- Synthesis of raffinose family oligosaccharides by regioselective de-O-benzylation with Co2(CO)8/Et3SiH/CO system
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A convenient approach for synthesis of raffinose, stachyose, and verbascose using sucrose as the starting material is presented. The key step is the regioselective de-O-benzylation with Co2(CO)8/Et 3SiH/CO system, followed by a high α-selective glycosylation. The newly developed de-O-benzylation system is efficient in removing the primary benzyl groups of sucrose and raffinose under mild condition and with high selectivity. Using thioglycoside as donor, NIS/AgOTf as promoter and DTBMP as additive, glycosylation of acid labile sucrose substrate is achieved in high yield.
- Zhao, Yue-Tao,Niu, Shan,Huang, Lu-Bai,Wang, Ji-Ming,Yin, Zhao-Jun,Li, Qing,Li, Zhong-Jun
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p. 5022 - 5028
(2013/06/27)
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- Isolation and Identification of Oligosaccharides Produced from Raffinose by Transgalactosylation Reaction of Thermostable α-Galactosidase from Pycnoporus cinnabarinus
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The thermostable α-galactosidase purified from Pycnoporus cinnabarinus catalyzed the galactosyltransfer reaction in the hydrolysis of raffinose and produced several kinds of transfer products.The main transfer products were isolated and the stuctures of the six kinds of transfer products (oligosaccharides A, B, C, D, E, and F) were investigated by acid and enzymatic hydrolysis, and methylation analysis.Oligosaccharides A, B, C, D, E, and F were identified as O-α-D-galactopyranosyl-(1->3)-O-α-D-glucopyranosyl-(1->2)-β-D-fructofuranoside, O-α-D-galactopyranosyl-(1->3)-O-α-D-galactopyranosyl-(1->6)-O-α-D-glucopyranosyl-(1->2)-β-D- fructofuranoside, stachyose, O-α-D-galactopyranosyl-(1->3)-O-α-D-galactopyranosyl-(1->6)-O-α-D-galactopyranosyl-(1->6)-O-α-D-glucopyranosyl-(1->2)-β-D-fructofuranoside, verbascose, and ajugose, respectively.
- Mitsutomi, Masaru,Ohtakara, Akira
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p. 2305 - 2312
(2007/10/02)
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