One-pot preparation of 4-aryl-3-bromocoumarins from 4-aryl-2-propynoic acids with diaryliodonium salts, TBAB, and Na<sub>2</sub>S<sub>2</sub>O<sub>8</sub>
作者:Teppei Sasaki、Katsuhiko Moriyama、Hideo Togo
DOI:10.3762/bjoc.14.22
日期:——
Various 4-aryl-3-bromocoumarins were smoothly obtained in moderate yields in one pot by treating 3-aryl-2-propynoic acids with diaryliodonium triflates and K2CO3 in the presence of CuCl, followed by the reaction with tetrabutylammonium bromide (TBAB) and Na2S2O8. The obtained 3-bromo-4-phenylcoumarin was transformed into 4-phenylcoumarin derivatives bearing C-H, C-S, C-N, and C-C bonds at 3-position
We herein establish a multicomponent annulation method for the synthesis of valuable iminocoumarins using aryl thiocarbamates, internal alkynes, and sulfonamides as starting materials, which are safe and readily available. The key step is a Rh-catalyzed and sulfur-directed C—H bondactivation. Preliminary mechanistic investigations suggested that the nucleophilic attack of the sulfonamide on an active
Palladium-Catalyzed Carbonylative Annulation of Internal Alkynes: Synthesis of 3,4-Disubstituted Coumarins
作者:Dmitry V. Kadnikov、Richard C. Larock
DOI:10.1021/jo0350763
日期:2003.11.1
The palladium-catalyzedannulation of internalalkynes by o-iodophenols in the presence of CO results in exclusive formation of coumarins. No isomeric chromones have been observed. The best reaction conditions utilize the 2-iodophenol, 5 equiv of alkyne, 1 atm of CO, 5 mol % Pd(OAc)2, 2 equiv of pyridine, and 1 equiv of n-Bu4NCl in DMF at 120 degrees C. The use of a sterically unhindered pyridine base
Zn(II)-Catalyzed One-Pot Synthesis of Coumarins from Ynamides and Salicylaldehydes
作者:Huen Ji Yoo、So Won Youn
DOI:10.1021/acs.orglett.9b01181
日期:2019.5.3
A highly efficient and straightforward synthesis of diversely substituted coumarins from ynamides and salicylaldehydes in the presence of Zn(II) catalyst has been developed. The sulfonamide moiety of ynamides was successfully recycled in this process, serving as an effective traceless directing group for high regioselectivity in the bond-forming event. The advantages of this protocol are good functional
Rhodium-catalyzed Direct Coupling of Benzothioamides with Alkenes and Alkynes through Directed C–H Bond Cleavage
作者:Yuki Yokoyama、Yuto Unoh、Rebekka Anna Bohmann、Tetsuya Satoh、Koji Hirano、Carsten Bolm、Masahiro Miura
DOI:10.1246/cl.150444
日期:2015.8.5
Rhodium-catalyzed direct coupling of benzothioamides with alkenes proceeds smoothly involving ortho-C–H bond cleavage. The thioamides also couple with alkynes under similar conditions accompanied b...