描述了通过H 2 SO 4-催化的酮酯1的环脱水合成不饱和酸3以及将其转化为内酯4的过程。另一方面,PPA诱导了酮酸9的环化,产生了八氢蒽衍生物10a和10b的立体异构混合物。所述hydrofluorene衍生物的四个可能的外消旋体5,6,7,和8已经通过化学和催化还原的合成3和4。立液体氨引起的内酯还原裂解4点继续进行65%保持35%反转在苄基C-4a中不对称中心,得到的结构的反式与顺式酸5和8分别的同时催化氢解4点继续进行倒置产生顺式酸8。的锂液氨还原3给出反式酸6和CIS 7分别在23%和53%的收率,而催化加氢3次,得到81%的顺式酸8和13%的顺式酸7。甲酯的一些构象的性质17,18,19,和20已经从化学和NMR光谱数据推导出。
Synthetic studies towards complex diterpenoids. Part 11. Stereochemically defined synthesis of the racemates of 1,2,3,4,4a,9a-hexahydro-7-methoxy-1-methylfluorene-1-carboxylic acid
Two simple synthetic routes to 1,2,3,4-tetrahydro-7-methoxy-1 -methylfluorene-1 -carboxylic acid (1b), a potential intermediate towards gibberellins, and its stereochemicallydefined transformations to three racemates of 1,2,3,4,4a,9a- hexahydro-7-methoxy-1 -methylfluorene-1 -carboxylic acid (4b)–(6b) are described. Catalytic hydrogenation of (1 b) yields a mixture of (5b) and (6b) in a ratio of ca