Synthesis and biological activity of 22-oxa CD-ring modified analogues of 1α,25-dihydroxyvitamin D3: cis-perhydrindane CE-ring analogues

The synthesis and biological activity of novel CD-ring modified analogues of 22-oxa-1α,25-dihydroxyvitamin D3, lacking the D-ring and featuring a connection between C-12 and C-21 (cis-perhydrindane CE-ring analogues), is described. The synthesis of the CE-ring system follows Meyersʹ methodology for the preparation of enantiomerically pure hydrinden-2-ones. The analogues show a complete lack of binding affinity for the vitamin D receptor (pig nVDR) and of antiproliferative activity (MCF-7 cells), as compared to calcitriol.