SYNTHESIS AND CRYSTAL-STRUCTURE OF CHIRAL BIFUNCTIONAL HELICENES WITHPI-DEFICIENT PYRIDINE AND PI-EXCESSIVE THIOPHENE UNITS

Both enantiomers of new bifunctional helicenes constructed from pi-exc essive 2-(hydroxymethyl)thiophene and pi-deficient pyridine rings have been prepared using (1R,2S,3R,4S)-3-amino-2-hydroxybornane as a chira l auxiliary. The X-ray crystal structure reveals the intermolecular hy drogen bond between the hydroxy group of the helicene and the pyridine nitrogen atom of the adjacent molecule. The non-bonded distance betwe en the nitrogen atom and the oxygen atom is 2.72 Angstrom, and the int erplanar angle between the terminal rings is 45.3 degrees. Copyright ( C) 1996 Elsevier Science Ltd