Treatment of various fluorinated internal alkynes with 10 mol% of RhCl3·H2O and 30 mol% of i-Pr2NEt in toluene at the reflux temperature for 18 h gave the corresponding trimerization products as an isomeric mixture in high yields. Cycloaddition using 1.0 equiv. of fluorinated alkynes and 2.0 equiv. of non-fluorinated alkynes under the same reaction conditions as in the trimerization led to mono- and
It found that the Ru3(CO)12 coordinated with 2-(diphenylphosphino)benzonitrile (2-DPPBN) to effectively catalyze the [2 + 2 + 2] cyclotrimerization of the trifluoromethyl group substituted internal alkynes in high yields with up to >98% regioselectivity. Isolation of a ruthenacyclopentadiene was successful and confirmed that the complex is a reaction intermediate.
First practical synthesis of 2- or 3-fluoroalkylated indenols via cobalt-catalyzed [2 + 3] carbocyclization of fluorine-containing alkynes and 2-iodoaryl ketones
[2 + 3] Cycloaddition reaction of fluorine-containing alkynes with various 2-iodoaryl ketones in the presence of CoCl2(dppf) catalyst proceeded very smoothly to give the corresponding 2- or 3-fluoroalkylated indenols in 57–98% yields. These regioisomers could be successfully separated and obtained in a pure form. From X-ray crystallographic and NOESY analyses, major or minor regioisomers were determined
Highly regioselective cobalt-catalyzed [2+2+2] cycloaddition of fluorine-containing internal alkynes to construct various fluoroalkylated benzene derivatives
cobalt-catalyzed [2+2+2] cycloaddition using fluorine-containing alkynes was described. Cyclotrimerization of fluorinated alkynes under the influence of CoCl2(dppb) in acetonitrile at 80 °C for 3 h took place smoothly, affording the corresponding benzene derivatives in excellent yields with high regioselectivity. Additionally, intermolecular cycloaddition of fluorinated alkynes with non-fluorinated diynes