摘要:
                                Two novel stereoisomeric analogues of 1,25-dihydroxyvitamin D-3 bearing a spiro-oxetane at the C3 position of the A-ring have been designed and synthesized in a convergent manner. The absolute configuration at the Cl position of the synthesized compounds was determined by the circular dichroism exciton chirality method using the corresponding C1-allylic benzoates. The replacement of the C3-hydroxy group with a spiro-oxetane provided an advantageous conformational preference for the parent seco-steroids, which would facilitate the formation of a stable receptor complex. (C) 2014 Elsevier Ltd. All rights reserved.