An efficient route to vitaminD3 analogues functionalized at C-11 is described. Key features of this synthesis are: (i) the development of a novel and efficient route for the introduction of the 25-hydroxylated side chain, present in the most important metabolites of vitaminD3, and (ii) the stereoselective functionalization of the C-ring of 1α,25-(OH)2-D3 at C-11.
This work describes our studies on the functionalization at C11 of CD-ring fragments of vitamin D-3 using organocopper reagents. As an application, an efficient, convergent synthesis of 11 alpha-[3,3-(dimethoxy)propyl] calcitriol analogue 2, which may be useful for the construction of affinity columns for the purification of 1 alpha,25-(OH)(2)-vitamin D-3 receptors, is described. (C) 1997 Elsevier Science Ltd.