Asymmetric C-C bond forming reactions with chiral crown catalysts derived from D-glucose and D-galactose

New chiral monoaza-15-crown-5 derivatives anellated to methyl-4,6-O-benzylidene-alpha-D-glucopyranoside 2a, 2e, 2g-i and to methyl-4,6-O-benzylidene-alpha-D-galactopyranoside 3a, 3e, 3i have been synthesized. These crown ethers showed significant asymmetric induction as phase transfer catalysts in the Michael addition of 2-nitropropane to chalcone (87% ee), in the Darzens condensation of phenacyl chloride with benzaldehyde (71% ee) and in the self-condensation of phenacyl chloride (64% ee) to give 14. The absolute configurations of (-)-(2R,3S)-epoxy-3-(4-chlorophenyl)-1-phenyl-1-propanone 12 and (-)-4-chloro-(2R,3S)-epoxy- 1,3-diphenyl-1-butanone 14 have also been determined by X-ray diffraction. (C) 1999 Elsevier Science Ltd. All rights reserved.