Iron-Catalyzed Preparation of Trifluoromethyl Substituted Vinyl- and Alkynylcyclopropanes
摘要:
A convenient iron-catalyzed procedure to prepare trifluoromethylated vinyl- and alkynylcyclopropanes in a chemo- and diastereoselective manner Is presented. The active diazo compound (trifluoromethyl diazomethane) is generated in situ and used in the concomitant cyclopropanation reaction.
Iron-Catalyzed Preparation of Trifluoromethyl Substituted Vinyl- and Alkynylcyclopropanes
摘要:
A convenient iron-catalyzed procedure to prepare trifluoromethylated vinyl- and alkynylcyclopropanes in a chemo- and diastereoselective manner Is presented. The active diazo compound (trifluoromethyl diazomethane) is generated in situ and used in the concomitant cyclopropanation reaction.
Synthesis of Ring-Fluorinated Thiophene Derivatives Based on Single C–F Bond Activation of CF<sub>3</sub>-Cyclopropanes: Sulfanylation and 5-<i>endo</i>-<i>trig</i> Cyclization
作者:Kohei Fuchibe、Tatsuki Fushihara、Junji Ichikawa
DOI:10.1021/acs.orglett.0c00385
日期:2020.3.20
The treatment of CF3-bearing cyclopropanes with Et2AlCl generated stabilized difluorocarbocations, which underwent a nucleophilic addition of thiocarboxylic acids or thiols. The sulfur functionality was introduced at the position δ to the fluorine substituents in a regioselective manner (single activation of CF3-cyclopropanes). The formed 1,1-difluoro-1-alkenes underwent successive deesterification/5-endo-trig
The trifluoromethylcarbene (:CHCF3) was found to be conveniently generated from (2,2,2-trifluoroethyl)diphenyl-sulfonium triflate (Ph2S+CH2CF3–OTf), which was successfully applied in Fe-catalyzed cyclopropanation of olefins, giving the corresponding trifluoromethylated cyclopropanes in high yields.
vinyl amines, vinyl carbamates and dienes, was achieved by using Ru(II)–Pheox catalysts. This catalytic system can function at a low catalyst loading (3 mol%) compared with those reported previously, and the desired cyclopropane products are obtained in high yields with excellent diastereoselectivity (up to >99 : 1) and enantioselectivity (up to 97% ee).