Addition of Organozincate Reagents to Imines Derived from (S)-1-Phenylethylamine and Ethyl (S)-Valinate—Synthesis of (S)-1-(2-Pyridyl)Alkylamines
摘要:
AbstractTriorganozincates were added to aliphatic aldimines derived from (S)‐1‐phenylethylamine and (S‐valine esters in the presence of boron trifluoride to give secondary amines with low diastereoselectivies. From mixed zincates, most alkyl groups (methyl, ethyl, 1‐heptynyl, but not tert‐butyl) could be transferred. No addition to benzaldimines was observed, but the imines prepared from 2‐pyridinecarboxaldehyde did not require activation by BF3 and underwent selective group transfer from mixed zincates at — 78°C. Excellent diastereoselectivities were observed in the reactions of the 2‐pyridine imine derived from ethyl (S)‐valinate with mixed zincates, in which the methyl group was used as nontransferable ligand, allowing the transfer of alkyl and vinyl groups with excellent to complete selectivity. However, dimethyl(aryl)‐ and dimethyl‐(1‐heptynyl)zincates did not react. (S)‐1‐(2‐Pyridyl)alkylamines were prepared with high optical purity by subsequent removal of the chiral auxiliary.
The reaction of β-amino alcohols with 1,1′-carbonyldiimidazole in dichloromethane is affected by the size of the nitrogen substituent. 1,3-Oxazolidin-2-ones are exclusively obtained from N-H, N-methyl and N-arylmethyl derivatives. O-(1-Imidazolyl)carbonyl derivatives are formed as intermediates from N-[1-(2-pyridyl)alkyl]-(S)-valinol and are mainly or exclusively converted into aziridines in the presence
β-氨基醇与 1,1'-羰基二咪唑在二氯甲烷中的反应受氮取代基大小的影响。1,3-Oxazolidin-2-ones 仅从 NH、N-甲基和 N-芳甲基衍生物中获得。O-(1-咪唑基)羰基衍生物作为中间体由 N-[1-(2-吡啶基)烷基]-(S)-缬氨醇形成,主要或仅在水存在下转化为氮丙啶,尽管环化是被三苯甲基等大的 N 取代基阻碍。
Design and synthesis of enantiopure 1-[1( S )-(2-pyridyl)alkyl]-2( R )-isopropylaziridines, new ligands for asymmetric catalysis
Enantiopure 1-(2-pyridyl)alkyl aziridines were designed as bidentate ligands for asymmetric catalysis. Their synthesis involved the addition of organometallic reagents to the imine prepared from 2-pyridinealdehyde and an enantiopure β-aminoalcohol, followed by cyclisation of the β-aminoalcohol moiety to the aziridine ring. Two such ligands (N–N)* were prepared from (S)-valinol and converted to the