Dérivés C‐glycosyliques. XXIV. Glycosyl‐4‐thiazoles

Tronchet, J. M. J.; Eder, Hansjörg

doi:10.1002/hlca.19750580532

Cited by 10 publications

(7 citation statements)

References 13 publications

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“…Le derive de thiosucre 1 [3] possede d priori trois sites oxydables: l'atome de soufre, l'atome de carbone C(5) et, a un moindre degre, le groupement methyline benzylique. Selon l'agent oxydant utilisk [3], on peut oxyder soit simultankment sur l'atome de soufre et en C ( 5 ) pour obtenir 4 (RuO,), soit specifiquement en C(5) en formant le cetosucre 3 (reactif de Moffatt [4]), soit specifiquement sur l'atome de soufre pour obtenir la sulfone correspondante 8 (acide m-chloroperbenzolque). Nous dtcrivons ci-dessous d'autres exemples d'oxydation conduisant aux sulfoxydes 7 et 9 et a la sulfone 10.…”

Section: Discussionunclassified

“…Nous dtcrivons ci-dessous d'autres exemples d'oxydation conduisant aux sulfoxydes 7 et 9 et a la sulfone 10. De plus le cetosucre 3, intermediaire de synthese tres riche [l] [5], peut &re rkgioselectivement monochlore en 5 ou dichlore en 6 [3], alors qu'a priori le carbone C(4) et le groupement methyline benzylique sont l'un et l'autre des candidats I) Thiosucres IV; 111: [l].…”

Section: Discussionunclassified

“…(1) Benzylsulfonyl-6-dichloro-6,6-ddsoxy-6-0-isopropylid2ne-1,2-O-mdthyl-3-a -D-xylo-hexofurunnosulose-5 (10). A une solution de 6 [3] (602 mg, 1,48 mmol) dans CHzCl2 ( 5 ml), on ajoute goutte i goutte B 0" sous agitation une solution d'acide m-chloroperbenzoique a 80% (800 mg, 4,17 mmol) dans CH2C12 (25 ml). Aprts 20 min i 0" et 2 h i 20°, la rtaction est terminCe (CCM.).…”

Section: Gdnpralitps Voir [Is] O-acptyl-5-s-benzyl-6-o-isopropylid~unclassified

“…Une alternative a cette hypothbe serait qu'une liaison S=O eclipse la liaison C(5)-C(6) dans chacun de ces composes. L'oxydation de 3 par l'acide m-chloroperbenzolque conduit, avec un excellent contr6le stoechiomktrique, soit a 4 [3], soit au mClange ( 1 : 1) des isomeres de 9 (89%), inseparables et presentant des spectres de 'H-RMN. ne differant que par la valeur de 6 H-C(4).…”

unclassified

“…Le groupement carbonyle de 3 active les positions C(4) et C (6), alors que l'atome de soufre active C(6) et le groupe methylhe benzylique. MalgrC ses trois sites potentiels d'halogknation, 3 est converti spkcifiquement en 5 [3]. Par contre, lorsqu'on traite 1 par le mCme reactif dans un tube de RMN., on peut mettre en evidence la formation d'un melange complexe de composes provenant d'halogenations en C (6) et sur le groupement methylhe benzylique, sans contr6le stoechiometrique ni regioselectivite.…”

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Oxydations et halogénations régiosélectives et réactions carbéniques de dérivés de sucres portant un groupement thioéther

Tronchet

Eder

1980

Helvetica Chimica Acta

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Regioselective Oxidations, Regioselective Halogenations and Carbene Reactions of Sugar Derivatives Bearing a Thioether Group Regioselective stoechiometrically controlled procedures are described for the oxidation of thiosugars either at the sulfur atom (to sulfoxides or sulfones) or at a hydroxymethylene group (to ketosugars). Ruthenium tetraoxide reacted at both sites. Chloration (SO2Cl2) of β‐ketothioether sugar derivative 3 took place exclusively at C(6). Evidence is given that a chlorosulfonium intermediate C was formed when the dichloroketothiosugar derivative 6 was treated with SO2Cl2. The carbene generated from the tosylhydrazone 16 rearranged to the enoses 17–20, the migrating group coming in equal proportions from C(4) and C(6). Some stereochemical aspects of these reactions are discussed.

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Section: Discussionunclassified

Section: Gdnpralitps Voir [Is] O-acptyl-5-s-benzyl-6-o-isopropylid~unclassified

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Oxydations et halogénations régiosélectives et réactions carbéniques de dérivés de sucres portant un groupement thioéther

Tronchet

Eder

1980

Helvetica Chimica Acta

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Oxidation of Alcohols to Carbonyl Compounds via Alkoxysulfonium Ylides: TheMoffatt,Swern, and Related Oxidations

Tidwell

1990

Organic Reactions

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The use of dimethyl sulfoxide as an oxidizing agent began with the discoveries by Kornblum and co‐workers that certain α‐bromo ketones were converted into glyoxals under mild conditions by treatment with dimethyl sulfoxide, and that primary tosylates such as n ‐octyl tosylate were converted into the corresponding aldehydes using dimethyl sulfoxide and sodium bicarbonate at 150° for 3 minutes. The initial step of the reactions involves a displacement by dimethyl sulfoxide giving an alkoxysulfonium ion and this species undergoes a 1,2 elimination assisted by base to give the carbonyl product A few years later it was discovered that alcohols were oxidized at room temperature to carbonyl compounds by dimethyl sulfoxide, dicyclohexylcarbodiimide (DCC), and phosphoric acid. This reaction was immediately recognized as an effective and mild procedure for sensitive substrates, and the extensive studies by this group and the development of alternative variations elsewhere have been the subject of several earlier reviews. The course of the Moffatt procedure is summarized. The key intermediate in this process is the oxysulfonium ylide, which appears to be common to all of the variations of dimethyl sulfoxide oxidations, and which reacts intramolecularly to give the products. Other related procedures that were soon developed utilize dimethyl sulfoxide activated by acetic anhydride, phosphorus pentoxide, sulfur trioxide/pyridine complex, and chlorine. Reaction of alcohols with phosgene to give chloroformates which react with dimethyl sulfoxide to give alkoxysulfonium ions, followed by reaction with triethylamine, also effects oxidation. The reaction of the complexes of dimethyl sulfide and chlorine or N ‐chlorosuccinimide (NCS) with alcohols is proposed to give the same alkoxysulfonium complexes, which are efficiently converted into carbonyl products upon addition of triethylamine. Electrochemical activation of sulfides has also been successfully utilized. The activation of dimethyl sulfoxide is effected by many reagents, and these reactions as well as those involving activated sulfides evidently involve the alkoxysulfonium ion and the decisive oxidation step which occurs via the alkoxysulfonium ylide in all the reactions. Activation of dimethyl sulfoxide by oxalyl chloride, has become the most used of these oxidation procedures, but several of the other methods are also convenient and efficient.

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