photoisomerization mechanism defined by the substitution pattern. Two diarylethene photoswitches bearing biacetyl triplet sensitizers either at the periphery or at the core were investigated using both stationary as well as transient UV/Vis absorption spectroscopy ranging from the femtosecond to the microsecond time scale. The diarylethene with two biacetyl moieties at the periphery is switching predominantly from the triplet excited state, giving rise to an enhanced fatigue resistance. In contrast, the diarylethene bearing one diketone at the photoreactive inner carbon atom cyclizes from the singlet excited state and shows significantly higher quantum yields for both cyclization and cycloreversion.
- Fredrich, Sebastian,Morack, Tobias,Sliwa, Michel,Hecht, Stefan
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supporting information
p. 7672 - 7677
(2020/06/01)
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- Synthesis of 2, 6 - difluoro phenyl -1 - (4, 5 - [...]) -3 - ketone to make a new method
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The invention discloses a method for synthesizing 2, 6 - difluoro phenyl - 1 - (4, 5 - [...]) - 3 - ethyl ketone of the new method. This synthetic route avoids the synthetic intermediate 1, 3 - difluoro - 2 - steps of styrene, overcome prior art intermediate volatile not easy to store, and due to the synthetic process needs to be used sodium hydride synthesis of operation and great danger of defect, so that the synthesis process is more suitable for large-scale production; the synthetic route higher yield, and the final target 2, 6 - difluoro phenyl - 1 - (4, 5 - [...]) - 3 - ethyl ketone through re-crystallization mode is purified, high purity 98%; and this synthetic route uses the raw materials of the commercial production of the raw material, cheap and easy to obtain.
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Paragraph 0040; 0046-0049
(2019/04/14)
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- N-Heterocyclic Carbene-Catalyzed Umpolung of β,?-Unsaturated 1,2-Diketones
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The umpolung of β,?-unsaturated diketones through N-heterocyclic carbene catalysis is described, which allows access to a variety of highly functionalized bicyclic cyclohexene-β-lactones and 1,3,4-triaryl benzenes. An unprecedented reaction pattern involv
- Liu, Jian,Das, Deb Kumar,Zhang, Guoxiang,Yang, Shuang,Zhang, Hao,Fang, Xinqiang
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supporting information
p. 64 - 67
(2018/01/17)
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- Copper-Catalyzed Successive C?C bond formations on Indoles or Pyrrole: A Convergent Synthesis of Symmetric and Unsymmetric Hydroxyl Substituted N-H Carbazoles
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A novel copper-catalyzed successive C?Cbond formations on indoles and pyrrole approach for the direct synthesis of hydroxyl substituted N-H carbazoles is described. The current process represents an atom-economical method for the preparation of both symmetric and unsymmetric densely substituted and hydroxyl containing N-H carbazoles from easily accessible starting materials without the need for expensive metals and harsh reaction conditions. (Figure presented.).
- Qiao, Yu,Wu, Xin-Xing,Zhao, Yupeng,Sun, Yongqing,Li, Baoguo,Chen, Shufeng
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supporting information
p. 2138 - 2143
(2018/04/30)
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- New 3-acetylpyrazole preparation method
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The invention discloses a 3-acetylpyrazole preparation method, wherein 2,3-butanedione is used as a starting raw material, and is subjected to three steps such as carbonyl protection, enamine ketonization, and ring-closure pyrazole forming. According to the present invention, the method has characteristics of easily-available raw materials, simple operation and easily-enlarged production.
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Paragraph 0009
(2020/09/20)
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- Enantioselective intermolecular all-carbon [4+2] annulation: Via N-heterocyclic carbene organocatalysis
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The highly stereoselective intermolecular all-carbon [4+2] annulation between in situ generated acyclic dienolates and α,β-unsaturated acyl azoliums is disclosed. The identification of 2-acyloxy-3-butenones as suitable diene precursors is the key to the s
- Zhang, Guoxiang,Xu, Weici,Liu, Jian,Das, Deb Kumar,Yang, Shuang,Perveen, Saima,Zhang, Hao,Li, Xinglong,Fang, Xinqiang
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supporting information
p. 13336 - 13339
(2017/12/26)
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- Novel method for preparing 5-acetylisoxazole
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The invention discloses a novel method for preparing 5-acetylisoxazole. Starting from 2,3-butanedione, the method goes through three steps of reaction, i.e. carbonyl group protection, enamine ketonization and cyclization for isoxazole. The method disclosed by the invention has the characteristics of easy material obtainment, simplicity and convenience in operation and easiness in production expansion.
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Paragraph 0006
(2017/08/28)
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- Switching diarylethenes reliably in both directions with visible light
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A diarylethene photoswitch was covalently connected to two small triplet sensitizer moieties in a conjugated and nonconjugated fashion and the photochromic performance of the resulting compounds was investigated. In comparison with the parent diarylethene (without sensitizers) and one featuring saturated linkages, the conjugated photoswitch offers superior fatigue resistance upon visible-light excitation due to effective triplet energy transfer from the biacetyl termini to the diarylethene core. Our design makes it possible to switch diarylethenes with visible light in both directions in a highly efficient and robust fashion based on extending π-conjugation and by-product-free ring-closure via the triplet manifold. Flipping the spin: When biacetyl triplet sensitizers were linked to a dithienylethene core in a conjugated fashion, the photoswitching performance dramatically improved. This design makes it possible to switch diarylethenes with visible light in both directions in a highly efficient and robust fashion.
- Fredrich, Sebastian,G?stl, Robert,Herder, Martin,Grubert, Lutz,Hecht, Stefan
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supporting information
p. 1208 - 1212
(2016/01/20)
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- Transacetalization of Diethyl Tartrate with Acetals of α-Dicarbonyl Compounds: A Simple Access to a New Class of C2-Symmetric Auxiliaries and Ligands
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A simple access to a new class of C2-symmetric auxiliaries and ligands is based on the transacetalization of diethyl tartrate (1) with monoacetals of butane-2,3-dione in the key step.Acid-catalyzed reaction of 1 with 2 equiv of 3,3-diethoxybutan-2-one (2) gives the C2-symmetric 1,4-dioxane 7 in 88percent yield.Reduction of 7 with LiAlH4 affords the crystalline diol 9.The structure of 7 was established from the X-ray structure of 9.Dioxane 7 was converted by standard methodology into the diphosphine 24 and the TARTROL 22.Reaction of 1 with 3,3-dimethoxybutan-2-one (3) in the presence of BF3-etherate gives in analogy to the formation of 7 the 1,4-dioxane 8.This compound was transformed into the diphosphine 25 and the TARTROL 23.The trans-diaxial relationship of the methoxy groups present in 8 could be deduced without X-ray analysis from the 1H-NMR spectrum of 23.
- Berens, Ulrich,Leckel, Dieter,Oepen, Susanne C.
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p. 8204 - 8208
(2007/10/02)
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- Synthesis and Solvolyses of Cyclopropylidenealkyl Esters
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The cyclopropylidene alcohols 8a, 9a, and 10a are synthesized to study the solvolyses reactions of cyclopropylidenealkyl esters 8, 9, and 10b, f, g.The preparation of 2-cyclopropylidenecyclobutanol (10a) is achieved by Wittig reaction of its tetrahydropyr
- Hanack, Michael,Pradl, Ferdinand
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p. 777 - 793
(2007/10/02)
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