The reaction of acetophenones with iodine(III) tris(trifluoroacetate) yields 3′- and/or 2-iodo derivatives, depending upon the substituent on the aromatic ring and the reaction conditions. The reaction was examined by changing the molar ratio of acetophenone versus the reagent, reaction temperature, and solvent. In similar reactions flavanones and coumarins gave iodo derivatives in which iodine is incorporated
Reaction of 4-hydroxycoumarin or its<i>O</i>-substituted derivatives with diatomic interhalogens: ICl and IBr
作者:Marcel Mirel Popa、Constantin Draghici、Loredana Barbu、Denisa E. Dumitrescu、Florea Dumitrascu
DOI:10.1080/00397911.2016.1264603
日期:2017.2.16
ABSTRACT Herein, we present some aspects regarding the iodination/bromination of 4-hydroxycoumarin or its O-methyl or O-acetyl derivatives with iodine monochloride or iodine monobromide as halogenation reagents. Also, the investigation of photochemical transformation of the three 3-iodocoumarins was investigated for the first time. GRAPHICAL ABSTRACT
The Pd-catalyzed cyclofunctionalization of 3-alkynyl-4-methoxycoumarins with aryl halides resulted In the selective formation of 3-arylfuro[3,2-c]coumarins in lieu of the expected regioisomeric 3-arylfuro[2,3-b]chromones. A mechanism involving the linear to angular rearrangement of a Pd-containing furan intermediate was proposed.
Et<sub>3</sub>N-Induced Demethylation−Annulation of 3-Alkynyl-4-methoxy-2-pyridones and Structurally Related Compounds in the Synthesis of Furan-Fused Heterocycles
Various 3-iodo-4-methoxypyridin-2-ones and related pyrone and coumarin derivatives have been demonstrated as readily available precursors of 2-substituted furan-fused heterocycles by means of in situ sequential Sonogashira-acetylide coupling. dealkylation, and regioselective furan annulation reactions. A Et3N-induced S(N)2 process has been established that accounts for the dealkylation process.