John Sereno

Stereoselective total synthesis of 1α,25S,26-trihydroxycholecalciferol

A total synthesis of 1α,25S,26-trihydroxycholecalciferol (2) has been accomplished via an efficient convergent approach. The remote chiral center at C-25 was introduced by a regiospecific and diastereoselective 1,3-dipolar cycloaddition of the C-23 nitrone 27 with methyl methacrylate. Subsequent transformation of the resulting isoxazolidine led to the key synthon 3, which on coupling to the anion 4 and deprotection produced the metabolite 2.

Total synthesis of 1α,25,28-trihydroxyergocalciferol

Abstract A convergent total synthesis of 1α,25,28-trihydroxyergocalciferol (1), using an available A ring synthon and a CD synthon which was prepared via a thermodynamically controlled dipolar cycloaddition of methyl 3,3-dimethylacrylate and a C-23 nitrone followed by subsequent removal of the nitrogen function, is described.