Synthesis of [n]- and [n.n]Cyclophanes by Using Suzuki−Miyaura Coupling
摘要:
Reaction of the bis-9-BBN adduct of several dienes with 1,3-dibromobenzene via Suzuki coupling leads to a series of [n]metacyclophanes ranging in size from 10 to 17 atom members. In each case, two carbon-carbon bonds are formed in one reaction vessel. However, when the bis-9-BBN adduct of 1,5-hexadiene is coupled with a variety of aryl dihalides, larger [n.n]cyclophanes were formed in preference to the [n]cyclophanes. Four carbon-carbon bonds are formed in this instance. Single-crystal X-ray analyses of these [n.n]cyclophanes reveal interestingly shaped molecules with large cavities.
该手稿描述了一种在温和条件下通过环氧化物的开环聚合(ROP)合成聚醚具有前所未有的反应性的双功能有机催化剂。该双功能催化剂在两个末端结合了两个9-borabicyclo [3.3.1]壬烷中心,作为路易斯酸性位点以进行环氧化物活化,并在中间将卤化季铵作为起始位点。该催化剂可以很容易地分两步从市售存货中以高达公斤级的产率(约100%)制备。有机硼催化剂介导的环氧化物的ROP表现出低催化剂负载(5 ppm)的活性,并且能够合成分子量超过一百万克每摩尔(> 10 6 g摩尔-1)的聚醚)。基于对催化剂晶体结构,MALDI-TOF和11 B NMR光谱学的研究,提出了分子内铵阳离子辅助S N 2机理,并通过DFT计算进行了验证。