SYNTHESIS OF PHOSPHORIC-ACID DIESTERS OF 7-BETA-HYDROXYCHOLESTEROL AND OF CARBOHYDRATES

In order to enhance the antitumor efficacy of 7 beta-hydroxycholestero l by targetting its action to defined organs, the phosphoric acid este rs of 3(7 beta-hydroxycholesteryl) and of 6(galactopyranosyl) I or 6(m annopyranosyl) 2 were synthesized by the phosphoramidite method (with protected C-1, 2, 3, 4 hydroxyl groups for the carbohydrates). As the protection of the sugars increased the length of the synthesis, we dec ided to use the hydrogen-phosphonate methodology which leads to a sele ctive phosphorylation at the primary alcohol of carbohydrates and avoi ds the use of protected carbohydrates. Compound 2 was synthesized in g ood yield. However compound 1, probably due to steric hindrance, could not be obtained by this second method.