- Sustainable Synthesis of the Naturally Hypolipidemic Agent α-Asarone
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(Chemical Equation Presented). A short and practical preparation of α-asarone was developed using the inexpensive methylisoeugenol as a starting material. The utilization of a sequence of tribromination, debromination, and copper-mediated aromatic substitution enabled the stereoselective formation of only the E-isomer of α-asarone in good yield.
- Camacho-Dávila, Alejandro A.,Chávez-Flores, David,Zaragoza-Galán, Gerardo,Ramos-Sánchez, Víctor H.
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- Photoacid-Enabled Synthesis of Indanes via Formal [3 + 2] Cycloaddition of Benzyl Alcohols with Olefins
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An environmentally friendly and highly diastereoselective method for synthesizing indanes has been developed via a metastable-state photoacid system containing catalytic protonated merocyanine (MEH). Under visible-light irradiation, MEH yields a metastable spiro structure and liberated protons, which facilitates the formation of carbocations from benzyl alcohols, thus delivering diverse molecules in the presence of various nucleophiles. Mainly, a variety of indanes could be easily obtained from benzyl alcohols and olefins, and water is the only byproduct.
- Yang, Biao,Dong, Kui,Li, Xiang-Sheng,Wu, Li-Zhu,Liu, Qiang
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supporting information
p. 2040 - 2044
(2022/03/17)
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- A donor-acceptor complex enables the synthesis of: E -olefins from alcohols, amines and carboxylic acids
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Olefins are prevalent substrates and functionalities. The synthesis of olefins from readily available starting materials such as alcohols, amines and carboxylic acids is of great significance to address the sustainability concerns in organic synthesis. Metallaphotoredox-catalyzed defunctionalizations were reported to achieve such transformations under mild conditions. However, all these valuable strategies require a transition metal catalyst, a ligand or an expensive photocatalyst, with the challenges of controlling the region- and stereoselectivities remaining. Herein, we present a fundamentally distinct strategy enabled by electron donor-acceptor (EDA) complexes, for the selective synthesis of olefins from these simple and easily available starting materials. The conversions took place via photoactivation of the EDA complexes of the activated substrates with alkali salts, followed by hydrogen atom elimination from in situ generated alkyl radicals. This method is operationally simple and straightforward and free of photocatalysts and transition-metals, and shows high regio- and stereoselectivities.
- Chen, Kun-Quan,Shen, Jie,Wang, Zhi-Xiang,Chen, Xiang-Yu
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p. 6684 - 6690
(2021/05/31)
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- Cobalt-Catalyzed Z to e Isomerization of Alkenes: An Approach to (E)-β-Substituted Styrenes
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An efficient cobalt-catalyzed Z to E isomerization of β-substituted styrenes using the amido-diphosphine ligand was developed, delivering the (E)-isomers with good functional tolerance and high stereoselectivity. The reaction could be scaled up to gram-scale with a catalyst loading of 0.1 mol %, using a mixture of (Z)- and (E)-alkene as the starting material. Preliminary mechanistic studies indicated that cobalt(I)-hydride and a benzylic-cobalt species were probably involved in the reaction, as supported by experiments and DFT calculations.
- Liu, Hongmei,Xu, Man,Cai, Cheng,Chen, Jianhui,Gu, Yugui,Xia, Yuanzhi
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p. 1193 - 1198
(2020/02/04)
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- Green and simple preparation process of alpha-asarone
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The invention relates to the technical field of medicine, in particular to a green and simple preparation process of alpha-asarone. 1,2,4-trimethoxybenzene is adopted as a raw material, and three steps, namely, an acylation reaction, a reduction reaction and a dehydration reaction are included. Through the preparation process of alpha-asarone, the total yield can reach 62.3% or above, all organicsolvents can be recycled repeatedly, and the process has the advantages of low cost, small pollution, safe and convenient operation, high yield and the like.
