Non-Pyrolytic Syntheses of Buckybowls: Corannulene, Cyclopentacorannulene, and a Semibuckminsterfullerene
作者:Andrzej Sygula、Peter W. Rabideau
DOI:10.1021/ja991169j
日期:1999.9.1
Corannulene (1), cyclopentacorannulene (2), and a C30H12 semibuckminsterfullerene (3) have been prepared by non-pyrolytic methods employing bromomethyl/dibromomethyl and/or dibromomethyl/dibromomethyl coupling with low-valent titanium or vanadium. Reductive coupling of tetrakis(dibromomethyl)fluoranthene (8) with vanadium(III) chloride and lithium aluminum hydride affords corannulene in 70−75% yield
Reduction of Bowl-Shaped Hydrocarbons: Dianions and Tetraanions of Annelated Corannulenes
作者:Ivan Aprahamian、Dorin V. Preda、Mihail Bancu、Anthony P. Belanger、Tuvia Sheradsky、Lawrence T. Scott、Mordecai Rabinovitz
DOI:10.1021/jo051949c
日期:2006.1.1
with lithium, the exception being systems that can stabilize the tetraanion with lithium by special means, such as aggregation or dimerization. One such system is cyclopenta[bc]corannulene (acecorannulylene), which gives a coordinativedimer that consists of two cyclopentacorannulene tetraanions, bound together in a convex−convex fashion by lithium cations. The points of contact in this dimer are two
使用锂和钾金属还原了几种退火的邻苯二环戊二烯衍生物。研究发现,去核作用通过改变电荷分布而影响香兰素的环戊烯特性。与六元环退火的衍生物的二价阴离子比corannulene二价阴离子具有更少的年环特性和更少的顺性。这种作用在周围的Corannulenes中更加明显。-与五元环退火。还原过程中使用的碱金属对结果有很大影响,特别是对还原度有很大影响。大多数衍生物仅通过钾而不是锂被还原为四阴离子,例外的是可以通过特殊方式(例如聚集或二聚)稳定四价阴离子的体系。一个这样的系统是环戊四烯[ bc ] corannulene(acecorannulylene),它给出一个配位二聚体,该二聚体由两个环戊四烯环戊四阴离子通过锂阳离子以凸-凸的方式结合在一起。在该二聚体中的接触点是来自每个环戊四烯环烯单元的两个再杂化的碳,它们被两个锂阳离子桥接在一起。
"Locking" the bowl-shaped geometry of corannulene: cyclopentacorannulene
作者:Atteye H. Abdourazak、Andrzej Sygula、Peter W. Rabideau
DOI:10.1021/ja00060a073
日期:1993.4
The discovery that buckminsterfullerene, C[sub 60], is a stable molecule due to geodesic and electronic properties inherent in the truncated icosahedral cage structure has generated a renewed interest in hydrocarbons with curved surfaces. The carbonframework of corannulene, which can be considered to represent the polar cap of buckminsterfullerene, is surprisingly flexible. In spite of its substantial
Synthesis of Corannulene and Alkyl Derivatives of Corannulene
作者:T. Jon Seiders、Eric L. Elliott、Gunther H. Grube、Jay S. Siegel
DOI:10.1021/ja991310o
日期:1999.9.1
Synthesis of corannulene and alkyl corannulene derivatives has been accomplished using solution-phase chemistry. The key step in the synthesis is the coupling of benzylic bromides of 1,6,7,10-tetraalkylfluoranthene derivatives by low-valent titanium to construct the corannulene nucleus. The use of low-valent titanium represents a viable alternative to flash vacuumpyrolysis methods previously developed
Cyclopentacorannulene: π-Facial Stereoselective Deuterogenation and Determination of the Bowl-to-Bowl Inversion Barrier for a Constrained Buckybowl
作者:Andrzej Sygula、Atteye H. Abdourazak、Peter W. Rabideau
DOI:10.1021/ja9521987
日期:1996.1.1
Attachment of an ethane or ethylene unit to the rim of corannulene produced relatively rigid bowls of dihydrocyclopenta- and cyclopentacorannulene, respectively. In contrast to the parent corannulenes, their inversion barriers are too high to be determined by the NMR coalescence methods. Due to the significant curvature of cyclopentacorannulene, deuterogenation is pi-facial specific; both heterogeneous and homogeneous catalysis lead exclusively to exo-dideuteriocyclopentacorannulene 2a. Equilibration of the endo- and exo-isotopomers allowed the determination of Delta G(double dagger) at 27.61-27.67 kcal/mol over the temperature range 52.1-99.3 degrees C and the estimation of Delta H-double dagger (27.3 +/- 0.7 kcal/mol) and Delta S-double dagger (-1.1 +/- 0.2 eu) for the bowl-to-bowl inversion. The inversion barrier calculated at the HF/6-31G*//3-21G level (25.9 kcal/mol) compares well with the experimental result.