Is the A-ring of sparteine essential for high enantioselectivity in the asymmetric lithiation-substitution of N-Boc-pyrrolidine?
The simplest chiral portion of sparteine, N,N'-dimethyl-2-endo-methylbispidine, was prepared and evaluated in the asymmetric lithiation-substitution of N-Boc-pyrrolidine. The results indicate that the complete A-ring of sparteine is essential for high levels of asymmetric induction. DFT-QSSR analyses of the diamine/Li(+) complexes and DFT calculations of the pertinent i-PrLi/diamine/N-Boc-pyrrolidine complexes are predictive and provide complementary pictures of the stereochemical features critical to this transformation.
Phuan
Puay-Wah
PW
Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA.
Ianni
James C
JC
Kozlowski
Marisa C
MC
D003959:Diamines / Q000737:chemistry; D008094:Lithium / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000737:chemistry*; D011759:Pyrrolidines / Q000737:chemistry*; D021281:Quantitative Structure-Activity Relationship; D013034:Sparteine / Q000737:chemistry*; D013237:Stereoisomerism; D013816:Thermodynamics
D003959:Diamines; D009942:Organometallic Compounds; D011759:Pyrrolidines; D013034:Sparteine; D008094:Lithium