Catalytic Asymmetric Synthesis of Piperidine Derivatives through the [4 + 2] Annulation of Imines with Allenes
作者:Ryan P. Wurz、Gregory C. Fu
DOI:10.1021/ja053277d
日期:2005.9.1
there has been only very limited progress in achieving asymmetric catalysis with chiral phosphines. In this report, the first highly enantioselective variant of the Kwon annulation of imines with allenes is described. Thus, C2-symmetric chiral phosphepine 1 serves as an effective catalyst for this powerful process, furnishing an array of functionalized piperidine derivatives with very good stereoselectivity
Chiral aminophosphines derived from hydroxyproline and their application in allene–imine [4 + 2] annulation
作者:San N. Khong、Changmin Xie、Xinyi Wang、Hao Tan、Ohyun Kwon
DOI:10.1038/s41429-019-0181-0
日期:2019.6
A robust synthetic route from l-hydroxyproline (l-Hyp) to phosphines has established an expandable library of six chiral aminophosphines, which were then applied to the phosphine-catalyzed [4 + 2] allene–imine annulation. The enantioinduction in the annulations—induced by a purely steric effect—were moderate (up to 57% ee). A switch of the reaction site from the γ- to the β′-carbon atom of the allenoate
R-aplexone, methods of preparing R-aplexone, or aplexone substantially free of its S-stereoisomer are disclosed. Methods of using R-aplexone or a pharmaceutically acceptable salt or solvate thereof to treat and/or prevent disease are disclosed. Methods of preparing 6-substituted tetrahydropyridine motifs with high enantiomeric excess are also disclosed.
Catalytic Enantioselective Synthesis of Guvacine Derivatives through [4 + 2] Annulations of Imines with α-Methylallenoates
作者:Qihai Xu、Nathan J. Dupper、Andrew J. Smaligo、Yi Chiao Fan、Lingchao Cai、Zhiming Wang、Adam D. Langenbacher、Jau-Nian Chen、Ohyun Kwon
DOI:10.1021/acs.orglett.8b02489
日期:2018.10.5
These HypPhos catalysts were assembled from trans-4-hydroxyproline, with the modular nature of the synthesis allowing variations of the exocyclic P and N substituents. Among them, exo-(p-anisyl)-HypPhos was most efficacious for [4 + 2] annulations between ethyl α-methylallenoate and imines. Through this method, (R)-aplexone was identified as being responsible for the decrease in the cellular levels
P-手性[2.2.1]双环膦(HypPhos催化剂)已应用于α-烷基联烯酸酯和亚胺之间的反应,生产鳄梨毒肽衍生物。这些 HypPhos 催化剂由反式-4-羟基脯氨酸组装而成,合成的模块化性质允许环外 P 和 N 取代基的变化。其中, exo -(对茴香基)-HypPhos 对于 α-甲基联烯酸乙酯和亚胺之间的 [4 + 2] 成环最有效。通过这种方法,( R )-aplexone 被确定为细胞胆固醇水平降低的原因。