Stereoselective C9 carbon-carbon couplings of quinine: synthesis and conformational analysis of new C2-symmetric dimers.
An unexpected stereoselective direct dimerization occurred when 9-quinine halide was treated with butyllithium. The reaction of either (9S)- or (9R)-chloroquinine gave the same C2-symmetric dimer with 9R configuration (X-ray structure). A tentative mechanism involving radical recombination is discussed. This highly congested dimer forms two atropisomers, and their reversible interconversion was studied by NMR. Another C2-symmetric (9S)-quinine dimer connected solely by carbon-carbon bonds was obtained by the stereoselective coupling of bis(arylbromomagnesium) derivative with (9S)-chloroquinine.
Boratyński
Przemysław J
PJ
Department of Organic Chemistry and Institute of Physical and Theoretical Chemistry, Faculty of Chemistry, Wrocław University of Technology, 50-370 Wrocław, Poland.
Turowska-Tyrk
Ilona
I
Skarzewski
Jacek
J
D002244:Carbon / Q000737:chemistry*; D002738:Chloroquine / Q000031:analogs & derivatives / Q000737:chemistry; D018360:Crystallography, X-Ray; D019281:Dimerization; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000737:chemistry; D011803:Quinine / Q000031:analogs & derivatives / Q000138:chemical synthesis* / Q000737:chemistry*; D013237:Stereoisomerism
D009942:Organometallic Compounds; C046771:butyllithium; D002244:Carbon; D002738:Chloroquine; D011803:Quinine