61986-69-4Relevant academic research and scientific papers
On the scope of trimethylaluminium-promoted 1,2-additions of ArZnX reagents to aldehydes
Glynn, Daniel,Shannon, Jonathan,Woodward, Simon
supporting information; experimental part, p. 1053 - 1060 (2010/05/19)
A practical asymmetric 1, 2 addition of functionalised arylzinc hal ides to aromatic and aliphatic aldehydes is described by the use of amino alcohol catalysis in the presence of AlMe3. The process is simple to carry out, uses only commercially available reagents/ligands and provides moderate to good (80-96% ee) enantioselectivities for a wide range of substrates. Either commercial ArZnX reagents or those prepared in situ from low cost aryl bromides can be used. In the latter case electrophilic functional groups are tolerated (CO2Et, CN). The reaction relies on rapid exchange between ArZnX and AlMe3 to generate mixed organometallic species that lead to the formation of a key intermediate that is distinctly different from the classic "anti" transition states of Noyori. NMR monitoring and related experments have been used to probe the validity of the proposed selective transition state.
Enantioselective hydrogenation and transfer hydrogenation of bulky ketones catalysed by a ruthenium complex of a chiral tridentate ligand
Diaz-Valenzuela, M. Belen,Phillips, Scott D.,France, Marcia B.,Gunn, Mary E.,Clarke, Matthew L.
experimental part, p. 1227 - 1232 (2009/08/10)
A study on the enantioselective hydrogenation of tertiary alkyl ketones catalysed by a novel class of tridentate-Ru complex is reported. In contrast to the extensively studied [RuCl2(diphos)(di-primary amine)] complexes, this new class of hydro
A highly enantioselective phosphabicyclooctane catalyst for the kinetic resolution of benzylic alcohols
Vedejs, Edwin,Daugulis, Olafs
, p. 4166 - 4173 (2007/10/03)
A new class of chiral phosphines belonging to the P-aryl-2-phosphabicyclo[3.3.0]octane family (PBO) has been prepared by enantioselective synthesis starting from lactate esters and 2,2-dimethylcy-clopentanone enolate 5. A selective enolate alkylation method has been developed for preparation of 9 and 10 using a chelating ester substituent in the triflate alkylating agent 11. Subsequent conversion to the PBO catalysts 2 and 39 relies on a diastereoselective cyclization from the cyclic sulfate 17 and LiPHAr to afford the more hindered endo-aryl phosphines. These phosphines function as efficient catalysts for the kinetic resolutions of aryl alkyl carbinols by benzoylation (16, 21, 22) or iso-butyroylation in the case of the less hindered aryl alkyl carbinol substrates. With o-substituted aryl alkyl carbinols, the enantioselectivities exceed 100, and s = 380 ± 10 has been demonstrated in the case of methyl mesityl carbinol. The PBO- catalyzed acylations probably involve a P-acylphosphonium carboxylate intermediate and a tightly ion paired transition state.
