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2005
Carbohydrates
U 0500
Synthesis of Novel Anellated Pyranosides as Precursors of C-Nucleoside Analogues Using Isopropyl 6-O-Acetyl-3-deoxy-4-S-ethyl-4-thio-α-D-threo-hexopyra33- 237 nosid-2-ulose.
— The push—pull activated branched-chain sugar (IV) reacts with hydrazine or methylhydrazine (V) to the corresponding pyrazolo anellated pyranosides,
e.g. (VI). Due to the relative high stability of its push—pull system and also to the steric
hindrance of the methylthio groups, (IV) does not react with other nucleophiles under
several reaction conditions. Displacement of one of the methylthio groups by using
hydrodesulfurization gives rise to formation of a compound having increased electrophilic reactivity, cf. (VII). Thus, reaction of (VII) with hydrazines, e.g. (IX), benzamidine salt (XI) and hydroxylamine yields the pyrazolo, cf. (VIII) and (X), pyrimido
(XII), and isoxazolo (XIII) anellated pyranosides. Ulose (VII) reacts with secondary
amines under substitution of the methylthio group affording the corresponding aminomethylene uloses. — (RUIZ, R. M.; MARTINEZ, I. O.; MICHALIK, M.; REINKE,
H.; SUAREZ, J. Q.; PESEKE*, K.; J. Carbohydr. Chem. 23 (2004) 5, 337-351;
Fachber. Chem., Univ. Rostock, D-18051 Rostock, Germany; Eng.) —
H. Hoennerscheid
2005
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