Visible-light promoted oxidative cyclization of cinnamic acid derivatives using xanthone as the photocatalyst
作者:Bin Zhao、Bo Xu
DOI:10.1039/d0ob02417a
日期:——
coumarin derivatives via a tandem double bond isomerization/oxidative cyclization of cinnamic acids. Inexpensive and stable xanthone was used as the photocatalyst, and readily available Selectfluor was used as the oxidant. This method tolerates a wide range of functional groups and offers excellent chemical yields in general. Besides, the photocatalytic oxidative cyclization of cinnamic acid esters gives
Peroxodisulfate-assisted three-component benzylation of coumarins with styrenes and KSCN: a transition-metal-free approach for the synthesis of 3-(1-aryl-2-thiocyanatoethyl)-2<i>H</i>-chromen-2-one in ethyl lactate
作者:Palani Natarajan、Priya、Deachen Chuskit
DOI:10.1039/d1gc01382c
日期:——
Peroxodisulfate-assisted three-component benzylation of coumarins with styrenes and KSCN to 3-(1-aryl-2-thiocyanatoethyl)-2H-chromen-2-one is reported for the first time. This reaction proceeds via the consecutive addition of the SCN radical to styrenes followed by the addition of the resultant substituted-benzylic radical to the C3-position of coumarin derivatives. In contrast to previous approaches
首次报道了过二硫酸盐辅助香豆素与苯乙烯和 KSCN 的三组分苄基化反应生成 3-(1-aryl-2-thiocyanatoethyl)-2 H -chromen-2-one。该反应通过将 SCN 基团连续加成到苯乙烯上,然后将得到的取代苄基基团加成到香豆素衍生物的 C 3位进行。与以前通常需要过渡金属催化、有毒的挥发性有机溶剂、碱和高温的方法相比,香豆素的苄基化策略是无过渡金属和无碱的,并且在环境条件下适用于乳酸乙酯作为一种绿色介质。
Transition Metal-Free Oxidative Cross-Coupling C(<i>sp</i>
<sup>2</sup>
)-C(<i>sp</i>
<sup>3</sup>
) Bond Formation: Regioselective C-3 Alkylation of Coumarins with Tertiary Amines
作者:Longyang Dian、Daisy Zhang-Negrerie、Yunfei Du
DOI:10.1002/adsc.201700521
日期:2017.9.18
A novel transition‐metal‐free regioselective C‐3 alkylation of coumarins was realized under mild reaction conditions. Various coumarins and tertiary amines smoothly underwent direct C(sp2)–C(sp3) bond formation in the presence of (n‐Bu)4NI as the catalyst and t‐BuOOH as the oxidant.
6-Oxo-7-substituted -6H-indeno-[5,4-b]furan(and thiophene)carboxylic acids; the 1,2,7,8-tetrahydro; 7,8-dihydro; and 1,2-dihydro derivatives; and the salt, ester and amide derivatives thereof are disclosed having diuretic-saluretic and antihypertensive activity.
Cobalt-Catalyzed Twofold Direct C(<i>sp</i>
<sup>2</sup>
)−C(<i>sp</i>
<sup>3</sup>
) Bond Coupling: Regioselective C-3 Alkylation of Coumarins with (Cyclo)alkyl Ethers
作者:Longyang Dian、Hui Zhao、Daisy Zhang-Negrerie、Yunfei Du
DOI:10.1002/adsc.201600349
日期:2016.7.28
A cobalt‐catalyzed regioselective C‐3 alkylation of coumarins was realized under mild reaction conditions, during which a variety of substituted coumarins including those containing sensitive functional groups could smoothly undergo the selective C(sp2)−C(sp3) bond formation with a series of cyclic or straight‐chain alkyl ethers.