Enantiomerically pure chiral phenazino-crown ethers:: synthesis, preliminary circular dichroism spectroscopic studies and complexes with the enantiomers of 1-arethyl ammonium salts

Enantiomerically pure chiral crown ethers containing the phenazine unit [(R,R)-2(S,S)-8] were prepared by two types of cyclization reactions. Ligands (R,R)-2, (R,R)-3, (S,S)-4, (R,R)-5, (R,R)-6 and (R,R)-7 were prepared from phenazine-1,9-diol 9 and the appropriate ditosylates (S,S)-10-(S,S)-15 in weak basic conditions with complete inversion of configuration. Ligands (S,S)-2, (S,S)-7 and (S,S)-8, however, were prepared from 1,9-dichlorophenazine 19 and the appropriate diols (S,S)-16(S,S)-18 in strong basic conditions with retention of configuration. Enantiomeric recognition of most of the chiral ligands with alpha-(1-naphthyl)ethylammonium perchlorate (NEA) and alpha-phenylethylammonium perchlorate (PEA) has been studied by CD spectroscopy. (C) 1999 Elsevier Science Ltd. All rights reserved.