title: Direct chemical synthesis of the beta-mannans: linear and block syntheses of the alternating beta-(1-->3)-beta-(1-->4)-mannan common to Rhodotorula glutinis, Rhodotorula mucilaginosa, and Leptospira biflexa.
abstract: Two stereocontrolled syntheses of a methyl glycoside of an alternating beta-(1-->4)-beta-(1-->3)-mannohexaose, representative of the mannan from Rhodotorula glutinis, Rhodotorula mucilaginosa, and Leptospira biflexa, are described. Both syntheses employ a combination of 4,6-O-benzylidene- and 4,6-O-p-methoxybenzylidene acetal-protected donors to achieve stereocontrolled formation of the beta-mannoside linkage. The first synthesis is a linear one and proceeds with a high degree of stereocontrol throughout and an overall yield of 1.9%. The second synthesis, a block synthesis, makes use of the coupling of two trisaccharides, resulting in a shorter sequence and an overall yield of 4.4%, despite the poor selectivity in the key step.
authors.affiliation: Department of Chemistry, University of Illinois, 845 West Taylor Street, Chicago, Illinois 60607-7061, USA. dcrich@uic.edu
authors.forename: David
authors.initials: D
authors.lastname: Crich
authors.forename: Wenju
authors.initials: W
authors.lastname: Li
authors.forename: Hongmei
authors.initials: H
authors.lastname: Li
mesh_terms: D001597:Benzylidene Compounds / Q000737:chemistry; D002240:Carbohydrate Sequence; D004987:Ethers / Q000737:chemistry; D006027:Glycosides / Q000138:chemical synthesis / Q000737:chemistry; D007919:Leptospira / Q000737:chemistry / Q000378:metabolism*; D008351:Mannans / Q000138:chemical synthesis* / Q000378:metabolism; D008969:Molecular Sequence Data; D012248:Rhodotorula / Q000737:chemistry / Q000378:metabolism*
chemical_list: D001597:Benzylidene Compounds; D004987:Ethers; D006027:Glycosides; D008351:Mannans; C081692:beta-1,4-mannan