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Phase-transfer-catalyzed synthesis of a phenylseleno α-ketoside of N-acetylneuraminic acid, (phenyl 5-acetamido-3,5-dideoxy-d-glycero-α-d-galacto-2-selenononulopyranosid)-onic acid; a new sialidase inhibitor

✍ Scribed by Jörg Rothermel; Hans Faillard

Publisher: Elsevier Science
Year: 1990
Tongue: English
Weight: 295 KB
Volume: 208
Category: Article
ISSN: 0008-6215
DOI: 10.1016/0008-6215(90)80105-c

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✦ Synopsis

Selenium-substituted carbohydrates are known but rare compounds'. In sialic acid chemistry, they are gaining an increasing interest with regard to their use in stereocontrolled glycosidation reactions.

Ito and Ogawaz4 reported a phenylselenosubstituted sialic acid derivative which they used in glycosidation reactions.

They introduced a phenylseleno group at C-3 of sialic acid via the 2,3-dehydrosialic acid derivative. This group at C-3 was used as a stereocontrolling auxiliary for preparing a-ketosides of N-acetylneuraminic acid (1). Also other authors5*6 reported glycosidation reactions with various selenium-substituted carbohydrates. However, up to now, no aryl or alkyl selenoketosides of sialic acids have been described.

We report herein the synthesis of a phenyl a-selenoketoside of N-acetylneuraminic acid (1). Because of the instability of free benzeneselenol, a special method of glycosidation was required. We succeeded in preparing the appropriate ketoside by use of phase-transfer catalysis, which we have already described as a very effective method for preparing aryl' a-ketosides and arylthio a-ketosides' of N-acetylneuraminic acid.

The reaction of 3 with benzeneselenol in the two-phase system, chloroform-O&r aqueous sodium hydroxide, resulted in the peracetylated phenyl selenoglycoside 4 with high stereoselectivity, good yield, and in a very short reaction time. Whereas free selenophenol is very unstable, the ketoside 4 is a stable compound at room temperature. It crystallized easily from ethyl acetate-petrol ether. The a-D configuration of the

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