| Popis: |
Glycosidation of the myo-inositol derivatives 2 and 3 by the diazirine 1 yields 90% of a diastereoisomer pair of β-D-glycosides in a 1:1 ratio, i.e.5/6 and 7/8, respectively (Scheme 1). The crystal structure of 3 shows a strong intramolecular H-bond, which persists in solution, as indicated by FT-IR and 1H-NMR spectra. Yields and diastereoselectivity are lower for the glycosidation of 24 by 1 (Scheme 3). The resulting 1,2- and 1,4-linked disaccharides 25–28 were isolated as their acetates 29–32. The previously determined crystal structure of 24 shows no intramolecular H-bonds. The yield of the glycosidation of 24, but not of 3, depends upon the concentration, indicating that activation of 24 by intermolecular H-bonds is required. Glycosidation of 2 and 3 with the trichloroacetimidate 14 gave mixtures of four (5,6,15, and 16), and six (7,8, and 17–20) disaccharides, respectively (Scheme 2). |
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