- Synthesis of Kainoids and C4 Derivatives
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A unified stereoselective synthesis of 4-substituted kainoids is reported. Four kainic acid analogues were obtained in 8-11 steps with up to 54% overall yields. Starting from trans-4-hydroxy-l-proline, the sequence enables a late-stage modification of C4 substituents with sp2 nucleophiles. Stereoselective steps include a cerium-promoted nucleophilic addition and a palladium-catalyzed reduction. A 10-step route to acid 21a was also established to enable ready functionalization of the C4 position.
- Tian, Zhenlin,Menard, Frederic
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p. 6162 - 6170
(2018/05/23)
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- Synthesis method of high-purity 9-bromine-9-benzofiurene
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The invention discloses a synthesis method of high-purity 9-bromine-9-benzofiurene. The synthesis method is characterized by comprising the following steps: dissolving 9-phenyl-9-fluorenol into an organic solvent; adding an HBr solution, wherein the reaction liquid is yellowish and turbid; reacting and ripening through a water bath, wherein the color of the solution gradually deepens and is pale brown and turbid; cooling the reaction liquid to the room temperature, washing an organic phase with saturated sodium carbonate and the like, sequentially implementing the steps like drying with magnesium sulfate to obtain a crude product, namely 9-bromine-9-benzofiurene; heating the crude product, namely 9-bromine-9-benzofiurene, through the organic solvent, refluxing, dissolving, adding activatedcarbon to decolourize, and sequentially implementing the steps like thermally filtering to obtain a white powder crystal, namely 9-bromine-9-benzofiurene. The raw materials adopted for synthesis arecheap, easy to get, and are industrial products, the reaction condition is mild, the risk is low, the operation is convenient, the reaction is easy to control, and the yield is up to more than 80%, sothat the synthesis method is suitable for industrial production; the synthesis method only needs recrystallization once, and the product purity is up tp more than 99%.
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Paragraph 0022; 0023; 0024; 0025; 0026; 0027; 0028-0032
(2018/03/26)
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- Fluorene-based organic compound and application thereof on OLED device
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The invention relates to a fluorene-based organic compound and application thereof on an OLED device. A structure of the compound is that fluorine is connected with a hexatomic ring structure of a benzo hexatomic ring through a carbon-carbon bond, so that material chemical stability is improved and active positions of a branch chain radical are prevented from being exposed through the carbon-carbon bond connection; the whole molecule is a relatively great rigid structure, and has relatively high triplet-state energy level (T1); moreover, steric hindrance is great, rotation is not liable to occur and the three-dimensional space structure is more stable, so that the compound has a relatively high glass transition temperature and relatively high molecule thermal stability; besides, distribution positions of HOMO and LUMO of the compound are separated from each other, so that the fluorene-based organic compound has proper HOMO and LUMO energy level; and after the compound is applied to theOLED device, light-emitting efficiency of the device can be effectively improved, and the service life of the device can be effectively prolonged.
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Paragraph 0062; 0066; 0067
(2018/03/26)
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- Organic compound with fluorene as nucleus and application of same to OLED device
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The invention relates to an organic compound with fluorene as a nucleus and application of the same to an OLED device. The compound is such structured that fluorine is connected with a benzo six-membered ring via a C-C bond; connection via the C-C bond is beneficial for improving the chemical stability of the compound and preventing active positions of branched groups from exposure; the whole molecule is of a large rigid structure, has a high triplet-state energy level (T1) and is large in steric hindrance and not prone to rotation, so the three-dimensional spatial structure of the compound is more stable; and thus, the compound has a high glass transition temperature and molecular heat stability. Moreover, the HOMO and LUMO of the compound are distributed at different positions, so the compound has appropriate HOMO and LUMO energy levels. Thus, the compound can effectively improve the luminescence efficiency and service life of the OLED device when applied to the device.
