Asymmetric synthesis of novel C2-symmetric bimorpholines
摘要:
Novel heterocycles-(2S,2'S)-bimorpholine 1 and (3S,3'S)-bimorpholine 2-were synthesised in >98% e.e. starting from tartaric acid ester. (C) 2002 Elsevier Science Ltd. All rights reserved.
C2-Symmetric bimorpholines as chiral ligands in the asymmetric hydrogenation of ketones
摘要:
2,2'-Bimorpholine and 3,3'-bimorpholine were used as chiral ligands in Rh-mediated asymmetric hydride transfer reduction of prochiral aromatic ketones affording corresponding alcohols with good ee (up to 75%). (C) 2003 Elsevier Ltd. All rights reserved.
New N-alkyl-3,3'-bimorpholine derivatives (iPBM) were revealed to be efficient organocatalysts for the asymmetric direct Michael addition of aldehydes to nitroolefins and a vinyl sulfone. In these transformations using iPBM, 1,4-adducts were afforded in high yields, with good to high levels of diastereo- and enantioselectivity. The stereochemical outcome of the reaction could be explained by an acyclic
An anchimeric effect of vicinal dimesylate in the intramolecular nucleophilicsubstitution by amine is described. One sulfonate group of the dimesylate acts as an internal nucleophile and the other as a leaving group, affording meso-bimorpholine in the intramolecular cyclization. ω,ω'-Dimesylate omits this effect and the target compound is obtained with high ee.
描述了连位二甲磺酸酯在胺的分子内亲核取代中的非嵌合效应。二甲磺酸酯的一个磺酸盐基团充当内部亲核试剂,另一个充当离去基团,在分子内环化中提供内消旋双吗啉。ω,ω'-Dimesylate 忽略了这种影响,得到了具有高 ee 的目标化合物。
Synthesis and Use of 3,3′-Bimorpholine Derivatives in Asymmetric Michael Addition and Intramolecular Aldol Reaction
The synthesis of 3,3′-bimorpholine and its N-alkyl derivatives is described. These new diamine derivatives were revealed to be efficient organocatalysts for the asymmetric Michael addition of aldehydes to nitroalkenes with excellent enantioselectivity (up to 90% ee). The potential of these organocatalysts was also demonstrated for the highly enantioselective intramolecularaldolreaction affording