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

摘要

An alkylative cycloaddition method is provided that is particularly useful for the synthesis of many of the Vitamin D analogues with differing side chains. Thus, a preferred synthesis is of Vitamin D analogues having a side chain R1 where a first precursor having the structure (a), with X being a halide or a pseudo halide, and a second precursor are provided, the second precursor being a 1,7 enyne. These precursors are reacted in the presence of a palladium catalyst to form compounds having structure (1), where R2 is hydrogen, hydroxyl, lower alkoxy, fluorine, or a protecting group, and R3 is hydrogen, hydroxyl, lower alkoxy, fluorine, or a protecting group.