Developing Ru-Catalysts for Asymmetric Transfer Hydrogenation of Acyclic Imines
作者:Dongxu He、Chen Xu、Xiangyou Xing
DOI:10.1021/acs.orglett.2c03385
日期:2022.11.18
Asymmetric transferhydrogenation (ATH) of acyclic imines has been rarely reported by using Ru-based catalysts. In this manuscript, employing Ru-catalysts with minimal stereogenicity in combination with formic acid/triethylamine as the hydrogen donor enables a highly efficient ATH of N-diphenylphosphinyl acyclic imines. These substrates that include various aryl alkyl and heteroaryl alkylsubstituted imines
使用 Ru 基催化剂很少报道无环亚胺的不对称转移氢化 (ATH)。在这份手稿中,使用具有最小立体异构性的 Ru 催化剂与甲酸/三乙胺作为氢供体相结合,可以实现N-二苯基膦基无环亚胺的高效 ATH 。这些包含各种芳基烷基和杂芳基烷基取代亚胺的底物都与该催化体系相容,并以优异的对映体过量 (ee's) 和产率获得相应的还原胺。
Aromatic motifs in the design of Ephedra ligands for application in the asymmetric addition of diethylzinc to aldehydes and diphenylphosphinoylimines
作者:Sucharita Banerjee、Anthony J. Camodeca、Gregory G. Griffin、Christopher G. Hamaker、Shawn R. Hitchcock
DOI:10.1016/j.tetasy.2010.02.026
日期:2010.3
Using N-benzylephedrine as a model, a collection of N-arylmethylephedrine derivatives has been prepared. These derivatives were prepared by treatment of ephedrine with selected aldehydes to create oxazolidines 8a-e. Reduction of the oxazolidines with lithium aluminum hydride afforded the target beta-amino alcohols 9a-e. When applied in the catalytic asymmetric addition of diethylzinc to aldehydes and diphenylphosphinoylimines, the derivatives yielded product enantioselectivities that were comparable to those of N-benzylephedrine. An N-cyclohexylmethylephedrine derivative was also prepared: this 13-aminoalcohol did not perform well in the catalytic addition of diethylzinc to 2-naphthaldehyde, thus suggesting that the aromatic motif is important in terms of maintaining a reasonable level of asymmetric induction. Finally, N-benzyl-N-methyl-2-amino-1,2-diphenyl-1-ethanol, an analogue of the N-benzylephedrine derivative, was prepared. This compound yielded comparable enantioselectivities in the catalytic asymmetric addition when employed as a ligand. (C) 2010 Elsevier Ltd. All rights reserved.