PROCESS FOR THE PREPARATION OF CALCIPOTRIOL

摘要

Process comprising the step of reacting a C-22 phenylsulphonyl derivative of cholecalciferol of Formula (2), wherein R1 and R2 are the same or different and represent hydroxyl protecting groups, with a silyl derivative of alfa-hydroxy aldehyde of Formula (3), wherein R3 represents silyl group of formula Si(R4) (R5)(R6), where R4-R6 are the same or different and represent C1-6 alkyl or phenyl groups, in the presence of a strong organic base in aprotic solvent, followed by a reductive desulfonation of the diastereomeric mixture of alfa- hydroxysulfones with sodium amalgam, removing the hydroxyl protecting groups, and purification, leads to calcipotriol containing less than 0,3% of (22Z)-isomer and free of mercury traces.