- High-selectivity preparation method for 7-methoxy-6/8-hydroxy coumarin
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The invention provides a high-selectivity preparation method for 7-methoxy-6/8-hydroxy coumarin and belongs to the field of synthesis of natural medicines. The method comprises the steps of subjecting a catechol coumarin compound to a high-selectivity methylation reaction with a methylation reagent in a proper base catalyst added organic reaction system, so as to obtain a 7-hydroxyl mono-methylate, wherein the mole ratio of a base to the catechol coumarin compound is (2.0 to 7.0): 1, the mole ratio of the methylation reagent to the catechol coumarin compound is (1.0 to 3.0): 1, the temperature of the organic reaction system is 0 DEG C to 30 DEG C, and the reaction time is 1.0 to 5.0 hours. The method has the characteristics of simplicity in operation, moderate conditions, good selectivity, high yield and the like and can be applied to the preparation of mono-methylates of coumarin catechols with different types of substituents.
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Paragraph 0036; 0037; 0038
(2017/08/28)
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- Dissociation Constants and Solubilities of Dalbergin and Nordalbergin in Different Solvents
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The dissociation constants (pKa) of dalbergin and nordalbergin were measured at 298.2 K using ultraviolet (UV) spectroscopy method. The solubilities of dalbergin and nordalbergin in water, methanol, propanone, ethyl ethanoate, trichloromethane, and hexane have been determined by the UV spectrophotometric method from 283.2 to 308.2 K at atmospheric pressure. The experimental solubility values were correlated with a modified Apelblat equation, λh model, and ideal model. The pKa value of dalbergin is 8.91 ± 0.12, and the pKa1 and pKa2 values of nordalbergin are 7.31 ± 0.29 and 9.79 ± 0.39, respectively. The solubilities of dalbergin and nordalbergin in six solvents increase with an increase in temperature. The solubility order of dalbergin in six pure solvents was trichloromethane > propanone > ethyl ethanoate > methanol > hexane > water, whereas that of nordalbergin was propanone > methanol > ethyl ethanoate > trichloromethane > water > hexane. A comparison of the solubility of dalbergin with that of nordalbergin shows that the 7-methoxyl moiety of dalbergin leads to a significantly higher solubility in trichloromethane and hexane, a little higher solubility in ethyl ethanoate, an approximately equal solubility in propanone, and a little lower solubility in methanol and water (exception 283.2 K). For dalbergin, the modified Apelblat equation shows the best correlation for all solvents, and for nordalbergin, correlation results by three models are similar.
- Kong, Wanjun,Sun, Rui,Gao, Yanjuan,Nan, Guanjun,Yang, Guangde,Li, Yiping
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p. 2585 - 2593
(2015/09/21)
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- Synthesis of 4-arylcoumarins via Cu-catalyzed hydroarylation with arylboronic acids
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(Chemical Equation Presented) In the presence of 2-4 mol % of CuOAc, methyl phenylpropiolates having a MOM-protected hydroxy group at the ortho position underwent hydroarylation with various arylboronic acids in MeOH at ambient temperature, resulting in the formation of 4-arylcoumarins in high yields after the acidic workup. This method was effectively used for the synthesis of biologically active natural and artificial compounds.
- Yamamoto, Yoshihiko,Kirai, Naohiro
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supporting information; experimental part
p. 5513 - 5516
(2009/05/27)
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- New syntheses of dalbergichromene and dalbergin from vanillin via neoflavene intermediate
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In this Letter, naturally occurring dalbergichromene and dalbergin were synthesized from a common neoflavene intermediate, which was derived from vanillin. The giving neoflavene intermediate was debenzylated with AlCl3 to yield dalbergichromene in 39% total yield, and it was oxidized by DDQ, and subsequently debenzylated by Pd(OH)2/C and cyclohexene in refluxing ethanol to give dalbergin in 31% total yield.
- Li, Sie-Rong,Chen, Liang-Yeu,Tsai, Jui-Chi,Tzeng, Jing-Yu,Tsai, Ian-Lih,Wang, Eng-Chi
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p. 2139 - 2141
(2008/02/08)
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