Rhodium and iridium complexes of Schiff's bases derived from (1 R,2R)- and (1S,2S).-di-aminocyclohexane catalyze asymmetric transfer hydrogenation of alkyl aryl ketones in (PrOH)-O-i at room temperature to give chiral secondary alcohols (up to 65% ee).
Zinc acetate complexes with a chiral diphenylethylenediamine (DPEDA)-derived ligand have been proved to be efficient catalysts for the enantioselectivehydrosilylation of aryl ketones. Replacing pyrophoric dialkylzinc with the readily available zinc salt simplifies the procedures and provides excellent conversions (up to >99%) and enantioselectivities (ees up to 97%).
The asymmetric synthesis of α-substituted α-methyl and α-phenyl phosphonic acids: Design, carbanion geometry, reactivity and preparative aspects of chiral alkyl bicyclic phosphonamides
作者:Youssef L. Bennani、Stephen Hanessian
DOI:10.1016/0040-4020(96)00829-0
日期:1996.10
The design, preparation, structural and spectroscopic analyses of topologically unique and enantiomerically pure alkylphosphonamides are described. In the case of α-ethyl and α-benzyl phosphonamides, the geometry of both the secondary and tertiary carbanions was determined to be planar through deprotonation/deuteration/alkylation experiments. Stereoselective alkylations of such systems proceeded in
and their reduced diamine counterparts 3b,3d–3g and 3i form complexes 4a–4i, 5b,5d–5g, and 5i with PdCl2 in DMF or methanol. Using 1 mol-% of the isolated complexes 4e and 5f many polychlorinated biphenyls (PCBs) can be prepared in moderate to excellent yields according to the Suzuki crosscoupling protocol with contact to air. Several 4-acetylbiphen
Asymmetric allylation reactions of aromatic aldehydes with allyltrichlorosilane catalyzed by chiral bisformamide-type organocatalysts
作者:Yuya Tanimura、Kaori Ishimaru
DOI:10.1016/j.tetasy.2012.02.015
日期:2012.3
Asymmetricallylation reactions of aromatic aldehydes with allyltrichlorosilane were catalyzed by C2-symmetrical chiral bisformamides in the presence of potassium carbonate and potassium phosphate, to afford the corresponding homoallylic alcohols in excellent yields with up to 83% ee.
A series of N,N′-dialkylated derivatives of (1R,2R)-cyclohexane-1,2-diamine were synthesized, and a new approach to the one-pot preparation of this type of amine was demonstrated. The prepared diamines were used as organocatalysts for the two-stepsynthesis of α-hydroxy γ-keto esters from arenes, chlorooxoacetates, and ketones; they were also used as chiral ligands for Meervein–Ponndorf–Verley reductions