The ortho-alkynylbenzoates are a new type of glycosyl donors (Fig. 1), which undergo glycolsylation in the presence of a catalytic amount of a gold(I) complex. The carbohydrates for glycolsylation can be D-glucopyranose, D-glucosaminepyranose, D-galactopyranose, L-rhamnopyranose, L-arabofuranose, D-ribofuranose, etc. Other carbohydrate ortho-alkynylbenzoate donors can also be prepared according to the carbohydrate chemists’ needs through the same synthetic method.
Depending on the type of carbohydrates and the preparative conditions as well, a varied α:β anomer ratios of the donors are attained. Experiments showed little difference between the pair of anomers in glycosylation in accord with the glycosylation mechanism; thus the anomeric mixtures need not to be separated but can be directly used in the glycosylation reactions. For details of the methodology, see the followed references.
Ref: 1. Biao Yu, etc. Angew. Chem. Int. Ed. 2011, 50, 4933 –4936.
2. Biao Yu, etc. Angew. Chem. Int. Ed. 2011, 50, 8329 –8332.
3. Biao Yu, etc. Chem. Commun., 2010, 46, 6060–6062.
4. Biao Yu, etc. Chem. Commun., 2011, 47, 7515–7517.
5. Biao Yu, etc. Chem. Eur. J. 2010, 16, 1871 – 1882.
6. Biao Yu, etc. J. Org. Chem. 2010, 75, 6879–6888.
7. Biao Yu, etc. Tetrahedron Letters. 49 (2008) 3604–3608.