Anne-Marie Sepulchre

Synthese de sucres a chaine allongee heptose et octose par c-acylation nucleophile

Abstract The synthesis of extended chain; heptoses and octoses was achieved by nucleophilic C-acylation using carbanions derived from 1,3-dithiane 1 and 2-methyl-1,3-dithiane 10 on 1,2:3,4-di-O-isopropylidene-α- d -galacto-1, 5-hexodialdopyranose 2 . The diastereoisomeric products 3 and 4 or 11 and 12 are formed in different proportion according to the solvent used. 11 was transformed by azidolysis into dithiepane derivatives 14 , 15 and 16 . From the intermediate 12 , the diol 18 , a precursor of lincosamine, was obtained.

Nucleophilic displacement of carbohydrate primary halides with lithio-1, 3-dithiane

Aus den beiden 5-funktionellen Ribofuranosiden (Ia) und (Ib) erhalt man mit 2-Lithio-1,3-dithian (II) das Kondensationsprodukt (III), das zum Aldehyd (IV) verseift und dann zum Carbinol (V) reduziert wird.

Méthode générale de synthèse d'hydrates de carbone à chaîne ramifiée, constituants d'antibiotiques glucidiques

Summary Biological C -acylation (figure 1), can be simulated in vitro by reactions of 2-lithio-1,3-dithian and related carbanion systems on readily available carbohydrate substrates. Treatment of the ketones 3 and 10 with carbanions 1 and 2 yielded 4, 5 and 11, 12 , respectively. These highly functionalised branched dithianyl and methyl-dithianyl derivatives were transformed — employing standard procedures — to the desired carbohydrates 6, 7, 8 and 13, 14 , having as a branched chain: CHO, CH 2 OH, COCH 3 and CH 2 CH 2 groups.

Synthesis of aminocyclitols from l-quinic acid

Abstract A variety of 1,3-diamino and 1,4-diaminocyclitols, manoaminocyclitols, and triaminocyclohexanol have been synthesized starting with the chiral ketone intermediate, 2, derived from l -quinic acid. Reduction of 2 with lithium borohydride afforded two epimeric diols (4 and 5), both of which were transformed by straight-forward but distinctly different chemical procedures into potentially useful aglycons for preparing novel tupes of bioactive, aminocyclitol glycoside antibiotics. The disposition of the substituents at C-1, C-3, C-4, and C-5 in 19 and 37 is identical with that present in the 2-deoxystreptamine nucleus in the naturally occurring antibiotics

Synthese de cetoses a chaine ramifiee dans la serie du d-fructose et du d-psicose

Abstract Stereospecific synthesis of branched-chain 3-C-formyl, 3-C-hydroxymethyl and 3-C-methyl derivatives of d -psicose have been achieved via nucleophilic C-acylation by means of the 1,3-dithian carbanion of 1,2:4,5-di-O-isopropylidene-β- d -erythro-hexo-2,3-diulo-2,6-pyranose 1. Addition of nitromethane to 1 led to d -psicose and d -fructose derivatives 8 and 9.

Synthèse du 5-azido-1,4-di-O-benzyl-5-désoxy-2-O-p-tolylsulfonyl-D-ribitol et du 2-azido-2-désoxy-3,4-O-isopropylidène-1-O-(tétrahydropyrann-2-yl)-5-O-p-tolylsulfonyl-L-arabinitol à partir de la D-ribono-1,4-lactone

Abstract 5-Azido-1,4-di- O -benzyl-5-deoxy-2- O - p -tolylsulfonyl- D -ribitol and 2-azido-2-deoxy-3,4- O -isopropylidene-1- O -(tetrahydropyran-2-yl)-5- O - p -tolylsulfonyl- L -arabinitol have been synthesized from D -ribono-1,4-lactone ( 2 ). In both compounds the functional azide and tosyloxy groups are conveniently located for intramolecular cyclization. The 1,5-lactone acetal 1 was formed in 20% yield besides the expected 1,4-lactone acetal 3 , when 2 was heated with cyclohexanone in the presence of an acid catalyst. Chemical degradation of both lactones 1 and 3 gave derivatives of D -and L -erythrose, respectively.

NUCLEOPHILIC DISPLACEMENT OF CARBOHYDRATE PRIMARY HALIDES WITH LITHIO-1,3-DITHIANE

Aus den beiden 5-funktionellen Ribofuranosiden (Ia) und (Ib) erhalt man mit 2-Lithio-1,3-dithian (II) das Kondensationsprodukt (III), das zum Aldehyd (IV) verseift und dann zum Carbinol (V) reduziert wird.

Synthèse de dérivés pyrrolidiniques. Cyclisation intramoléculaire conduisant au 1,4; 2,5-dianhydro-2,3,4-tri-désoxy-2,4-bis-(p-toluènesulfonamido)-d-thréo-pentitol

Abstract The synthesis of pyrrolidine derivatives has been accomplished by nucleophilic displacement reactions of sulfonic esters of 2,5-anhydro-2,3-dideoxy-2- p -toluene-sulfonamido (or 2-acetamido)- l - erythro -pentitol, using as reagent either sodium azide- N,N -dimethylformamide or sodium azide-acetonitrile. It has been found that the replacement of sulfonyloxy groups of the 1-benzoate-4- p -toluenesulfonate and 1,4-di- p -toluenesulfonate is fairly rapid. Catalytic hydrogenation of the monoazides at C-1 or C-4, followed by sulfonylation, afforded in situ 1,4:2,5-dianhydro-2,3,4-trideoxy-2,4-bis-( p -toluenesulfonamido)- d - threo -pentitol.

Synthesis and X-ray crystallographic studies of dithiepan derivatives of carbohydrates

Nucleophilic addition of 2-lithio-2-methyl-1,3-dithian to the dialdehyde (2) gives the two diastereo-isomers (3) and (7) was transformed into a new class of carbohydrate dithiepan derivatives (11)–(13).