title: Aluminum triflate catalyzed tandem reactions of D-galactal: toward chiral benzopyrans, chromenes, and chromans.
abstract: 3,4,6-Tri-O-acetyl-D-galactal is selectively converted into 1-O-aryl-2-deoxy derivatives or chiral bridged benzopyrans under Al(OTf)3 catalysis, depending on reaction conditions. The benzopyrans react with Al(OTf)3/acetic anhydride in ring-opening reactions in the absence or presence of acetic acid to selectively produce chiral chromenes or chromans, respectively, in high yields.
authors.affiliation: Research Centre for Synthesis and Catalysis, Department of Chemistry, University of Johannesburg , P.O. Box 524, Auckland Park 2006, South Africa.
authors.forename: Sandile B
authors.initials: SB
authors.lastname: Simelane
authors.forename: Henok H
authors.initials: HH
authors.lastname: Kinfe
authors.forename: Alfred
authors.initials: A
authors.lastname: Muller
authors.forename: D Bradley G
authors.initials: DB
authors.lastname: Williams
mesh_terms: D001578:Benzopyrans / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D002839:Chromans / Q000138:chemical synthesis* / Q000737:chemistry; D005690:Galactose / Q000031:analogs & derivatives* / Q000737:chemistry; D008698:Mesylates / Q000737:chemistry*; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: C000598268:3,4,6-tri-O-acetyl-D-galactal; D001578:Benzopyrans; D002839:Chromans; D008698:Mesylates; C002038:galactal; C012077:trifluoromethanesulfonic acid; D005690:Galactose