Sumanene is a polycyclic aromatic hydrocarbon and of scientific interest because the molecule can be considered a fragment of buckminsterfullerene. Due to this connection and also its bowl shape, Sumanene is also known as a buckybowl. Suman means "flower" in both Hindi and Sanskrit.[ Towards the design of tricyclopenta def, triphenylene (sumanene): a bowl-shaped hydrocarbon featuring a structural motif present in C60 (buckminsterfullerene) Goverdhan Mehta, Shailesh R. Shah and K. Ravikumar Journal of the Chemical Society, Chemical Communications, 1993, (12), 1006 - 1008 ] The core of the arene is a benzene ring and the consists of alternating benzene rings (3) and cyclopentadiene rings (3). Unlike fullerene, sumanene has benzyl positions which are available for .
Organic synthesis
The structure of Sumanene can be inferred from oxidation of 1,5,9-trimethyl
triphenylene but the first practical synthesis starts from
norbornadiene.
[ A Synthesis of Sumanene, a Fullerene Fragment Hidehiro Sakurai, Taro Daiko, and Toshikazu Hirao Science, Vol 301, Issue 5641, 1878 , 26 September 2003 ] Norbornadiene is converted into a
stannane by action of
N-Butyllithium,
dibromoethane and tributyltinchloride. An
Ullmann reaction of this stannane with CuTC affords the benzene core. The methylene bridges () created in this conversion then migrate in a
tandem reaction ring-opening metathesis and ring-closing metathesis by the Grubbs' catalyst. The final structure is obtained by oxidation by DDQ.
Properties
Sumanene is a bowl-shaped
molecule with a bowl depth of 118
.
[ Structural Elucidation of Sumanene and Generation of Its Benzylic Anions Hidehiro Sakurai, Taro Daiko, Hiroyuki Sakane, Toru Amaya, and Toshikazu Hirao J. Am. Chem. Soc., 127 (33), 11580 -11581, 2005 ] The 6 hub carbon atoms are pyramidalized by 9° and the molecule displays considerable bond alternation (138.1 to 143.1 pm). Sumanene also experiences
bowl-to-bowl inversion with an inversion barrier of 19.6
kilocalorie/mol (82
kilojoule/mol) at 140 °C which is much higher than that found for its
corannulene cousin.
Like any benzylic
hydrogen atom, the sumanene protons can be abstracted by a strong base such as t-butyl lithium to form the sumanene mono
carbanion. This strong
nucleophile can react with an
electrophile such as trimethylsilyl chloride to the
trimethylsilyl derivative.
The trianion has also been reported.[Hidehiro Sakurai, Taro Daiko, Hiroyuki Sakane, Toru Amaya, and Toshikazu Hira; J. Am. Chem. Soc., 2005, 127 (33), pp 11580–11581 ] Electron transport properties have been investigated [ Anisotropic Electron Transport Properties in Sumanene Crystal Toru Amaya, Shu Seki, Toshiyuki Moriuchi, Kana Nakamoto, Takuto Nakata, Hiroyuki Sakane, Akinori Saeki, Seiichi Tagawa and Toshikazu Hirao J. Am. Chem. Soc., 2009, 131 (2), pp 408–409 ][ The electrochemical inspection of the redox activity of sumanene and its concave CpFe complex Piero Zanello, Serena Fedi, Fabrizia Fabrizi de Biani, Gianluca Giorgi, Toru Amaya, Hiroyuki Sakane and Toshikazu Hirao
Dalton Trans., 2009, 9192-9197 ] as well as carbon NMR[ Solid-state 13C NMR investigations of 4,7-dihydro-1H-tricyclopentadef,jkl,pqrtriphenylene (sumanene) and indeno1,2,3-cdfluoranthene: Buckminsterfullerene moieties Merrill D. Halling, Anita M. Orendt, Mark Strohmeier, Mark S. Solum, Vikki M. Tsefrikas, Toshikazu Hirao, Lawrence T. Scott, Ronald J. Pugmire and David M. Grant Phys. Chem. Chem. Phys., 2010, 12, 7934-7941 ]
Derivatives
Sumanene derivatives
[ Bowl-to-bowl inversion of sumanene derivatives Toru Amaya, Hiroyuki Sakane, Toshiko Muneishi and Toshikazu Hirao Chem. Commun., 2008, 765-767 ] such as
naphtosumanene [ Synthesis of Highly Strained π-Bowls from Sumanene Toru Amaya, Takuto Nakata and Toshikazu Hirao, Japan J. Am. Chem. Soc., 2009, 131 (31), pp 10810–10811 ] and
trisialsumanene [Communication Development of a Sila-Friedel−Crafts Reaction and Its Application to the Synthesis of Dibenzosilole Derivatives Shunsuke Furukawa, Junji Kobayashi and Takayuki Kawashima J. Am. Chem. Soc., 2009, 131 (40), pp 14192–14193 ][ Synthesis, structures and optical properties of trisilasumanene and its related compounds Tomoharu Tanikawa, Masaichi Saito, Jing Dong Guo and Shigeru Nagase Org. Biomol. Chem., 2011, 9, 1731-1735 ] have been described. Chiral sumanenes are of some interest with respect to inherent chirality,
[ Inherently chiral concave molecules—from synthesis to applications Agnieszka Szumna Chem. Soc. Rev., 2010, 39, 4274-4285 ] examples are chiral
trimethylsumanene [ Asymmetric Synthesis of a Chiral Buckybowl, Trimethylsumanene Shuhei Higashibayashi and Hidehiro Sakurai J. Am. Chem. Soc., 2008, 130 (27), pp 8592–8593 ] and a chiral sumanene cyclopentadienyl iron complex
[Sakane, H., Amaya, T., Moriuchi, T. and Hirao, T. (2009), A Chiral Concave-Bound Cyclopentadienyl Iron Complex of Sumanene. Angewandte Chemie International Edition, 48: 1640–1643. ]
See also