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Paragraph 0044; 0051-0053; 0054; 0061-0063
(2019/10/01)
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- Preparation and purification method α . (by machine translation)
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The invention relates to the technical field of medicine . The α - asarum is a preparation and purification method. (1) The following steps: (2) adding the cis-trans α / β-asarine mixture into an organic solvent, adding a stabilizer to reflux the water, distilling off the solvent; and distilling, in step 1, rectifying the solvent and continuously discharging trace nitrogen, respectively, into the rectification material in a reduced-pressure rectification process to collect the distillation head, respectively. Main fraction, distillate; (3) Step 2, the distilled main fraction is added with a solvent chromatography, and the precipitate is crystallized under nitrogen with anhydrous methanol or petroleum ether to yield a high purity α - asarone powder product. In addition, the method is easy and convenient to operate, the raw material cost is 98% low, α -asarum yield 0.62% is high, and industrial mass production is easy to realize. α - asarone. (by machine translation)
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Paragraph 0047-0058
(2019/09/13)
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- Synthetic process of alpha-asarone
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The invention belongs to the technical field of medicine and concretely relates to a synthetic process of alpha-asarone. In the dehydration elimination reaction stage of the synthetic process of alpha-asarone, propionic anhydride, anhydrous propionic acid or the mixed solution of propionic acid and propionic anhydride is selected as a dehydrating agent. The molar mass ratio of 2,4,5-trimethoxybenzene propyl alcohol to the dehydrating agent is 1:(0.1-20). Anhydrous sodium propionate or anhydrous potassium propionate is a dehydration catalyst. The molar mass ratio of 2,4,5-trimethoxybenzene propyl alcohol to the catalyst is 1:(0.1-2). The process provided by the invention can greatly improve the yield of alpha-asarone and inhibit the formation of beta-asarone and the formation of impuritiessuch as asarone polymers, and reduce the cost. The synthetic process is suitable for industrial production of alpha-asarone.
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Paragraph 0033; 0036; 0037; 0041; 0042
(2018/11/22)
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- Larvicidal and structure-activity studies of natural phenylpropanoids and their semisynthetic derivatives against the tobacco armyworm Spodoptera litura (Fab.) (Lepidoptera: Noctuidae)
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The larvicidal activity of 18 phenylpropanoids, 1-18, including phenylpropenoate, phenylpropenal, phenylpropene, and their semisynthetic analogues, were evaluated against the tobacco armyworm, Spodoptera litura (FAB.), to identify promising structures with insecticidal activity. Amongst various phenylpropanoids, isosafrole, a phenylpropene, showed the best activity, with an LC50 value of 0.6 μg/leaf cm2, followed by its hydrogenated derivative dihydrosafrole (LC50=2.7 μg/leaf cm 2). The overall larvicidal activity of various phenylpropene derivatives was observed in the following order: isosafrole (6) >dihydrosafrole (16)>safrole (12)>anethole (4)>methyl eugenol (11)>eugenol (13)>β-asarone (8)>dihydroasarone (18)>dihydroanethole (15). Dihydrosafrole might be a promising compound, although presenting a lower larvicidal activity than isosafrole, because of its better stability and resistance to oxidative degradation (due to the removal of the extremely reactive olefinic bond) in comparison to isosafrole. Such structure-activity relationship studies promote the identification of lead structures from natural sources for the development of larvicidal products against S. litura and related insect pests.
- Bhardwaj, Anu,Tewary, Dhananjay Kumar,Kumar, Rakesh,Kumar, Vinod,Sinha, Arun Kumar,Shanker, Adarsh
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experimental part
p. 168 - 177
(2010/04/29)
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- Role of the methoxy group in product formation via TiCl 4 promoted 4-phenyldioxolane isomerizations
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The product distribution obtained from the TiCl 4 initiated intramolecular isomerizations of 4-methoxyphenyl-and trimethoxyphenyldioxolanes at -78 °C, -30 °C and 0 °C provided insights into the important regiochemical role played by these groups in such Mukaiyama-type rearrangements through their resonance effects on the aryl ring of the dioxolanes. ARKAT USA, Inc.
- Green, Ivan R.,October, Natasha
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experimental part
p. 71 - 96
(2010/07/20)
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- Neutral ionic liquid [hmim]Br as a green reagent and solvent for the mild and efficient dehydration of benzyl alcohols into (E)-arylalkenes under microwave irradiation
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A mild and efficient, ionic-liquid-assisted, green protocol for the dehydration of benzyl alcohols into the corresponding (E)-arylalkenes under microwave irradiation has been developed. The method utilizes a neutral and recyclable ionic liquid (1-hexyl-3-methylimidazolium bromide) as a reagent and solvent to cleanly provide a wide range of olefins without the need of harsh and expensive Bronsted/Lewis acids. The method was extended to the efficient conversion of acetylated/benzoylated derivatives of benzyl alcohol into their corresponding (E)-arylalkenes. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Kumar, Rakesh,Sharma, Abhishek,Sharma, Naina,Kumar, Vinod,Sinha, Arun K.
