(3S)-4-[(1R,3R,7E,17β)-1,3-bis{[tert-butyl(dimethyl)silyl]oxy}-2-methylidene-9,10-secoestra-5,7-dien-17-yl]-3-ethylpentan-1-ol 在
camphor-10-sulfonic acid 作用下,
以
甲醇 为溶剂,
反应 1.0h,
以69%的产率得到22S-ethyl-2-methylidene-19,25,26,27-tetranor-1α,24-dihydroxyvitamin D3