A Strain Induced Change of Mechanism from a [2+2+2] to a [2+1+2+1] Cycloaddition Reaction

作者：Anne Florence Tran Van; Goetz Silas; Neuburger Markus; Wegner Hermann A^*

来源：Organic Letters, 2014, 16(9): 2410-2413.

DOI：10.1021/ol5007604

While investigating the [2 + 2 + 2] cycloaddition as a tool to build up strained oligophenyl systems with a diyne-ethylene glycol macrocyle, a surprising change of mechanism was observed. Instead of the expected [2 + 2 + 2] para-terphenyl, the ortho-terphenyl product explained by a formal [2 + 1 + 2 + 1] cycloaddition was formed. An eta(4)-coordinated metal-cyclobutadiene is proposed as the key structure in the catalytic cycle, which is formed to release the induced strain. The optical properties of the ortho-terphenyl products have been measured as well as the coordination ability of Na+ and K+.

• 出版日期2014-5-2