Design and synthesis of novel 1,25-dihydroxyvitamin D3 analogues having a spiro-oxetane fused at the C2 position in the A-ring

Four structurally novel stereoisomeric analogues of 1,25-dihydroxyvitamin D3 (3a-d) bearing a spiro-oxetane fused at the C2 position of the A-ring have been designed and synthesised.