Synthesis of Isochromanes and Isothiochromanes Bearing Fluorinated One-Carbon Units via Intramolecular Cyclizations of ortho-Substituted α-(Trifluoromethyl)styrenes
摘要:
alpha-(Trifluoromethyl)styrenes bearing a nucleophilic oxygen or sulfur atom tethered by a methylene or methyne unit at the ortho carbon were prepared by the coupling reaction of 2-bromo-3,3,3-trifluoropropene with aryl iodides via (3,3,3-trifluoroprop-1-en-2-yl) boronic acid. The styrenes thus obtained readily undergo an intramolecular nucleophilic addition or substitution (S(N)2'-type) of the oxygen and sulfur under basic conditions, leading to 4-trifluoromethyl- or 4-difluoromethylene-substituted isochromanes and isothiochromanes, respectively.
Synthesis of 2-Fluorobenzofuran by Photocatalytic Defluorinative Coupling and 5<i>-endo-trig</i> Cyclization
作者:Xiaoli He、Jiahao Ling、Zhixing Fang、Lei Zhou
DOI:10.1021/acs.joc.3c00559
日期:2023.6.2
An alkyl radical-triggered dual C–F bondcleavage of α-CF3-ortho-hydroxystyrenes for the synthesis of 2-fluorobenzofurans was developed. The visible-light-induced defluorinative cross-coupling reactions of α-CF3-ortho-hydroxystyrenes with a variety of carboxylic acids produced gem-difluoroalkenes, which underwent SNV-type 5-endo-trig cyclization to give 2-fluorobenzofurans. Mechanistic studies indicated