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supporting information; experimental part
p. 5577 - 5582
(2009/05/11)
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- Ultrasound-assisted convenient synthesis of hypolipidemic active natural methoxylated (E)-arylalkenes and arylalkanones
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An ultrasound-assisted convenient method was developed for the conversion of toxic methoxylated cis-isomer of arylalkenes into its hypolipidemic active trans-isomer. Treatment of cis-isomer or mixture of all three isomers (1a-1j) with ammonium formate and 10% Pd/C gave arylalkanes (2a-2j), which upon oxidation with DDQ in anhydrous dioxane containing a little amount of silica gel, provided (E)-arylalkenes (3a-3g) in 42-72% yield depending upon the substituents attached at the aryl ring. The same method, upon addition of a few drops of water, provided hypolipidemic active arylalkanones (3h-3j) in 59-65% yield.
- Joshi, Bhupendra P.,Sharma, Anuj,Sinha, Arun K.
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p. 3075 - 3080
(2007/10/03)
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- An effective system to synthesize hypolipidemic active α-asarone and related methoxylated (E)-arylalkenes
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Methoxylated (E)-arylalkenes (1a-1k) were prepared in two steps by an improved Grignard reaction comprising the reverse addition of alkylmagnesium bromide to benzaldehydes (2a-2k) in anhydrous ether and toluene into arylalkanols (3a-3k) in high yield, followed by dehydration with silica gel under microwave irradiation for 3-12 min, depending upon the substituents attached to the aromatic ring to afford hypolipidemic active α-asarone (1a) and related methoxylated (E)-arylalkenes (1b-1k).
- Sharma, Anuj,Joshi, Bhupendra P.,Sinha, Arun K.
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p. 2231 - 2235
(2007/10/03)
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- A PROCESS FOR THE PREPARATION OF PHARMACOLOGICALLY ACTIVE ALPHA-ASARONE FROM TOXIC BETA-ASARONE RICH ACORUS CALAMUS OIL
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The present invention relates to a process for the preparation of high purity and yield α-asarone, trans 2,4,5-trimethoxy cinnamaldehyde, 2,4,5-trimethoxy-phenyl propionone, from β-asarone or β-asarone rich Acorus calamus oil containing α and γ-asarone by hydrogenating, followed by treatment with DDQ with or without solid support of silica gel or alumina in dry organic solvent and α-asarone can also be obtained by treating the hydrogenated product of β-asarone or β-asarone rich Acorus calamus with DDQ in an aqueous organic solvent to obtain an intermediate 2,4,5-trimethoxy phenyl propionone, which in turn is reduced with sodiumborohydride to obtain the corresponding 2,4,5-trimethoxy-phenyl propanol and followed by final treatment with a dehydrating agent.
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Page/Page column 23
(2008/06/13)
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- Process for the preparation of pharmacologically active α-asarone from toxic β-asarone rich acorus calamus oil
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The present invention relates to a process for the preparation of high purity and yield α-asarone, trans 2,4,5-trimethoxy cinnamaldehyde, 2,4,5-trimethoxy-phenyl propionone, from β-asarone or β-asarone rich Acorus calamus oil containing α and γ-asarone by hydrogenating, followed by treatment with DDQ with or without solid support of silica gel or alumina in dry organic solvent and α-asarone can also be obtained by treating the hydrogenated product of β-asarone or β-asarone rich Acorus calamus with DDQ in an aqueous organic solvent to obtain an intermediate 2,4,5-trimethoxy phenyl propionone, which in turn is reduced with sodiumborohydride to obtain the corresponding 2,4,5-trimethoxy-phenyl propanol and followed by final treatment with a dehydrating agent.
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- Photooxidation of β-Asarone
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Exposure of β-cis-asarone (1) as neat oil to sunlight for a month gives five photoproducts characterised as β-trans-asarone (2), (E)-(3)- and (Z)-(4)-3-(2,4,5-trimethoxyphenyl)-propen-2-als, asaraldehyde (5) and acoradin (6).All the products have been identified on the basis of their spectral data.A reaction mechanism leading to the formation of photoproducts is suggested.
- Saxena, D. B.,Mukerjee, S. K.
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p. 683 - 684
(2007/10/02)
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