described starting from the known previtamin D3 adduct 6. The sequence involves the stereoselective allylic bromination to 9, followed by substitution with mercuric(II)acetate which occurs with retention of configuration to yield acetate 22. Basic hydrolysis gives diol 7, a known precursor of 1α-OH vitamin D3.
从已知的
维生素原D 3加合物6开始描述了
维生素D 3中1α-OH功能的高效立体选择引入。该序列包括将立体选择性的烯丙基
溴化至9,然后用
乙酸汞(II)取代,后者在保留构型的情况下发生,从而生成
乙酸22。碱性
水解得到已知的1α-OH
维生素D 3的前体二醇7。