title: Regioselectively trisilylated hexopyranosides through homogeneously catalyzed silane alcoholysis.
abstract: The iridium complex [Ir(COD)(PPh3)2]+ SbF6- reacts with tert-butyldimethylsilane in DMA to form [IrH2(Sol)2(PPh3)2]+ SbF6-, which is an active catalyst for the regioselective di- and trisilylation of a series of representative methyl hexopyranosides, beta-1,6-anhydrohexopyranosides and 1,3,5-O-methylidene inositol. The corresponding 2,3,6- and 2,4,6-silylated glycosides are obtained in a separable mixture of 47-89% (2,3,6-isomers) and 9-25% (2,4,6-isomers) yield in a single-pot reaction. The 2,4-disilylated derivatives of mannosan, galactosan, and 1,3,5-O-methylidene inositol as well as persilylated levoglucosan are accessible in >85% yield by this method. The homogeneous nature of the catalysts is a prerequisite for the effective di-/trisilylation, as nanoparticle colloid catalysts generated in situ from Pd2(dba)3 (approximately 1.5 nm average particle size) or Ru2Cl5(MeCN)7 (approximately 0.65 nm average particle size) result in only low yields.
authors.affiliation: The Guelph-Waterloo Centre for Graduate Work in Chemistry (GWC), Department of Chemistry, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
authors.forename: Mee-Kyung
authors.initials: MK
authors.lastname: Chung
authors.forename: Marcel
authors.initials: M
authors.lastname: Schlaf
mesh_terms: D002384:Catalysis; D005690:Galactose / Q000031:analogs & derivatives / Q000737:chemistry; D006027:Glycosides / Q000138:chemical synthesis* / Q000737:chemistry; D006601:Hexoses / Q000138:chemical synthesis* / Q000737:chemistry; D007294:Inositol / Q000031:analogs & derivatives; D007495:Iridium / Q000737:chemistry; D008358:Mannose / Q000031:analogs & derivatives / Q000737:chemistry; D049329:Nanostructures / Q000737:chemistry; D012821:Silanes / Q000737:chemistry*; D014297:Trimethylsilyl Compounds / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D006027:Glycosides; D006601:Hexoses; D012821:Silanes; D014297:Trimethylsilyl Compounds; C458759:galactosan; C458739:mannosan; D007495:Iridium; D007294:Inositol; D008358:Mannose; D005690:Galactose