J. Cleophax

Solvent-Free Synthesis of Decyl D-Glycopyranosides Under Focused Microwave Irradiation

Abstract A three step microwave assisted solvent-free synthesis of decyl D-glucopyranoside with 1-decanol was established for D-glucose and extended to D-galactose, D-mannose and N-troc-D-glucosamine with 70% average overall yield for the three steps (peracetylation, glycosylation and saponification). Rate enhancements and reduction of the reaction time were observed for the two last steps carried out under microwave irradiation when compared to conventional heating in the same conditions.

Liquid crystalline 5,6-O-acetals of L-galactono-1,4-lactone prepared by a microwave irradiation on montmorillonite

Abstract Acetal derivatives of L-galactono-1,4-lactone showing thermotropic liquid crystalline properties were synthesized without sovent in the presence of dry montmorillonite KSF using microwave irradiation.

Synthesis of benzoyl and dodecanoyl derivatives from protected carbohydrates under focused microwave irradiation

Abstract A microwave assisted phase transfer catalyzed transesterification in basic medium with methyl benzoate was studied for several carbohydrates. Small amounts of DMF were necessary to provide good yields (96-76%) within 15 minutes. This method was extended to the synthesis of dodecanoyl derivatives with 63–100% global yields within 15 to 30 minutes. Rate enhancements when compared to conventional heating in the same conditions and specific microwave activation were mostly cvidenced when fatty compounds (less reactive) were involved.

Stereoselective synthesis of 6-deoxy and 3,6-dideoxy-D-myo-inositol precursors of deoxy-myo-inositol phosphate analogues from D-galactose

The synthesis of chiral protected D-6-deoxy-myo-inositol derivatives from D-galactose is described. Ferrier rearrangement of hexenogalactopyranosides has been employed to produce the corresponding 6-deoxy-cyclohexanone polyols. The stereoselectivity of the carbocyclic transformation was discussed on the basis of the experimental data and a mechanism has been proposed. From deoxy-inososes, the access to a variety of 6-deoxy and 3,6-dideoxy-myo-inositol was performed to prepare suitable monool, diol and triol precursors for the synthesis of D-deoxy-myo-inositol phosphate analogues.

Chiral synthesis of 3,4-disubstituted 2-azetidinones from (R,R)-(+)-tartaric acid

Abstract A novel route Is described for the enantioselective synthesis of 2-azetidinones 24 and 25 from (R,R)-(+)-tartaric acid. Monomethylation, monobenzylation of 2 and the use of site specific pig liver esterase (PLE) to produce 6 and 7 are the key steps in the sequence.

Synthese de derives de la purpurosamine C,composant de la gentamicine C1a

Abstract The synthesis of derivatives of purpurosaimine C and epi -purpurosamine C is described, from methyl 2,3,4,6-tetra-O-methylsulphonyl-α- d -galacto and glucopyranosides 2 and 3 by reaction with azide ion to give diazides 4 and 5 , transformed in a series of reactions via epoxides 6 and 7 into the corresponding olefines 16 and 17 , thermal rearrangement to give diazides 18 and 19 , which were transformed into the methyl glycosides 27 and 29 and mercaptolysis with ethanethiol followed by N -acetylation, gave 2,6-diacetamido-2,3,4,6-tetradeoxy- d -erythro-hexose diethyl dithioacetal 30 (identical with authentic 30 prepared from gentamicin C 1a )and 2,6-diacetamido-2,3,4,6-tetradeoxy- d - threo -hexose diethyl dithioacetal 31 , an enantiomer of a mercaptolysis product of dihydrosisomicin.

Synthese de derives de la tobrosamine par addition d'acide hydrazoique sur un systeme enonique dans la serie hydrate de carbone

Abstract Derivatives of a new diaminotrideoxy- d - ribo -hexopyranose, a component of the antibiotic tobramycin, have been prepared by addition of the elements of hydrazoic acid to the α, β-unsaturated ketone 8 . After 5 min only the kinetically favored product 13 was observed, which is gradually transformed into the thermodynamically more-stable substance 20 . The equilibrium mixture after 5 hours contained d - erythro and d - threo isomers 20 and 13 in the ratio 6:4 The d - erythro azide 20 was converted into the derivatives of di- N -acetyl tobrosamine.

STEREOSELECTIVE SYNTHESIS OF INOSITOL MONO, BIS AND TRISPHOSPHATE ANALOGUES FROM 6-DEOXY-D-INOSITOL PRECURSORS

Abstract The synthesis of opticaly pure deoxy- myo -inositol mono, bis and trisphosphate analogues is described from 4- O -benzyl-2,3-di- O -cyclohexylidene-6-deoxy- myo -inositol and corresponding 1,5 epimer chiro -inositol. These precursors, which derive from galactose, are used to accede to a variety of cyclitol intermediates employing protection/deprotection sequence. The phosphorylation procedure was performed to produce free and original substituted phosphate derivatives aimed to be incorporated through the lipidic cell membrane for in vivo evaluation.

Solvent-free benzylation of polyols by phase-transfer catalysis or supported reagent methods

Abstract Solvent-free techniques were successfully and efficiently applied under mild conditions to the perbenzylation of methyl α- d -glucopyranoside and methyl 6-bromo(and 6-chloro)-6-deoxy-α- d -glucopyranoside, and to the selective monobenzylation of diethyl (R,R)-tartrate. Selective 2-O- or 3-O-benzylation of methyl 4,6-O-benzylidene-α- d -galactopyranoside, requiring CH2Cl2 as solvent, was observed depending on the nature of the ammonium catalyst.

Stereoselective synthesis of myo-inositol-1,3,4,5-tetrakisphosphate analogues from 6-deoxy d-inositol precursors

Abstract The synthesis of 6-deoxy-D-myo-inositol-1,3,4,5-tetrakisphosphates is described. The access to opticaly pure Ins(1,3,4,5)P4 analogues was carried out from deoxy myo inositol precursors derived from d -galactose. Modification of Ins(1,3,4,5)P4 analogues by lipophilic substituents has been investigated in order to produce neutral phosphate derivatives aimed to be incorporated in cell membrane for in vivo evaluation.