Studies on the Synthesis of Vitamin D Analogs with Aromatic D-Ring

Herein, we describe our studies on the synthesis of 1α,25-dihydroxyvitamin D3 analogs possessing a benzene ring replacing the natural 5-membered D-ring by the Wittig-Horner and dienyne approaches. A key feature is the synthesis of a Cr(CO)3-complexed previtamin D derivative that enables the construction of vitamin D analogs with aromatic D-ring through a thermal [1,7]-H sigmatropic shift. This study establishes the basis for the design of new vitamin D analogs containing aromatic D-ring, complexed or uncomplexed to Cr(CO)3 type moieties for specific molecular recognition and drug research and developmentWe thank Xunta de Galicia (project GPC2014/001) and for financial support. Silvina Eduardo thanks the Spanish MEC for a fellowship. Rita Sigüeiro thanks Xunta de Galicia for a post-doctoral fellowship (Axudas posdoutorais, plan I2C, mod B)S