通过钯纳米团簇催化对映纯的碘化冰片的新的区域选择性环三聚,合成了具有刚性杯形结构的C 3-对称同手性(-)-顺式-trisoxonorborna苯1。环三聚的产率取决于钯簇的稳定性,其由反应混合物的外观和TEM图像确定。包括新开发的环三聚反应在内的短步伐就建立了(-)- syn - 1的高效制备方法。如此制备的同手性(-)- syn - 1可以用作合成C 3的关键中间体具有螺旋形取代基的对称对称手性杯状分子。通过钯催化的与(-)- syn - 1的相应磷酸酯和三氟甲磺酸酯的偶合钯偶联反应已很好地证明了几种取代基的引入。
Asymmetric Synthesis of a Chiral Buckybowl, Trimethylsumanene
作者:Shuhei Higashibayashi、Hidehiro Sakurai
DOI:10.1021/ja802822k
日期:2008.7.1
The first asymmetric synthesis of a chiral buckybowl, a C(3) symmetric (C)-8,13,18-trimethylsumanene (1), was achieved by employing a synthetic strategy that translates chirality at sp(3) centers into bowl chirality. The synthesis features a syn selective cyclotrimerization of an enantiopure halonorbornene derivative, tandem ring-opening/closing olefin metathesis reactions, and DDQ oxidation at low temperature. The bowl-to-bowl inversion energy of 1 was determined as 21.6 kcal/mol by circular dichroism spectra measurement.