504-61-0Relevant articles and documents
Crotonaldehyde hydrogenation by gold supported on TiO2: Structure sensitivity and mechanism
Zanella, Rodolfo,Louis, Catherine,Giorgio, Suzanne,Touroude, Raymonde
, p. 328 - 339 (2004)
The catalytic properties of two series of Au/TiO2 catalysts prepared by deposition-precipitation with NaOH (DP NaOH) (～3 wt%) and by deposition-precipitation with urea (DP Urea) (～8 wt%) were evaluated for the reaction of crotonaldehyde hydrogenation at atmospheric pressure. There is no difference in activity (molgAu-1s-1) and selectivity between the DP Urea and DP NaOH samples for a given activation treatment. This is due to the fact that the DP Urea and DP NaOH samples exhibit a similar gold particle size distribution, although the gold loading in DP Urea catalysts is much higher than in DP NaOH. The DP Urea samples were reduced under H2 at different temperatures (120-500°C) or treated in air at 300°C with various flow rates, to vary the average particle size within a large range, 1.7 to 8.7 nm. The selectivity to crotyl alcohol (selective hydrogenation of the carbonyl bond), in the 5-50% conversion range, is high, 60-70 %, and is independent of the reduction temperature, and almost constant as a function of the particle size. In contrast, the TOF depends on the gold particle size, drastically increasing when the gold particle size is ～2 nm. These characteristic features of Au/TiO2 catalysts in this reaction are compared with those of Pt/TiO2. The possible adsorption modes of crotonaldehyde are discussed. Hydrogen dissociation is proposed to be the rate-determining step, and to take place on the low-coordinated atoms of the gold particles.
Alkyne Aminopalladation/Heck and Suzuki Cascades: An Approach to Tetrasubstituted Enamines
Geffers, Finn J.,Jones, Peter G.,Kurth, Florens R.,Werz, Daniel B.
supporting information, p. 14846 - 14850 (2021/10/19)
Alkyne aminopalladation reactions starting from tosylamides are reported. The emerging vinylic Pd species are converted either in an intramolecular Heck reaction with olefinic units or in an intermolecular Suzuki reaction by using boronic acids exhibiting broad functional group tolerance. Tetra(hetero)substituted tosylated enamines are obtained in a simple one-pot process.
Molecular Recognition and Cocrystallization of Methylated and Halogenated Fragments of Danicalipin A by Enantiopure Alleno-Acetylenic Cage Receptors
Carreira, Erick M.,Diederich, Fran?ois,Fischer, Stefan,Gropp, Cornelius,Husch, Tamara,Trapp, Nils
supporting information, (2020/03/13)
Enantiopure (P)4- and (M)4-configured alleno-acetylenic cage (AAC) receptors offer a highly defined interior for the complexation and structure elucidation of small molecule fragments of the stereochemically complex chlorosulfolipid danicalipin A. Solution (NMR), solid state (X-ray), and theoretical investigations of the formed host-guest complexes provide insight into the conformational preferences of 14 achiral and chiral derivatives of the danicalipin A chlorohydrin core in a confined, mostly hydrophobic environment, extending previously reported studies in polar solvents. The conserved binding mode of the guests permits deciphering the effect of functional group replacements on Gibbs binding energies ΔG. A strong contribution of conformational energies toward the binding affinities is revealed, which explains why the denser packing of larger apolar domains of the guests does not necessarily lead to higher association. Enantioselective binding of chiral guests, with energetic differences ΔΔG293 K up to 0.7 kcal mol-1 between diastereoisomeric complexes, is explained by hydrogen- and halogen-bonding, as well as dispersion interactions. Calorimetric studies (ITC) show that the stronger binding of one enantiomer is accompanied by an increased gain in enthalpy ΔH but at the cost of a larger entropic penalty TΔS stemming from tighter binding.
Formal synthesis of borrelidin: A highly enantio- and diastereoselective access to the Morken's C2-C12 intermediate
Gembus, Vincent,Karmazin, Lydia,Uguen, Daniel,Zoller, Thomas
supporting information, p. 359 - 380 (2019/02/25)
In contrast to methyl and isobutyl phenyl sulfone, condensing under basic conditions higher alkyl sulfones and trans-2,3-epoxy-butanol 13c (or its O-benzyl and O-silyl derivatives) proved unfeasible, a difficulty that was overcome by using mono ethers of trans-2,3-epoxy-butane-1,4-diol 35c as the electrophilic reagents. Thus, adding excess BuLi to a mixture of the benzyl ether 35b and sulfone ent-12a, a stereodiad sulfone prepared in pure state from the R-Roche ester, via the O-trityloxy-sulfone ent-12c (X-ray), gave, after elimination by column chromatography of the side-formed regioisomer, a diolsulfone that was next converted to sulfone 20 by means of conventional functional-group modifications. Reacting like-wise this sulfone with the parent O-PMB derivative 35a, and then proceeding to the same purification process and function adjustment, delivered the title fragment in virtually pure state.
