Fluoroform (CF(3)H), a large-volume by-product of the manufacture of Teflon, refrigerants, polyvinylidene fluoride (PVDF), fire-extinguishing agents, and foams, is a potent and stable greenhouse gas that has found little practical use despite the growing importance of trifluoromethyl (CF3) functionality in more structurally elaborate pharmaceuticals, agrochemicals, and materials. Direct nucleophilic trifluoromethylation using CF(3)H has been a challenge. Here, we report on a direct trifluoromethylation protocol using close to stoichiometric amounts of CF(3)H in common organic solvents such as tetrahydrofuran (THF), diethyl ether, and toluene. The methodology is widely applicable to a variety of silicon, boron, and sulfur-based electrophiles, as well as carbon-based electrophiles.
Highly versatile: The Ruppert–Prakash reagent (Me3SiCF3) can be an efficient source of difluorocarbene. By varying the nonmetallic initiator that is used (F− at lower temperatures and I− at higher temperatures), a range of structurally diverse alkenes and alkynes can be converted into the corresponding gem‐difluorinated cyclopropanes and cyclopropenes in good yields (see scheme).
A gated synthetic ion channel with beta-cyclodextrin as the pore and azobenzene as the gate is reported. Irradiation converts a tethered trans-azobenzene to cis-azobenzene which likely transforms the channel from a self-inclusion complex to a dissociated structure. This transformation results in an increase in anion transport and a decrease in cation transport across a phospholipid vesicle membrane.
Sehr vielseitig: Das Ruppert‐Prakash‐Reagens (Me3SiCF3) kann eine effiziente Quelle für Difluorcarben sein. Durch Variation des verwendeten, nichtmetallischen Initiators (F− bei tiefen Temperaturen und I− bei hohen Temperaturen) wurden verschiedene Alkene und Alkine mit guter Ausbeute in ihre entsprechenden gem‐difluorierten Cyclopropane bzw. Cyclopropene umgesetzt (siehe Schema).
A domino approach of Heck coupling was used to synthesize β-trifluoromethylstyrene derivatives from iodoarenes and 1-iodo-3,3,3-trifluoropropane in moderate to good yields. This method avoids the use of low-boiling, gaseous reagents such as 3,3,3-trifluoropropene, and additives and phosphines in the catalytic system.
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