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.
Preparation of<i>C</i><sub>3</sub>-Symmetric Homochiral<i>syn</i>-Trisnorbornabenzenes through Regioselective Cyclotrimerization of Enantiopure Iodonorbornenes
作者:A. F. G. Masud Reza、Shuhei Higashibayashi、Hidehiro Sakurai
DOI:10.1002/asia.200900132
日期:2009.8.3
mixtures. The efficient preparation of (−)‐syn‐1 was established in short steps, including the newly developed cyclotrimerization reaction. The thus‐prepared homochiral (−)‐syn‐1 can serve as a keyintermediate for the synthesis of C3‐symmetric homochiral cup‐shaped molecules with a helical arrangement of substituents. Introduction of several types of substituents was well demonstrated through palladium‐catalyzed
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。
Trimethylsumanene: Enantioselective Synthesis, Substituent Effect on Bowl Structure, Inversion Energy, and Electron Conductivity
C3 symmetric chiral trimethylsumanene was enantioselectively synthesized through Pd-catalyzed syn-selective cyclotrimerization of an enantiomerically pure iodonorbornenone, ring-opening/closing olefin metathesis, and oxidative aromatization where the sp3 stereogenic center was transmitted to the bowl chirality. Chiral HPLC analysis/resolution of the derivatives were also achieved. Based on theoretical calculations, the columnar crystal packing structure of sumanene and trimethylsumanene was interpreted as due to attractive electrostatic or CH–π interaction. According to the experimental and theoretical studies, the bowl depth and inversion energy were found to increase on methylation for sumanene in contrast to corannulene. Dissimilarities of the effect of methylation on the bowl structure and inversion energy of sumanene and corannulene were ascribed to differences in steric repulsion. A double-well potential model was fitted to the bowl structure–inversion energy correlation of substituted sumanenes, with a small deviation. The effects of various substituents on the sumanene structure and bowl-inversion energy were analyzed by density functional theory calculations, and it was shown that the bowl rigidity is controlled by a combination of electronic and steric effects of the substituents. The electron conductivity of trimethylsumanene was investigated by time-resolved microwave conductivity method, compared with that of sumanene.