作者:George Büchi、Ping-Sun Chu
DOI:10.1016/0040-4020(81)80018-x
日期:1981.1
Condensation of 1,2 - dimethylcyclopentene 10 with 2 - methyl - 4,4,5 - trimethoxycyclohexa - 2,5 - dienone 7 in methylene chloride - nitromethane with added stannic chloride gave a mixture of the two diastereomeric bicyclo[3.2.1]octanes 13 and 14 by ionic [4 + 2)cycloaddition. After selective reduction of the saturated carbonyl group with sodium borohydride, and hydrogenation of the double bond the
1,2-二甲基环戊烯10与2-甲基-4,4,5-三甲氧基环己-2,5-二烯酮7在二氯甲烷-硝基甲烷中的氯化缩合,得到氯化锡,得到两种非对映双环[3.2.1]辛烷的混合物通过离子[4 + 2)环加成反应得到13和14。用硼氢化钠选择性还原饱和羰基并氢化双键后,可通过色谱法分离两个差向异构体18和20(比率3.3:1)。羟基的保护在18与二氢吡喃和,减少α-methoxyketone的19与钙在液氨,得到酮21。然后通过维蒂希(Wittig)烯化,然后使羟基去保护,来制备裸草甾醇1。