PALLADIUM CATALYZED ALKYLATIVE CYCLIZATION USEFUL IN SYNTHESIS OF VITAMIN D AND ANALOGUES

摘要

The invention relates to a cycloaddition process for alkylation is particularly suitable for the synthesis of several vitamin D analogues in different side chains. Thus, a preferred synthesis relates to vitamin D analogues having a side chain R1, a first substantially pure precursor from a geometric point of view, having the structure (I) and one second precursor being used, the second precursor being 1, 7 enyne. These precursors are reacted in the presence of a palladium catalyst to form compounds having structure (II), R2 represents hydrogen, hydroxyl, lower alkoxy, fluorine or a protecting group, and R3 represents hydrogen, hydroxyl, lower alkoxy, fluorine or a protecting group.