Nor-1α, 25-dihydroxy-22-oxo-vitamin D3 4 was synthesized by the coupling of known compound 5 and the A-ring phosphine oxide 6 followed by deprotection of the hydroxy functions. Nor-1α, 25-dihydroxy-22-oxo-vitamin D3 4 was synthesized by the coupling of known compound 5 and the A-ring phosphine oxide 6 followed by deprotection of the hydroxy functions.