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 development.

Synthesis, structure, and biological activity of des-side chain analogues of 1α,25-dihydroxyvitamin†D3 with substituents at C18.

An improved synthetic route to 1α,25-dihydroxyvitamin D(3) des-side chain analogues 2 a and 2 b with substituents at C18 is reported, along with their biological activity. These analogues display significant antiproliferative effects toward MCF-7 breast cancer cells and prodifferentiation activity toward SW480-ADH colon cancer cells; they are also characterized by a greatly decreased calcemic profile. The crystal structure of the human vitamin D receptor (hVDR) complexed to one of these analogues, 20(17→18)-abeo-1α,25-dihydroxy-22-homo-21-norvitamin D(3) (2 a) reveals that the side chain introduced at position C18 adopts the same orientation in the ligand binding pocket as the side chain of 1α,25-dihydroxyvitamin D(3).

Design and synthesis of active vitamin D analogs.

A review of the design and synthesis of structural analogs of the vitamin D hormone recently investigated in our laboratories, and the first report on a new class of vitamin D analogs characterized by an aromatic D-ring, is described.