Syntheses of Novel Belt-Type Molecules Using Dewar Benzenes.

我们通过引入1,4-缩醛桥接杜瓦苯作为构建块，成功地合成并表征了新型的对苯基应变大环。目前的结果表明，杜瓦苯单元可以作为一个屏蔽的对苯单元来构造应变大环体系。通过使用其他间隔剂和/或连接方式，基于目前的构建块方法，可以获得具有独特结构和性能的多种含对苯乙烯的应变大环。我们还成功地开发了一种新的双二烯分子，在与活化的亲二烯试剂连续两次Diels-Alder反应后产生杜瓦苯骨架。1:2加合物的脱氢得到了相应的杜瓦形式的多烯。基于合成方案，还可以得到具有其他1,4-桥接单元的类似双二烯体系。因此，目前的结果为杜瓦衍生物开辟了一条独特而通用的途径，而杜瓦衍生物又将被视为新型环烷和带型分子的潜在前体。

We have successfully synthesized and characterized novel p-phenylene-based strained macrocycles by introducing 1,4-acetal-bridged Dewar benzene as a building block. The present results demonstrate that a Dewar benzene unit can be exploited as a masked p-phenylene unit for the constraction of strained macrocyclic systems. By using other spacers and/or connection modes, a variety of p-phenylene-containing strained macrocycles with unique structures and properties may well become available based on the present building block aproach.We have also successfully developed a new bisdiene molecule that produces a Dewar benzene skeleton upon two successive Diels-Alder reactions with activated dienophiles. Dehydrogenation of the 1: 2 adducts provides the corresponding Dewar form of polyacenes. Similar bisdiene systems possessing other 1,4-bridging units may also be available based on the synthetic scheme. Therefore, the present results open a unique and versatile route to Dewar derivatives which, in turn, would be regarded as potential precursors for novel cyclophanes as well as belt-type molecules.