23719-81-5Relevant academic research and scientific papers
Carbon-13 nuclear magnetic resonance studies of tricyclopropylaluminum, -gallium, and -indium
Thomas, Ruthanne D.,Oliver, John P.
, p. 571 - 579 (1982)
13C NMR studies have been carried out on tricyclopropylaluminium, -gallium, and -indium. The concentration and temperature dependence of the NMR spectra of the aluminum derivative have been interpreted in terms of a singlely bridged intramolecular bridge-terminal exchange process with activation parameters of Ea? + 12,4 (2)kcal/mol, ΔH? + 11,7 (2)kcal/mol, and ΔS? -13,1 (1.2) eu. Investigation of the 13C spin-lattice relxation times at low temperature and calculation of the relative spinning rates, ρ, of the cyclopropyl groups shows that the bridging cyclopropyl groups and the terminal cyclopropyl groups lying on the same side of the A1-C-A1-C rings rotate at the same rats, while the terminal groups on the opposite side rotate at 5-8 times this rate. This confirms the proposal that the low-temperature averaging process observed is a result of the variations in the rotation rate of the bridging cyclopropyl group and not from freezing the terminal cyclopropyl groups in different configurations. The study of the gallium and indium derivatives shows that their 13C chemical shifts are highly dapendent on temperature, concentration, and solvent. The measurement of the temperature and concentration dependence of these chemical shifts leads to the conclusion that these species are involved in an equilibrium between monomer and dimer and that the shift in the relative concentration of these two species leads to the observed changes in chemical shift. On this basis, equilibrium constants and enthalpies of dissociation have been calculated. The enthalpies of dissociation obtained for toluene solutions are 5.6 and 4.0 kcal/mol for the gallium and indium compounds, respectively.
Transition-Metal-Free Cross-Coupling of Indium Organometallics with Chromene and Isochroman Acetals Mediated by BF3·OEt2
Gil-Negrete, José M.,Sestelo, José Pérez,Sarandeses, Luis A.
, p. 4316 - 4319 (2016/10/12)
A transition-metal-free coupling of triorganoindium reagents with benzopyranyl acetals mediated by a Lewis acid has been developed. The reaction of R3In with chromene and isochroman acetals in the presence of BF3·OEt2 afforded 2-substituted chromenes and 1-substituted isochromans, respectively, in good yields. The reactions proceed with a variety of triorganoindium reagents (aryl, heteroaryl, alkynyl, alkenyl, alkyl) using only 50 mol % of the organometallic, thus demonstrating the efficiency of these species. Preliminary mechanistic studies indicate the formation of an oxocarbenium ion intermediate in the presence of the Lewis acid.
Atom-efficient metal-catalyzed cross-coupling reaction of indium organometallics with organic electrophiles
Perez,Sestelo,Sarandeses
, p. 4155 - 4160 (2007/10/03)
The novel metal-catalyzed cross-coupling reaction of indium organometallics with organic electrophiles is described. Triorganoindium compounds (R3In) containing alkyl, vinyl, aryl, and alkynyl groups are efficiently prepared from the correspond
