Methylation of carbohydrates bearing base-labile substituents, with diazomethane-boron triflouride etherate. I

Various tetra-O-acetyl-D-hexopyranoses were known to undergo acetyl migration upon methylation with Purdie's reagents; thus, 1,2,3,4-tetra-O-acetyl-β-D-glucopyranose, 1,2,3,6-tetra-O-acetyl-β-D-glucopyranose, and 1,3,4,6-tetra-O-acetyl-β-D-glucopyranose and its α anomer are converted into methy...

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Detalles Bibliográficos
Autores principales: Mastronardi, I.O., Flematti, S.M., Deferrari, J.O., Gros, E.G.
Formato: JOUR
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_00086215_v3_n2_p177_Mastronardi
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Sumario:Various tetra-O-acetyl-D-hexopyranoses were known to undergo acetyl migration upon methylation with Purdie's reagents; thus, 1,2,3,4-tetra-O-acetyl-β-D-glucopyranose, 1,2,3,6-tetra-O-acetyl-β-D-glucopyranose, and 1,3,4,6-tetra-O-acetyl-β-D-glucopyranose and its α anomer are converted into methyl 2,3,4,6-tetra-O-acetyl-β-D-glucopyranoside when methylated with methyl iodide and silver oxide. It is now found that, when each of the above compounds is treated with diazomethane-boron trifluoride etherate, the methylated product is produced in high yield, with the methyl ether group in the expected position. Under the same conditions, 1,3,4,6-tetra-O-α-D-galactopyranose is converted into the 2-methyl ether without the acetyl migration which had been observed when the tetra-O-acetyl-D-galactopyranose was methylated with Purdie's reagents. The tetra-O-acetyl-O-methyl-D-hexopyranoses were then transformed by deacetylation into the following mono-O-methylhexoses: 2-O-methyl-β-D-glucose, 4-O-methyl-D-glucose, 6-O-methyl-α-D-glucose, and 2-O-methyl-β-D-galactose. © 1966.