title: Synthesis of ribo-hexopyranoside- and altrose-based azacrown ethers and their application in an asymmetric Michael addition.
abstract: The synthesis of four new ribo-hexopyranoside-based chiral lariat ethers of monoaza-15-crown-5 type and two altropyranoside-based crown ethers were elaborated. Our syntheses utilized the regioselective ring opening of the oxiran moiety of the 2,3-anhydro sugars by nucleophilic reagents to afford the key intermediates. The reaction of methyl-2,3-anhydro-4,6-O-benzylidene-α-D-mannopyranoside with ethanolamine is especially of interest to afford a 3-substituted altropyranoside. One of the ribo-hexopyranoside-based lariat ethers with a 4-methoxyphenyl substituent induced an enantioselectivity of 80% when used as catalyst in the Michael addition of diethyl acetamidomalonate to trans-β-nitrostyrene under phase transfer catalytic conditions.
authors.affiliation: Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, PO Box 91, 1521 Budapest, Hungary.
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Rapi
authors.forename: Péter
authors.initials: P
authors.lastname: Bakó
authors.forename: György
authors.initials: G
authors.lastname: Keglevich
authors.forename: Áron
authors.initials: Á
authors.lastname: Szöllősy
authors.forename: László
authors.initials: L
authors.lastname: Drahos
authors.forename: László
authors.initials: L
authors.lastname: Hegedűs
mesh_terms: D001894:Borohydrides / Q000737:chemistry; D002384:Catalysis; D060326:Chemistry Techniques, Synthetic / Q000379:methods*; D002853:Chromatography, Liquid / Q000379:methods; D043844:Crown Ethers / Q000138:chemical synthesis* / Q000737:chemistry; D006601:Hexoses / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008314:Malonates / Q000737:chemistry; D015394:Molecular Structure; D044367:Phase Transition; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D013343:Styrenes / Q000737:chemistry
chemical_list: D001894:Borohydrides; D043844:Crown Ethers; D006601:Hexoses; D008314:Malonates; D000644:Quaternary Ammonium Compounds; D013343:Styrenes; C550222:tetrabutylammonium borohydride; C030979:diethyl acetamidomalonic acid; C042148:15-crown-5; C011955:beta-nitrostyrene