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Regioselectivity in glycosylation reactions of 3,4-diols of α- and β-methyl glycosides derived from N-DMM-d-glucosamine
| Content Provider | Semantic Scholar |
|---|---|
| Author | Bohn, María L. Colombo, María Isabel Stortz, Carlos A. Rúveda, Edmundo A. |
| Copyright Year | 2007 |
| Abstract | Introduction There are many examples in the literature of selective glycosylations at the 4-position of 3,4diols derived from N-protected glucosamine, leaving a free 3-OH for a second glycosylation. In 1998, Magnusson and Ellervik reported reactions of selective galactosylation of 3,4-diols derived from N-protected glucosamine. Based on these experiments, they developed the synthesis of Le trisaccharide and SLe tetrasaccharide through a sequential double glycosylation (Ellervik and Magnusson, 1998). More recently, a number of publications reported that 4-OH of acceptors derived from β-Dglucosamine with different protecting groups at N-2 and O-6 was preferently, and in some cases exclusively, glycosylated under a variety of conditions (Figueroa-Perez and Verez-Bencomo, 1998; Cao et al., 1999; Gan et al., 1999; Zhang et al., 1999; Xia et al., 2000, 2002, 2003; Ercegovic et al., 2001; Gu et al., 2002; Yang et al., 2003; Xue et al., 2004; Gourmala et al., 2005; Tanaka et al., 2005). Taking into account these results, there are no simple reasons to explain this regioselection. However, recently it was proposed, at least for acceptor 1, the "stereo hindrance" effect of the N-Phth group (Fig. 1) to explain the exclusive 4-OH glycosylation (Gourmala et al., 2005). |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.idecefyn.com.ar/mmcv12/13.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