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Paragraph 0050; 0051; 0054
(2017/12/06)
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- Alkyl substituent effects on pipecolyl amide isomer equilibrium: Efficient methodology for synthesizing enantiopure 6-alkylpipecolic acids and conformational analysis of their N-acetyl N'-methylamides
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Enantiopure 6-alkylpipecolic acid hydrochlorides 1a-e were synthesized in five steps and 15-59% overall yields from α-tert-butyl β-methyl N- (PhF)aspartate (3) via an approach featuring selective hydride reduction to the corresponding aspartate β-aldehyde 2, aldol condensations with the enolates of various methyl alkyl ketones, and diastereoselective intramolecular reductive aminations. The influence of the 6-position substituent on the equilibrium and the energy barrier for isomerization of the amide N-terminal to pipecolate was then explored via the synthesis of N- acetyl N'-methylpipecolinamide (16) and its (2S,6R)-6-tert- butylpipecolinamide counterpart 17, and their conformational analysis by proton NMR spectroscopy and coalescence experiments. The presence of the tert-butyl substituent augmented the population of the amide cis-isomer and lowered the barrier for pipecolyl amide isomerization in water. Compared with the results from our previous examination of N-acetyl-5-tert-butylproline N'- methylamides (Beausoleil, E.; Lubell, W. D. J. Am. Chem. Soc. 1996, 118, 12902), the consequences of the bulky 6-alkyl substituent on the acetamide geometry and isomerization barrier were less pronounced in the pipecolate series relative to the respective proline amides.
- Swarbrick, Martin E.,Gosselin, Francis,Lubell, William D.
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p. 1993 - 2002
(2007/10/03)
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- Reactivities of 9-Arylfluoren-9-yl and 1-(4-Dimethylaminophenyl)ethyl Cations in Water and Trifluoromethanol Studied by Laser Flash Photolysis
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9-Arylfluoren-9-yl cations have been observed as transient intermediates upon 248 nm laser photolysis of 9-arylfluoren-9-ols in 2,2,2-trifluoroethanol (TFE) and 1:4 (v/v) acetonitrile-water.Quantum yields for the formation of the cations were measured and found to lie in the range 0.5-0.8.Rate constants for the decay of the cations in the two solvents parallel each other, a plot of log kTFE versus log kw being linear with a slope of 1.00.These rate constants are approximately two orders of magnitude larger than those observed in the same solvent for the corresponding monosubstituted triarylmethyl cations.Substituent effects in the two series are similar.For both the hydration reaction and the overall equilibrium, a two-parameter treatment dissecting the substituent contributions into resonance and polar effects shows that the former are more important in the triarylmethyl series, while the latter are more important in the fluorenyl series.Twisting of the 9-aryl ring out of coplanarity with the fluorenyl ring is the likely cause of the diminished resonance interaction in this system.The 1-(4-dimethylaminophenyl)ethyl cation has been observed in TFE and 1:1 TFE-W, being generated by photoprotonation of 4-dimethylaminostyrene.Rate constants for decay are about 50 times smaller than those previously estimated by a clock method.The failure of the latter approach is associated with the rate constant for the clock nucleophile becoming significantly less than diffusion control for this highly stable cation.An extended log kw-pKR correlation is constructed.This shows a series of reasonably parallel lines associated with different families.In considering cations with the same pKR, the order of inherent reactivity is 9-unsubstituted-9-xanthylium ca. cyclic dialkoxy-carbocation > phenyltropylium > diarylmethyl ca. 9-arylxanthylium > triarylmethyl ca. 9-arylfluoren-9-yl.The log kw-pKR data for each family are reasonably satisfied by a linear relationship, with a slope d(log kw)/dpKR of 0.6+/-0.1.The triarylmethyl and 9-arylfluoren-9-yl cations form a contiguous series covering 26 pKR units.The data for these indicate that there is probably a gentle downward curvature in the correlation, particularly at the high reactivity end.This is consistent with a Hammond effect on the transition state such that it becomes more cation-like in the hydration direction for more reactive cations.
- Cozens, Frances L.,Mathivanan, N.,McClelland, Robert A.,Steenken, Steen
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p. 2083 - 2090
(2007/10/02)
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