25(S),26-Dihydroxyvitamin D3

2-{(3S,8S,9S,10R,13R,14S,17R)-10,13-Dimethyl-17-[(R)-1-methyl-4-((S)-2,2,4-trimethyl-[1,3]dioxolan-4-yl)-butyl]-2,3,4,7,8,9,10,11,12,13,14,15,16,17-tetradecahydro-1H-cyclopenta[a]phenanthren-3-yloxy}-tetrahydro-pyran