103. The synthesis and characterization of new optically active 'dimeric' 'pineno'-[4,5]-fused 2,2′-bipyridines linked without spacer or by small spacer groups

Fletcher, Nicholas C. and Keene, F. Richard and Ziegler, Marco and Stoeckli-Evans, Helen and Viebrock, Heiko and Von Zelewsky, Alex (1996) 103. The synthesis and characterization of new optically active 'dimeric' 'pineno'-[4,5]-fused 2,2′-bipyridines linked without spacer or by small spacer groups. Helvetica Chimica Acta, 79 (4). pp. 1192-1202. ISSN 0018-019X

Abstract

Linked chiral bipyridines 2-4 are prepared by combining two optically active 'pineno'-[4,5]-fused 2,2′-bipyridines in a stereoselective reaction (Scheme 1). These potential ligands are new members of the 'chiragen' family, and are characterized by NMR spectroscopy and, in the case of 2 and 3 by single-crystal X-ray analysis. A new synthesis of 'dipineno'-[4,5;4′,5′]-fused 2,2′-bipyridine 8 is described, which, when coupled, gives additional four chiral centres to the analogous 'chiragen' series (→9). Analysis of the CD spectra allowed conformational information about the solution species to be determined.