A Formal Synthesis of Betamethasone. Issue 6 (2nd June 2015) - Wang, Shasha
Abstract: A formal synthesis of betamethasone from 5 α ‐pregnane‐3 β, 16 β, 20 S ‐triol is described. Key transformations are a bromination‐acetylation of triol, an SN 2 reaction of the resulting C16 α ‐bromide with dimethylcopperlithium to get the required C16 β ‐methyl group, and a double hydroxylation to prepare the dihydroxyacetone side chain. Abstract : A formal synthesis of betamethasone from pregnane‐3 β, 16 β, 20 S ‐triol is described. Key transformations are a bromination‐acetylation of triol, an SN 2 reaction of the resulting C16 α ‐bromide with dimethylcopperlithium to get the required C16 β ‐methyl group, and a double hydroxylation to prepare the dihydroxyacetone side chain.