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  • Hydroxyproline-derived pseudoenantiomeric [2.2.1] bicyclic phosphines: asymmetric synthesis of (+)- and (-)-pyrrolines.

Hydroxyproline-derived pseudoenantiomeric [2.2.1] bicyclic phosphines: asymmetric synthesis of (+)- and (-)-pyrrolines.

Journal of the American Chemical Society (2014-08-08)
Christopher E Henry, Qihai Xu, Yi Chiao Fan, Tioga J Martin, Lee Belding, Travis Dudding, Ohyun Kwon
ABSTRACT

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.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Exo-2-Naphthyl Kwon [2.2.1] Bicyclic Phosphine
Sigma-Aldrich
Exo-1-Naphthyl Kwon [2.2.1] Bicyclic Phosphine
Sigma-Aldrich
Endo-4-Methoxyphenyl Kwon [2.2.1] Bicyclic Phosphine
Sigma-Aldrich
Endo-Phenyl Kwon [2.2.1] Bicyclic Phosphine, 95% (HPLC)
Sigma-Aldrich
Endo-1-Naphthyl Kwon [2.2.1] Bicyclic Phosphine
Sigma-Aldrich
Exo-Phenyl Kwon [2.2.1] Bicyclic Phosphine, 95% (HPLC)
Sigma-Aldrich
Exo-4-anisole Kwon [2.2.1] bicyclic phosphine