RESUMEN
A reaction of intramolecularly disposed phosphonium and phenoxide (or thiophenoxide) fragments with difluorocarbene affording all-carbon λ5-phosphoranes is described. The presence of electron-withdrawing CHF2-groups at the phosphonium center is important for the phosphorane formation. In a phosphorane, both phenyl groups located in the equatorial positions undergo 1,2-P,C migration under thermal conditions.
RESUMEN
Compounds bearing ortho-oriented dialkylamino and boryl groups can serve as efficient reagents to trap difluorocarbene leading to zwitterionic ammonium borates featuring N-CF2-B fragments. The reagents are shelf-stable and can be used as mechanistic probes for reactions proceeding via difluorocarbene.
RESUMEN
Frustrated Lewis pairs consisting of diphenylphosphino and boryl groups located at the ortho-position can trap difluorocarbene affording stable zwitterionic adducts. The reaction can be reversed to release difluorocarbene at elevated temperatures.
RESUMEN
A method for the generation of the CF3 radical from CF3-substituted borate complexes bearing a pyridine-N-oxide ligand is described. Cleavage of the C-B bond occurs via single electron reduction by a Cu(i) photocatalyst activated by visible light.
RESUMEN
A method for the synthesis of 3-fluoroindoles from N-arylamines substituted with the CF2I group is described. The reaction is mediated by a ruthenium photocatalyst in the presence of a substoichiometric amount of triphenylphosphine upon irradiation with blue light. The starting N-arylamines are readily obtained by nucleophilic iododifluoromethylation of iminium ions.
RESUMEN
A method for the iododifluoromethylation of aromatic aldehydes using (bromodifluoromethyl)trimethylsilane (Me3SiCF2Br) is described. The selective formation of the CF2I group is based on using sodium iodide, with the sodium serving as a scavenger of bromide and iodide serving as a nucleophile with respect to difluorocarbene. The primary CF2I-addition products can undergo HI-elimination or iodine/zinc exchange followed by allylation in a one-pot manner.
RESUMEN
A method for the synthesis of gem-difluorinated nitroso compounds is described. The reaction involves interaction of organozinc reagents with (bromodifluoromethyl)trimethylsilane followed by nitrosation of difluorinated organozinc species with an n-butyl nitrite/chlorotrimethylsilane system.
Asunto(s)
Hidrocarburos Fluorados/química , Indicadores y Reactivos/química , Nitritos/química , Compuestos Nitrosos/síntesis química , Compuestos de Trimetilsililo/química , Concentración de Iones de Hidrógeno , Estructura Molecular , Nitrosación , Compuestos Nitrosos/químicaRESUMEN
Silylation of various nitronates with trialkylsilyl triflates was investigated by applying NMR techniques. In several cases, a flexible nitronate-bis(oxy)iminium ion (as an ion pair with triflate as counterion) equlibrium was found, and its thermodynamic parameters were determined. Elevation of temperature or dilution shifts this equilibrium toward the reactants. Activation parameters for the C,C-coupling reaction of silylated bis(oxy)iminium ions with a series of reference nucleophiles were determined. Estimated electrophilicity of bis(oxy)iminium ions allows one to count on C,C-coupling when partner nucleophilicity is N > 4.
RESUMEN
Cyclic six-membered nitronates 1 are involved in diastereoselective C-C coupling reactions with various nucleophiles in the presence of either catalytic or stoichiometric amounts of TBDMSOTf to give the previously unknown N-siloxytetrahydrooxazines. The intermediacy of N,N-bis(oxy)iminium cations was proven by NMR data.