Synthesis and evaluation of A-Ring diastereomers of 1α,25-dihydroxy-22-oxavitamin D 3 (OCT) 1

Abstract A-ring diastereomers of 1α,25-dihydroxy-22-oxavitamin D 3 (OCT) ( 2 ), 3-epi-1α,25-dihydroxy-22-oxavitamin D 3 (3-epiOCT) ( 3 ) and 1,3-diepi-1α,25-dihydroxy-22-oxavitamin D 3 (1,3-diepiOCT) ( 4 ) were synthesized by the convergent method. In vitro binding affinity for rat vitamin D binding protein and calf-thymus vitamin D receptor, differentiation-inducing activity on HL-60 cells, and transcriptional activity of 3-epiOCT ( 3 ) and 1,3-diepiOCT ( 4 ) were evaluated in comparison with OCT ( 2 ), 1-epi-1α,25-dihydroxy-22-oxavitamin D 3 (1-epiOCT) ( 5 ) and 1α,25-dihydroxyvitamin D 3 ( 1 ).