An Expeditious Route to 1a,25-Dihydroxyvitamin D3 and Its Analogues by an Aqueous Tandem Palladium-Catalyzed A-Ring Closure and Suzuki Coupling to the C/D Unit

PRANJAL GOGOI, RITA SIGUEIRO, SILVINA EDUARDO, AND ANTONIO MOURIÑO

CHEMISTRY-A EUROPEAN JOURNAL

WILEY-V C H VERLAG GMBH

Año: 2010 vol. 16 p. 1432 - 1435

0947-6539

Daily vitamins: A mild, general, and highly stereoselective Pd0-catalyzed cascade to the triene system of the hormone 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).