- Ionic Liquids with Multi-Active Sites Synergistically Catalyzed Metal-Free Transformation of Alcohols Using Dimethyl Carbonate as an Environmental Solvent
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One of the ultimate goals in organic synthesis is to develop metal-free, efficient and easily separable catalytic system for atom economic organic reactions in an environmental solvent. Direct substitution reaction of alcohols and hydrocarbon compounds is a significant and atom economic method for C?C bond formation. Herein, a metal-free and efficient catalytic system including recyclable pyridine-based ionic liquids with multiple active sites as the catalyst and dimethyl carbonate as the environmentally friendly solvent was developed for atom economic C3 substitution of 4-hydroxycoumarins with alcohols. Primary aromatic alcohols, secondary aliphatic and aromatic alcohols were suitable for the reaction, providing up to 99 % yield. The catalytic system could be easily scaled up to gram-scale with nearly quantitative yield. Coumatetralyl as commercial rodenticide could be prepared directly from commercially available 4-hydroxycoumarin and 1,2,3,4-tetrahydronaphthalen-1-ol. Racemic product derived from the reaction of (R)-1-phenylethanol and 4-hydroxycoumarin indicated the reaction was achieved through an SN1 pathway. The comparison of the activities and acidities of the ionic liquids demonstrated that there was no directly relationship between them. Control experiments showed that the reaction probably proceeded via carbocation, ether intermediate and synergistically promoted effect of hydrogen bonding between the ionic liquid with multi-active sites and substrates.
- Li, Zengmin,Wen, Yating,Wang, Ning,Han, Feng,Li, Ying,Zhuang, Hongfeng,Miao, Chengxia
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p. 3819 - 3826
(2021/08/24)
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- HFIP Promoted C3 Alkylation of Lawsone and 4-Hydroxycoumarin with Alcohols by Dehydrative Cross-Coupling
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An environmentally benign system for the direct alkylation of lawsones and 4-hydroxycoumarins with alcohols in 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) is reported. The reaction proceeded smoothly via a dehydrative cross-coupling process by utilizing the unique properties of HFIP. A variety of alkylated products and subsequent one-pot cyclized products (pyranonaphthoquinones and pyranocoumarins) could be obtained in 40-93% yields.
- Chen, Yixin,Wang, Yurong,Zhong, Rong,Li, Jinshan
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p. 10638 - 10647
(2020/09/23)
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- Alkylation of 1,3-dicarbonyl compounds with benzylic and propargylic alcohols using Ir-Sn bimetallic catalyst: Synthesis of fully decorated furans and pyrroles
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The heterobimetallic complex [Ir(COD)(SnCl3)Cl(μ-Cl)] 2 catalyzes the direct substitution of hydroxyl groups in benzylic and propargylic alcohols by 1,3-dicarbonyl moiety. In 4-hydroxycoumarin, benzylation and propargylation occurs at the 3-position. Selective propargylation or allenylation takes place depending on the nature of propargylic alcohol. By applying the methodology, multi-substituted furans and pyrroles have been synthesized in good yields.
- Chatterjee, Paresh Nath,Roy, Sujit
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experimental part
p. 4569 - 4577
(2011/07/08)
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- Direct catalytic benzylation of hydroxycoumarin - Efficient synthesis of warfarin derivatives and analogues
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Effective metal-catalyzed benzylations of 4-hydroxycoumarin have been developed. Employing a low amount of a cheap, nontoxic, and air-stable catalyst the 3-alkylated hydroxycoumarins were isolated in high yields after short reaction times. Applying this new methodology two widely used anticoagulants phenprocoumon and coumatetralyl were synthesized applying mild reaction conditions. Georg Thieme Verlag Stuttgart New York.
- Rueping, Magnus,Nachtsheim, Boris J.,Sugiono, Erli
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experimental part
p. 1549 - 1553
(2010/08/22)
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- Fe(ClO4)3·×H2O-Catalyzed direct C-C bond forming reactions between secondary benzylic alcohols with different types of nucleophiles
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Fe(ClO4)3·×H2O as a highly effective catalyst for benzylation of 1,3-dikones, β-ketoesters, 1,3-diesters, electron-rich arenes and heteroarenes and 4-hydroxycoumarin with various benzylic alcohols is described. The usefulness of this procedure is shown by a synthesis of bis-symmetrical triarylmethanes and one step synthesis of an anti-coagulant compound 4-hydroxy-3-(1,2,3,4-tetrahydronaphthalen-1-yl)-2H-chromen-2-one (Coumatetralyl (B)). The advantages of this protocol are broad scope, mild conditions, use of inexpensive catalyst and simplicity of operation since water is the only side product.
- Thirupathi, Ponnaboina,Kim, Sung Soo
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experimental part
p. 2995 - 3003
(2010/06/14)
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- Solid-supported acid-catalyzed C3-alkylation of 4-hydroxycoumarins with secondary benzyl alcohols: access to 3,4-disubstituted coumarins via Pd-coupling
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An efficient and operationally simple method for C3-alkylation of 4-hydroxycoumarins has been developed under acidic medium giving good yields of the products. In the present method, a reusable Amberlite IR-120 (H+ form) was used as an acid catalyst and secondary benzyl alcohols were used as alkylating agents. The obtained 3-alkylated-4-hydroxycoumarins offered an easy access for the synthesis of 3,4-disubstituted coumarins by way of Pd-catalyzed coupling reactions.
- Reddy, Ch. Raji,Srikanth,Narsimha Rao,Shin, Dong-Soo
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experimental part
p. 11666 - 11672
(2009/04/11)
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- Oil-in-water emulsions, and their use
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Novel oil-in-water emulsions, which contain (a) 0.1 to 80% by weight of at least one sparingly water-soluble active compound (as herein defined) selected from agrochemical active compounds, active compounds for combating pests in the domestic field and hygiene field and/or pharmacologically active compounds, (b) 1 to 20% by weight of at least one alkylaryl polyglycol ether of the general formula STR1 wherein R1 represents a hydrogen atom or an alkyl group having 1 to 16 carbon atoms, R3 represents a hydrogen atom or a methyl group, m is 1, 2 or 3, and n is an integer from 10 to 50, if appropriate in a mixture with an alkylarylsulphonic acid salt of the general formula STR2 wherein R3 represents an alkyl group having 8 to 35 carbon atoms and Me≈ represents an alkali metal cation, an equivalent of an alkaline earth metal cation or a cation of the general formula STR3 wherein R', R", R'" and RIV independently of one another represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a hydroxyalkyl group having 1 to 4 carbon atoms, (c) water, (d) if necessary, 1 to 30% by weight of at least one poorly water-miscible organic solvent and/or a solubilizer, and (e) if appropriate 0.05 to 15% by weight of one or more additives, the sum of the components being 100% by weight in each case, a process for the preparation of these emulsions and their use in the field appropriate to the active compound.
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