Synthesis of conandroside: A dihydroxyphenylethyl glycoside from Conandronramaidioides

The key intermediate 2-(3,4-di-O-benzylphenyl)ethyl 2,6-di-O-acetyl-4-O-[(E ,Z) -3,4-di-O-benzylcaffeoyl)-beta-D-glucopy-ranoside (3) was xylosylated w ith peracetylated xylosyl trichloroacetimidate donor 4 to afford conandrosi de derivative 5. Deacetylation of compound 5 with a methanol solution of me thylamine resulted in the formation of compound 6, the monoacetyl derivativ e 6a and the caffeoyl-migrated derivative 6b in yields of 54%, 19% and 15%, respectively. Compound 6 was then debenzylated with 1,4-cyclohexadiene/pal ladium-carbon to afford conandroside (1), which was treated with dimethyl s ulfate in the presence of potassium carbonate to produce the methylated con androside 2. This compound was found to be identical to the reported "conan droside tetra-O-methyl ether" obtained by methylation of the extract from C onandron ramoidioides.