Adjusting the Features of Active Metallocene Ziegler Systems fot Their Potential Use as Carbon–Carbon Coupling Catalysts in Organic Synthesis
作者:Sven Thiele、Gerhard Erker
DOI:10.1002/cber.19971300210
日期:1997.2
A variety of bent metallocene dichloride/methylalumoxane catalysts, derived from the zirconocene complexes 10, 12-18, have been employed in intramolecular olefin-coupling reactions yielding monomeric or dimeric products. This was achieved by using optimized reaction conditions employing low substrate concentrations (1.0-1.8 M) and rather long reaction times. Under these particular conditions, 1,5-hexadiene
多种弯曲的金属茂二氯化/甲基铝氧烷的催化剂,由二茂锆络合物衍生10,12-18,都在分子内烯烃的偶联反应,产生单体或二聚体的产品已采用。这是通过使用优化的反应条件实现的,该条件采用低底物浓度(1.0-1.8 M)和较长的反应时间。在这些特定条件下,将1,5-己二烯环二聚,得到1-亚甲基-3-(环戊基甲基)环戊烷(11)。1,6-庚二烯干净地转化为亚甲基环己烷,顺式-1,2-二乙烯基环戊烷(19)和顺式-1,2-二乙烯基环己烷(22))被环化以分别产生2-亚甲基双环[3.3.0]辛烷(20)和7-亚甲基双环[4.3.0]壬烷(23)。在许多情况下,环化产物伴随有源自双键变换反应的异构体,这些异构体通常在选择的特定反应条件下在这些催化剂体系中迅速发生,以使产物保持单体状态。