Computed Properties of C25H26NOPIn 2002, Fairlamb, Ian J. S.;Lloyd-Jones, Guy C.;Vyskocil, Stepan;Kocovsky, Pavel published 《Analysis of stereochemical convergence in asymmetric Pd-catalysed allylic alkylation reactions complicated by halide and memory effects》. 《Chemistry – A European Journal》published the findings. The article contains the following contents:
A quant. two-term description of memory effects arising in Pd-catalyzed allylic alkylation reactions formally proceeding through ‘meso’-type π-allylpalladium intermediates is presented. The utility of this description (stereochem. convergence (s.c.) and global enantiomeric excess (eeg)) is demonstrated by application to a series of Pd-catalyzed allylic alkylation reactions involving racemic cyclopentenyl esters. Anal. of such reactions, by employing a range of enantiomerically pure monophosphine ligands, reinforces the conclusion that selectivities (enantiomeric excess (ee) values) obtained under standard ‘benchmark’ type conditions may be very misleading when powerful memory effects are operative. By comparison of s.c. and ee for a given ligand/solvent combination under a range of related conditions, however, one may predict the limiting (‘latent’) selectivity that will be obtained when the memory effect is negated. This technique is exemplified with one particular ligand [I; wherein Z = NMe2] for which a number of strategies were employed to find conditions that negate the memory effect and reveal the limiting selectivity of the ligand. These conditions give a higher limiting global selectivity than that obtainable by using standard diastereoisomer equilibration methods such as added halide. Thus, the anal. of s.c. vs. eeg also allows subtle changes in selectivity to be discerned. The difference in limiting selectivity (chloride vs. non-chloride conditions) is proposed to arise through the nucleophilic attack of neutral monodentate vs. cationic bidentate complexes I (wherein Z = NMe2, OMe). The experimental procedure involved many compounds, such as (S)-2-(2-(Diphenylphosphanyl)phenyl)-4-isobutyl-4,5-dihydrooxazole (cas: 167693-62-1) .
(S)-2-(2-(Diphenylphosphanyl)phenyl)-4-isobutyl-4,5-dihydrooxazole(cas: 167693-62-1) is a compound of chiral-phosphine-ligands. At present, the synthesis of new chiral phosphines designed specifically for nucleophilic organocatalysis remains a significant challenge.Computed Properties of C25H26NOP
Reference:
Phosphine ligand,
Chiral phosphines in nucleophilic organocatalysis