Hydroxyproline-Derived Pseudoenantiomeric [2.2.1] Bicyclic Phosphines: Asymmetric Synthesis of (+)- and (−)-Pyrrolines

• Published in: Journal of the American Chemical Society Vol. 136; no. 34; pp. 11890 - 11893
• Main Authors: Henry, Christopher E, Xu, Qihai, Fan, Yi Chiao, Martin, Tioga J, Belding, Lee, Dudding, Travis, Kwon, Ohyun
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 27-08-2014
• Subjects: Asymmetry; Bridged Bicyclo Compounds - chemical synthesis; Bridged Bicyclo Compounds - chemistry; Catalysis; Catalysts; Communication; Enrichment; Hydroxyproline - chemistry; Imines; Molecular Structure; Phosphines; Phosphines - chemical synthesis; Phosphines - chemistry; Purification; Pyrroles - chemical synthesis; Pyrroles - chemistry; Stereoisomerism; Synthesis
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja505592h

We have prepared two new diastereoisomeric 2-aza-5-phosphabicyclo[2.2.1]­heptanes from naturally occurring trans-4-hydroxy-l-proline in six chemical operations. These syntheses are concise and highly efficient, with straightforward purification. When we used these chiral phosphines as catalysts for reactions of γ-substituted allenoates with imines, we obtained enantiomerically enriched pyrrolines in good yields with excellent enantioselectivities. These two diastereoisomeric phosphines functioned as pseudoenantiomers, providing their chiral pyrrolines with opposite absolute configurations.