H. M. Zuurmond

Synthesis of Carbohydrate-Antigenic Structures of Mycobacterium Tuberculosis using an Iodonium Ion Promoted Glycosidation Approach

ABSTRACT Analogues of the phenol-phthiocerol glycoside la of Mycobacterium tuberculosis were synthesized starting from properly protected rhamnose and fucose ethyl thioglycosides. A recently developed iodonium ion promoted glycosidation procedure proved to be very efficient for the preparation of 3-aminopropyl 3-O-(α-L-rhamnopyranosyl)-2-O-methyl-α-L-rhamnopyranoside (2), 3-aminopropyl 3-O-[3-O-(2,3,4-tri-O-methyl-α-L-fucopyranosyl)-α-L-rhamnopyranosyl]-2-O-methyl-α-L-rhamnopyranoside (3) and 3-aminopropyl 3-O-(2,3,4-tri-O-methyl-α-L-fucopyranosyl)-α-L-rhamnopyranoside (4).

A stereospecific approach towards the synthesis of 2-deoxy α- and β-glycosides based on a 1,2-ethyl (phenyl) thio group migration

Abstract Iodonium ion (NIS/TfOH)-assisted glycosylation of a sugar acceptor with properly protected ethyl (phenyl) 2- O -phenoxythiocarbonyl 1-thio-β-D-gluco- or 1-thio-α-D-mannopyranoside donors gives the respective 1,2- trans linked 2′-ethyl (phenyl) thio-2′-deoxy-α-D-manno- or β-D-glucopyranosides.

Iodonium-Promoted Glycosylations with Phenyl Selenoglycosides

Abstract Fully benzylated or benzoylated phenyl selenoglycosides can be activated by the promoters iodonium di-sym-collidine perchlorate (IDCP) or N-iodosuccinimide and catalytic triflic acid (NIS/TfOH). The potential of the iodonium ion-mediated glycosylations with phenyl selenoglycosides is illustrated in the chemoselective synthesis of 1,2-cis-and 1,2-trans linked disaccharides.

Iodonium ion-assisted synthesis of a haptenic tetrasaccharide fragment corresponding to the inner cell-wall glycopeptidolipid of Mycobacterium avium serotype 4

Condensation of ethyl 2,4-di-O-benzoyl-1-thio-alpha-L-rhamnopyranoside with ethyl 3-O-benzyl-4-O-chloroacetyl-2-O-methyl-1-thio-beta-L-fucopyranoside in the presence of iodonium di-sym-collidine perchlorate afforded exclusively ethyl 2,4-di-O-benzoyl-3-O-(3-O-benzyl-4-O- chloroacetyl-2-O-methyl-alpha-L-fucopyranosyl)-1-thio-alpha-L-rhamnop yra noside. This disaccharide derivative was extended at C-1 with 3-benzyloxycarbonylaminopropyl 6-deoxy-3,4-O-isopropylidene-alpha-L- talopyranoside, using N-iodosuccinimide and triflic acid as the catalyst, to furnish 3-benzyloxycarbonylaminopropyl 6-deoxy-2-O-[2,4-di-O-benzoyl-3-O-(3-O-benzyl-4-O-chloroacetyl-2-O-me thy l- alpha-L-fucopyranosyl)-alpha-L-rhamnopyranosyl]-3,4-O-isopropylidene-alp ha-L- talopyranoside (20). Selective removal of the chloroacetyl group from 20, followed by condensation with ethyl 2,3-di-O-benzoyl-4-O-methyl-1-thio-alpha-L- rhamnopyranoside in the presence of the same thiophilic promoter, yielded a fully protected tetrasaccharide derivative. Deprotection of the latter gave the target compound 3-aminopropyl 6-deoxy-2-O-[3-O-[2-O- methyl-(4-O-methyl-alpha-L-rhamnopyranosyl)-alpha-L-fucopyranosyl]-alpha -L- rhamnopyranosyl]-alpha-L-talopyranoside (1).

Stereospecific 1,2-ethyl(phenyl)thio group migration in sugars : stereocontrolled synthesis of precursors to α- and β-2-deoxyglycosides

Abstract Iodonium ion (NIS/TfOH, cat.) assisted glycosylation of a sugar acceptor with properly protected enthyl(phenyl)-2-O-phenoxythiocarbonyl 1-thio-β- d -gluco- or 1-thio-α- d -mannopyranoside donors gives the respective 1,2-trans linked 2′-ethyl(phenyl)thio-2′-deoxy-α- d -manno- or β- d -glucopyranosides.

Application of Phenyl 1-Selenoglycosides in the Synthesis of a Cell-Wall Tetrameric Fragment of Proteus Vulgaris Strain 5/43

Abstract DAST-assisted rearrangement of 3-O-allyl-4-O-benzyl-α-l-rhamnopyranosyl azide followed by treatment of the generated fluorides with ethanethiol and BF3·OEt2 gave glycosyl donor ethyl 3-O-allyl-2-azido-4-O-benzyl-2,6-dideoxy-1-thio-α/β-l-glucopyranoside. Stereoselective glycosylation of methyl 4,6-O-benzylidene-2-deoxy-2-phthalimido-β-D-glucopyranoside with ethyl 3-O-allyl-2-azido-4-O-benzyl-2,6-dideoxy-1-thio-α/β-l-glucopyranoside, under the agency of NIS/TfOH afforded methyl 3-O-(3-O-allyl-2-azido-4-O-benzyl-2,6-dideoxy-α-l-glucopyranosyl)-4,6-O-benzyli-dene-2-deoxy-2-phthalimido-β-D-glucopyranoside. Removal of the allyl function of the latter dimer, followed by condensation with properly protected 2-azido-2-deoxy-glucosyl donors, in the presence of suitable promoters, yielded selectively methyl 3-O-(3-O-[6-O-acetyl-2-azido-3,4-di-O-benzyl-2-deoxy-α-D-glucopyranosyl]-2-azido-4-O-benzyl-2,6-dideoxy-α-l-glucopyranosyl)-4,6-O-benzylidene-2-deoxy-2-phthalimido-β-D-glucopyranoside. Deacetylation and ...

An Approach to the Synthesis of Four Rhodomicrobium Vannielii Lipid a Analogues

Abstract The preparation of four Rh. Vannielii Lipid A analogues (i.e. compounds 22, 23, 30 and 33) is described. Non-neighbouring group supported introduction of the β-glycosidic linkages was performed by coupling the mannopyranosyl bromide 2 and the 2-azido-2-deoxy-glucopyranosyl bromides 10 and 13 with the suitably protected glycosyl acceptors 3, 4 and 5 in the presence of a heterogeneous silver catalyst, to give compounds 6, 7, 14 and 24, respectively. Selective removal of the ally1 group and reduction of the azido functions followed by several O,N-acylation steps afforded, after complete deblocking, the tri-and disaccharide Rh. Vannielii Lipid A analogues 22, 23, 30 and 33.