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Efficient Synthesis of 3-Substituted Coumarins
As ligands are versatile and confer reactivity and selectivity, various compatible combinations of ligands can be used to promote different reactions using the same metal pairs. Thus, we are interested in demonstrating the ability of ligands in multi-metal catalysis to achieve a greater range of transformations that could be developed. For example, by tuning the ligands and reaction conditions, we were able to achieve Rh/Pd-catalyzed synthesis of benzoxepines (Scheme 6, eq 1) and dihydroquinolinones (eq 2) in high enantioselectivities.
After our success in arylcyanation of -allylcarboxamides, our group searched for a broader application of this useful reaction. Adapting our method to indoles led to the dearomative -1,2-arylcyanation product, thus constructing highly substituted indoline frameworks which have desirable biological activity. As seen in the reaction below, these rigid products are highly functionalized. The indoline core contains a tetrasubstituted tertiary carbon, a functionalizable acidic alpha proton, and a highly versatile nitrile group. Additionally, these scaffolds are synthesized in high yield and diastereoselectivity.
Efficient Synthesis of 3-Substituted Coumarins.
Pareek A. K, Joseph P. E, Daya S. S. An Efficient Synthesis, Characterization of some Novel 6 -(R) phenyl-azo-coumarin -3- carboxy(3-chloro- 4-methoxy) anilide and 2- hydroxy- 5(R)-phenyl - azo - benzylidine (3- chloro - 4 -methoxy)aniline and their Antibacterial Activity. Biomed Pharmacol J 2010;3(1). Available from:
Pareek A. K, Joseph P. E, Daya S. S. An Efficient Synthesis, Characterization of some Novel 6 -(R) phenyl-azo-coumarin -3- carboxy(3-chloro- 4-methoxy) anilide and 2- hydroxy- 5(R)-phenyl - azo - benzylidine (3- chloro - 4 -methoxy)aniline and their Antibacterial Activity. Biomed Pharmacol J 2010;3(1)
Synthesis of Coumarins - Organic chemistry
The use of multiple catalysts in a reaction vessel in organic synthesis has recently gained significant interest, as multi-catalytic systems can achieve superior reactivity and synthetic efficiency that are unmatched with single catalytic systems. Important advantages include new modes of substrate activation, new bond forming transformations, and efficient complexity generation processes that lead to waste reduction in synthesis and minimized environmental impact (Scheme 1). For example, the use of multiple metals in catalysis has provided powerful transformations such as the Wacker process and the Sonogashira cross coupling. Thus, in comparison to the traditional approach of using a single metal catalyst to perform a reaction, taking the multi-metal catalysis approach toward synthesis can be highly effective.
For example, synthesis of hydrocarbons is widespread in cyanobacteria (., PLoS One 2014, 9:e85140), and it is thought that cyanobacterial alka(e)nes contribute significantly to the hydrocarbon cycle of the upper ocean.
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Oxygen - Organic Chemistry Portal
(2010) Efficient synthesis of 1,4-disubstituted polyfunctional piperazines a sequential one-pot Ugi/nucleophilic addition five-component reaction, 3277-3279.
PDF Downloads : Oriental Journal of Chemistry
Among these compounds, echinenone and canthaxantin are abundant in cyanobacteria are characteristic of cyanobacteria ().
Violaxanthin is an epoxidized derivative of antheraxanthin (hydroxylated cryptoxanthin) and forms with zeaxanthin the xanthophyll cycle that is said to protect the photosynthetic system of plants against damage by excess light.
Rhodium-Catalyzed Asymmetric 1,4-Addition and Its …
(2009) Efficient synthesis of pyrano[2,3-c]coumarins via intramolecular domino Knoevenagel hetero-Diels�Alder reactions. 65: 4228-4234.
He graduated from Kyoto University in 1970
In conclusion, we have found that the reaction of ethyl acetoacetate and substituted phenols leads to an efficient synthesis of substituted 4-methylcoumarins in good to very high yields within relatively short reaction times using silica-supported ZnCl2 as a simple and reusable heterogeneous catalyst. The reaction is simple, mild, and convenient and is environment friendly.
Bioorganic & Medicinal Chemistry Letters | Vol 20, Iss …
Silica-ZnCl2 has been found to be an efficient and eco-friendly catalyst for the synthesis of substituted 4-methylcoumarins from ethyl acetoacetate and substituted phenols under “neat” conditions in an oil bath at 80°C. The experimental procedure is simple, includes shorter reaction times (15–65min), compatible with sensitive functional groups, and results in excellent yield of the products.
Molecules | October 2017 - Browse Articles
Many of the synthetic, semi-synthetic, natural molecules containing the coumarin scaffold and included simple coumarin, azo-coumarin, pyrano-coumarin, iso-coumarin, benzo-coumarin have become an important class of heterocyclic compounds in drug research. Azo-coumarin have been reported to have multiple biological activities 1, some azo-coumarin and their derivatives have been reported to possess anti-coagulant2, antibacterial3, antifungal4, antiallergic5, antidiabe-tic6, analgesic7, activities. Azo-schiff’s bases are also important class of heterocyclic compounds and had got wide applications in pharmacology and industrial fields8. Some substituted azo-schiff’s bases and their derivatives have also been reported to possesses antiviral9, anticancer 10, antibacterial11, activities. In this laboratory also a number of substituted azo-coumarins and azo-schiff’s bases and their derivatives have been prepared by various workers12-15.
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