[4+2] Cycloadditions of 2-(trialkylsilyloxy)-allylidenecyclopropanes - synthesis of spiro[2.5]octan-5-ones
作者:Thies Thiemann、Stephan Kohlstruk、Gerhard Schwär、Armin de Meijere
DOI:10.1016/0040-4039(91)80812-k
日期:1991.7
readily react with a variety of dienophiles at temperatures ranging from 0 to 130°C to give derivatives 5–10 of 5-(trialkylsilyloxy)spiro-[2.5]oct-4-ene or the corresponding hydrolysis products 10, 12. Weak dienophiles like cyclohexenone and cyclopentenone give spiro[2.5]octan-5-one derivatives only under BF3 catalysis and with poor yields.
以前未知的2-(三烷基甲硅烷氧基)亚烷基环丙烷2a-d是通过容易获得的环丙基亚烷基链烷酮1-R 1的甲硅烷基化制备的,产率很高。二烯图2a-d容易地与在温度范围从0至130℃的各种亲双烯体的反应,得到衍生物5-10的5-(三烷基甲硅烷)螺- [2.5]辛-4-烯或相应的水解产物10,12。如环己烯酮和环戊烯酮之类的弱亲二烯物仅在BF 3催化下才能得到螺[2.5] octan-5-one衍生物,收率很低。