Industrial synthesis of maxacalcitol, the antihyperparathyroidism and antipsoriatic vitamin D3 analogue exhibiting low calcemic activity
Maxacalcitol, the 22-oxa-derivative of 1α,25-dihydroxyvitamin D 3 and used currently as an antihyperparathyroidism and antipsoriatic drug, has been synthesized in seven chemical steps from 1α- hydroxydehydroepiandrosterone on the basis of our previously developed route. The present synthesis allows the production of the protected form of the penultimate intermediate in 26% overall yield in a kilogram scale reaction employing neither difficult reaction conditions nor chromatographic purification, having overcome all the difficulties involved in the previous route.