An expeditious route to 1α,25-dihydroxyvitamin D3 and its analogues by an aqueous tandem palladium-catalyzed a-ring closure and suzuki coupling to the C/D unit

Abstract

Chemical equation presented Daily vitamins: A mild, general, and highly stereoselective Pd0-catalyzed cascade to the triene system of the hoi mone 1α,25-dihydroxyvitamin D3 and six representative analogues is reported. The intramolecular cyclization of an enol-triflate (lower fragment) followed in situ by Suzuki Miyaura coupling with an alkenyl boronic ester (upper fragment, also efficiently prepared by Pd0-catalyzed coupling) in equimolar amounts under protic conditions is ideal for the preparation of small amounts of new vitamin D analogues for biological testing (see scheme). © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.