791074-34-5Relevant academic research and scientific papers
An improved class of phosphite-oxazoline ligands for Pd-catalyzed allylic substitution reactions
Biosca, Maria,Salto, Joan,Magre, Marc,Norrby, Per-Ola,Pamies, Oscar,Dieguez, Montserrat
, p. 6033 - 6048 (2019/07/19)
A method for generation of Pd/phosphite-oxazoline catalysts containing an alkyl backbone chain has been successfully applied to Pd-catalyzed allylic substitution reactions. By carefully selecting the substituents at both the alkyl backbone chain and the oxazoline of the ligand, as well as the configuration of the biaryl phosphite group, high activities (TOF > 8000 mol substrate × (mol Pd × h)?1) and excellent enantioselectivities (ee's up to 99%) have been achieved for many hindered and unhindered substrates with a wide range of C-, O-, and N-nucleophiles (73 substitution products in total). Moreover, DFT and NMR studies of the key Pd-allyl complexes allowed us to better understand the origin of the excellent enantioselectivities observed experimentally. The useful application of the Pd/phosphite-oxazoline catalysts was demonstrated by the syntheses of many chiral carbobicycles, with multiples stereocenters, by simple sequential reactions involving Pd-allylic substitution and either 1,6-enyne cyclization or Pauson?Khand enyne cyclization.
Asymmetric Hydrogenation of Disubstituted, Trisubstituted, and Tetrasubstituted Minimally Functionalized Olefins and Cyclic β-Enamides with Easily Accessible Ir-P,Oxazoline Catalysts
Biosca, Maria,Magre, Marc,Pàmies, Oscar,Diéguez, Montserrat
, p. 10316 - 10320 (2018/10/20)
We have developed a family of Ir-P,oxazoline catalysts for asymmetric hydrogenation. These catalysts, with a simple modular architecture, have shown a high tolerance to the olefin geometry and substitution pattern, and to the presence of several neighboring polar groups. Thus, they were able to successfully hydrogenate disubstituted, trisubstituted, and tetrasubstituted minimally functionalized olefins (with enantiomeric excess values up to 99%). The excellent catalytic performance was also extended to the hydrogenation of cyclic β-enamides.
Convenient synthesis of a new class of chiral hydroxymethyl-dihydrooxazole ligands and their application in asymmetric addition of diethylzinc to aromatic aldehydes
Li, Zhi-Ting,Li, Xin-Sheng,Li, Liang-Chao,Xu, Dong-Cheng
, p. 545 - 549 (2007/10/03)
A number of chiral hydroxymethyl-substituted dihydrooxazoles were synthesized from D- or L-mandelic acid and amino alcohols. The chiral ligands thus obtained were tested as catalyst in the asymmetric addition of diethylzinc to aromatic aldehydes, and the
New chiral ligands derived from mandelic acid: Synthesis and application in the asymmetric phenyl transfer reaction to an aromatic aldehyde
Bolm, Carsten,Zani, Lorenzo,Rudolph, Jens,Schiffers, Ingo
, p. 2173 - 2180 (2007/10/03)
Starting from inexpensive enantiopure (R)- and (S)-mandelic acid, a range of α-hydroxy-2-oxazolines has been prepared. The synthesis involves the condensation of the acid chloride with a vicinal amino alcohol, followed by intramolecular cyclization to form the oxazoline ring. The resulting compounds have been used as ligands in the asymmetric phenyl transfer reaction to 4-chlorobenzaldehyde, employing a mixture of triphenylborane and diethylzinc as the phenyl source. Good yields (up to 76%) and moderate enantioselectivities (up to 35%) have been achieved.
