112137-99-2Relevant articles and documents
β-Amino alcohols derived from (1R,2S)-norephedrine and (1S,2S)-pseudonorephedrine as catalysts in the asymmetric addition of diethylzinc to aldehydes
Parrott II, Raleigh W.,Hitchcock, Shawn R.
, p. 19 - 26 (2008/09/16)
A family of N-alkylnorephedrine and N-alkylpseudonorephedrine derived ligands were prepared and applied in the asymmetric alkylation of benzaldehyde using diethylzinc. The absolute configuration of the addition product was directed primarily by the benzylic position of the Ephedra alkaloid, while the magnitude of the enantiomeric ratio was heavily influenced by the nitrogen substituent. However, sterically demanding substituents at the nitrogen position caused the enantioselectivity to be the same for the two diastereomeric systems. Among the ligands that were prepared, it was determined that the N-cyclooctylpseudonorephedrine derivative 7b yielded the highest enantiomeric ratios (87.5:12.5 to 91.0:9.0) when applied in the catalytic asymmetric addition of diethylzinc to aldehydes.
Dimethylzinc-mediated, enantioselective synthesis of propargylic amines
Zani, Lorenzo,Eichhorn, Torsten,Bolm, Carsten
, p. 2587 - 2600 (2008/04/01)
A one-pot, enantioselective synthesis of N-aryl propargylic amines, using alkynylation reagents obtained from dimethylzinc and terminal acetylenes in combination with various aldehydes and o-methoxyaniline as starting materials, has been developed. Enanti
Preparation of chiral phosphorus(V) reagents and their uses with borane in the enantioselective reduction of ketones
Chen, Guo-Hsian
, p. 797 - 810 (2007/10/03)
Chiral pentavalent phosphorus reagents 5-17 were prepared from POCl3 and ephedrine (or the related α-amino alcohols), followed by substitution with nucleophiles of phenylmagnesium bromide, alcohols, amines, diamines and triamines. The substitution reactions occurred in a stereospecific manner with retention of the configuration at the phosphorus center. The structures of these phosphorus(V) reagents were determined by spectral methods and verified by X-ray diffraction in several instances. These phosphorus(V) reagents were used with borane/dimethylsulfide complex in the enantioselective reduction of aromatic, aliphatic and heterocyclic ketones. The phosphorus(V) reagents likely functioned as Lewis bases to react with borane, forming in situ zwitterionic species as the chiral reducing agents. The reactions were generally carried out at 0 °C in tetrahydrofuran solution with a molar ratio of ketone/borane/phosphoramidate = 1:1:0.2 to afford secondary alcohols with modest enantioselectivity, up to 67% ee in the reduction of 4′-methylacetophenone.