THE SYNTHESIS AND CHARACTERIZATION OF NEW OPTICALLY-ACTIVE DIMERIC PINENO-[4,5]-FUSED 2,2'-BIPYRIDINES LINKED WITHOUT SPACER OR BY SMALL SPACER GROUPS

Linked chiral bipyridines 2-4 are prepared by combining two optically active 'pineno'-[4,5]-fused 2,2'-bipyridines in a stereoselective reac tion (Scheme 1). These potential ligands are new members of the 'chira gen' family, and are characterized by NMR spectroscopy and, in the cas e of 2 and 3 by single-crystal X-ray analysis. A new synthesis of 'dip ineno'-[4,5;4',5']-fused 2,2'-bipyridine 8 is described, which, when c oupled, gives additional four chiral centres to the analogous 'chirage n' series (-->9). Analysis of the CD spectra allowed conformational in formation about the solution species to be determined.