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|Title:||Vitamin B12 and BF3-etherate as catalysts in synthesis of some C4-C12-alkyl -D-xylopyranosides|
|Authors:||Petrović, Zorica D|
|IPC Code:||Int.Cl.7 C 07 C|
|Abstract:||Two methods are presented for synthesis of some C4-C12-alkyl -D-xylopyranosides. The first method is the vitamin B12-catalyzed reaction of glycosylation of acetobromoxylose with alkanols (ROH) (C4-C12). The reaction is carried out with 2 mol% of vitamin B12, with respect to xylosyl bromide, under argon at room temperature. Under these conditions peracetylated C4-C12-alkyl -D-xylopyranosides are obtained. Following chromatographic purification these products are de-esterified with a mixture of methanol-triethylamine-water (2:1:1) to give corresponding alkyl -D-xylopyranosides in 50-60% yield. In all cases 3,4-di-O-acetyl-D-xylal is obtained, as the product of reductive elimination of peracetylated xylosyl bromide (15-25%). The second method is synthesis of C4-C12-alkyl -D-xylopyranosides performed by glycosylation of corresponding alkanols with tetra-O-acetyl -D-xylopyranose in the presence of BF3-etherate, as a Lewis acid catalyst. This glycosylation proceeds in only moderate yield (45-55%), but simplicity of this method and avoidance of expensive heavy metal catalysts make such procedure attractive.|
|Appears in Collections:||IJC-B Vol.45B(01) [January 2006]|
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