SYNTHESIS

摘要

The present invention provides an improved synthesis of a class of steroid saponins. Furthermore, the present invention provides a method of selectively discriminating between the C2 and C3 hydroxyl groups of a mono-glycosylated steroid saponin—a key step in the preparation of this class of compounds. Additionally, the present invention provides a range of steroid saponin derivatives, and methods of making them.

主权项

1. A method for the preparation of a compound of Formula X wherein R1 is a sapogenin; R2, R3, and R4 are each independently an oxygen protecting group; R5 is an acyl group; R6 and R7 are H; R9 is selected from the group consisting of H, CH3, and an oxygen protected by an oxygen protecting group;the method comprising(i) reacting a compound of Formula A with an acylating agent in an acylation reaction in the presence of a base; wherein R1 is a sapogenin; R6 and R7 are each independently an oxygen protecting group; or when taken together form a cyclic di-oxygen protecting group; to provide a compound of Formula B R1 is sapogenin; R5 is an acyl group; R6 and R7 are each independently an oxygen protecting group or when taken together form a cyclic di-oxygen protecting group;(ii) reacting a compound of Formula B with a compound of Formula C under coupling conditions wherein R2, R3, and R4 are each independently an oxygen protecting group; R8 is a leaving group; and R9 is selected from the group consisting of H, CH3, and an oxygen protected by an oxygen protecting group;(iii) selectively removing the oxygen protecting groups at R6 and R7 to provide a compound of Formula X.