290332-34-2Relevant academic research and scientific papers
An outstanding palladium system containing a C2-symmetrical phosphite ligand for enantioselective allylic substitution processes
Balanta Castillo, Angelica,Favier, Isabelle,Teuma, Emmanuelle,Castillon, Sergio,Godard, Cyril,Aghmiz, Ali,Claver, Carmen,Gomez, Montserrat
, p. 6197 - 6199 (2008)
The use of efficient Pd systems bearing C2-symmetric chiral diphosphite ligands derived from carbohydrates in asymmetric allylic substitution reactions is described here, reaching TOFs > 22 000 h -1 in allylic alkylation and ca. 400 h-1 in allylic amination, giving excellent enantioselectivities (ee > 99%) and kinetic resolution of the racemic substrate. The Royal Society of Chemistry.
C1-Symmetric carbohydrate diphosphite ligands for asymmetric Pd-allylic alkylation reactions. Study of the key Pd-allyl intermediates
Gual, Aitor,Castillon, Sergio,Pamies, Oscar,Dieguez, Montserrat,Claver, Carmen
experimental part, p. 2852 - 2860 (2011/05/14)
A series of C1-symmetrical 1,3-diphosphite ligands with a furanoside backbone have been applied in the Pd-catalysed asymmetric allylic alkylation of mono- and disubstituted linear substrates. These diphosphite ligands were designed by selective
Modular chiral diphosphite derived from l-tartaric acid. Applications in metal-catalyzed asymmetric reactions
Rosas-Hernández, Alonso,Vargas-Malvaez, Edgar,Martin, Erika,Crespi, Laura,Bayón, J. Carles
experimental part, p. 68 - 75 (2010/11/05)
A new family of C2-symmetric chiral diphosphites was synthesized using two different chiral backbones derived from tartaric acid, combined with chiral binaphthyls or non-chiral substituted biphenyl moieties. Diphosphites were applied to Rh-catalyzed hydroformylation of styrene producing good conversions in mild conditions, fair regioselectivities but low enantioselectivities in all cases. Ligands were also essayed in Pd-catalyzed allylic substitution reactions of linear and cyclic substrates using dimethyl malonate as nucleophile. Conversion rates up to 7200 h-1 were reached, while moderated ee's were attained. In this reaction, a kinetic resolution of rac-1,3-diphenyl-3-acetoxyprop-1-ene was observed, leading to 99% ee of for the unreacted S-substrate and 60% ee of S-alkylated product. Coordination properties of diphosphites in rhodium and palladium complexes related to catalytic species involved in the two previous reactions were investigated. Some ligands form equatorial-equatorial chelates in pentacoordinated complexes [RhH(CO)(PPh3)(diphosphite)], while other act as bridge between two metal atoms. In the catalytic active species [Pd(η3-PhCHCHCHPh)(diphosphite)]PF6 one or two diastereoisomers are formed, depending on the diphosphite structure.
