New chiral ammonium salt hosts derived from amino acids: very efficient optical resolution of 2,2′-dihydroxy-1,1′-binaphthyl by complexation with these host compounds
Asymmetric Sulfinylations of<i>N</i>-Methylephedrine-Modified Tri- or Tetraalkyl Zincates by Symmetric Diaryl Sulfoxides
作者:Simon Ruppenthal、Reinhard Brückner
DOI:10.1002/ejoc.201701603
日期:2018.6.7
Diethylzinc was treated with 1 or 2 equiv. of AlkMgCl or PhMgBr (preferably) or with 1 equiv. of nBuLi (less efficiently) for forming species – plausibly zincates – which were sulfinylated by diaryl sulfoxides to give racemic alkyl aryl sulfoxides in yields reaching 100 %. Dialkylzinc reagents were also activated by treatments with 1 or 2 equiv. of an enantiomericallypure alkylmagnesium β‐aminoalkoxide
Axially chiral trifluoromethylbenzimidazolylbenzoic acid (TBBA) was used as a chiral derivatization agent for the assignment of the absoluteconfiguration of β-chiral primary alcohols. The structures varied from simple aliphatic alcohols to complex cyclic systems and highly substituted sugar derivatives. The NMR-based method was successfully implemented to evaluate 17 compounds and displayed ΔδPM values
Synthese und Charakterisierung chiraler Organogallium- und -aluminiumalkoholate mit intramolekularer Stickstoffstabilisierung. Röntgenstrukturanalyse von Dimethylgallium-(S)-2-dimethylamino-3-methyl-1-butanolat, Dimethylgallium-(S)-2-dimethylamino-3-phenyl-1-propanolat und Dimethylgallium-(R)-2-dimethylamino-1-butanolat
作者:Herbert Schumann、Sonja Wernik、Birgit C. Wassermann、Frank Girgsdies
DOI:10.1016/s0022-328x(00)00767-1
日期:2001.3
The reactions of trimethylgallium and trimethylaluminium with optically active alcohols yield [Me2GaOCH2CHRNMe2]2 [R=Me (S) 6, iPr (S) 7, iBu (S) 8, Bz (S) 9, Et (R:S>90:10) 10] and [Me2AlOCH2CHRNMe2]2 [R=iBu (S) 11, Et (R:S>90:10) 12], respectively. The compounds have been characterized by 1H-,13C-NMR and mass spectroscopy. They undergo a dynamic process with respect to the dissociation and association
Synthesis and application of ligands for the asymmetric addition of organolithium reagents to imines
作者:Catrin A. Jones、Iwan G. Jones、Mushtaq Mulla、Michael North、Lucia Sartori
DOI:10.1039/a702028g
日期:——
Amino acid derived ligands 4d,e are prepared from (S)-valine and (S)-proline respectively, and can be used as chiral ligands during the asymmetricaddition of organolithium reagents to N-arylimines. Ligand 4e, which is prepared by two independent routes, is found to induce addition of organolithium reagents to the si-face of the imines, whilst ligand 4d in common with the previously reported catalysts
Chiral β-dimethylaminoalkylphosphines were prepared starting with amino acids, (S)-alanine, (S)-phenylalanine, (R)-phenylglycine, (S)-valine, and (R)-tert-leucine. The chiral phosphines were found to be highly efficientligands for a nickel catalyzed asymmetric Grignard cross-coupling reaction (38∼94% optical yield).