Herein, we describe our studies on the synthesis of 1α,25-dihydroxyvitamin D 3 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 development.