作者:Nigel Broom、Peter J. O'Hanlon、Thomas J. Simpson、Rosamund Stephen、Christine L. Willis
DOI:10.1039/p19950003067
日期:——
to a directing effect from the lactone carbonyl at C-3 since osmylation of the analogous lactols 3, acetals 4 and cyclic ethers 5 gave attack mainly from the less hindered exo-face. The exo-acetonide 7 was prepared in a 3-stage procedure from cis-bicyclo[3.2.0]heptenone 6 in 54% yield. In this case the stereoselectivity of the osmylation reaction was governed, as expected, by the conformation of the
在各种条件下,用四氧化处理顺式-2-氧杂双环[3.3.0] oct-6-en-3-one 1,主要导致从更受阻的烯烃表面进攻,得到二元醇的保护。 ,内切丙酮化物8为主要产品。它由于从内酯羰基在C-3,因为类似的乳醇3的锇酸酯化一个引导效果是显而易见的是,该反应的立体化学结果是,缩醛4个环状醚得到5攻击主要从较少受阻外型面取向。以顺式三步法制得外-丙酮化物7-双环[3.2.0]庚酮6的产率为54%。在这种情况下,如预期的那样,通过双环骨架的构象控制了osmylation反应的立体选择性,没有明显的来自羰基酮的指导作用。