Efficient Access to Chiral Benzhydrols via Asymmetric Transfer Hydrogenation of Unsymmetrical Benzophenones with Bifunctional Oxo-Tethered Ruthenium Catalysts
A concise asymmetric transfer hydrogenation of diaryl ketones, promoted by bifunctional Ru complexes with an etherial linkage between 1,2-diphenylethylenediamine (DPEN) and η(6)-arene ligands, was successfully developed. Because of the effective discrimination of substituents at the ortho position on the aryl group, unsymmetrical benzophenones were smoothly reduced in a 5:2 mixture of formic acid and
Evaluation of Enantiopure <i>N</i>-(Ferrocenylmethyl)azetidin-2-yl(diphenyl)methanol for Catalytic Asymmetric Addition of Organozinc Reagents to Aldehydes
作者:Min-Can Wang、Qing-Jian Zhang、Wen-Xian Zhao、Xiao-Dan Wang、Xue Ding、Tao-Tao Jing、Mao-Ping Song
DOI:10.1021/jo701943x
日期:2008.1.1
catalytic asymmetric addition of organozinc reagents to aldehydes. The asymmetric ethylation, methylation, arylation, and alkynylation of aldehydes achieved enantioselectivity of up to 98.4%, 94.1%, 99.0%, and 84.6% ee, respectively, in the presence of a catalytic amount of chiral N-(ferrocenylmethyl)azetidin-2-yl(diphenyl)methanol. Our results demonstrated further that the four-membered heterocycle-based
Ligand design by‐pam: A ruthenium‐catalyzed asymmetric arylation of aldehydes with arylboronicacids has been developed, giving chiral diarylmethanols in good yields. The use of a chiral bidentate phosphoramidite ligand ((R,R)‐Me‐bipam) led to excellent enantioselectivities.
Addition of AlMe3 to commercial THF solutions of RZnX (R = aryl, functionalised aryl, vinyl; X = Br, I) simultaneously promotes Schlenk equilibria (leading to competent nucleophiles) and the formation of an Al–Zn-ligand catalyst delivering 80–90% ee for Ar1CH(OH)Ar2 formation from aldehydes.
On the Scope of Trimethylaluminium-Promoted 1,2-Additions of ArZnX Reagents to Aldehydes
作者:Daniel Glynn、Jonathan Shannon、Simon Woodward
DOI:10.1002/chem.200901803
日期:2010.1.18
functionalised arylzinc halides to aromatic and aliphatic aldehydes is described by the use of aminoalcohol 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 ArZnXreagents or those prepared in situ from low cost aryl bromides