Pagodane is an organic compound with formula whose carbon skeleton was said to resemble a pagoda, hence the name. It is a polycyclic hydrocarbon whose molecule has the ''D''_2''h'' point symmetry group. The compound is a highly crystalline solid that melts at 243 °C, is barely soluble in most organic solvents and moderately soluble in benzene and

chloroform Chloroform, or trichloromethane, is an organic compound with chemical formula, formula Carbon, CHydrogen, HChlorine, Cl3 and a common organic solvent. It is a colorless, strong-smelling, dense liquid produced on a large scale as a precursor to ...

. It sublimes at low pressure. The name pagodane is used more generally for any member of a family of compounds whose molecular skeletons have the same 16-carbon central cage as the basic compound. Each member can be seen as the result of connecting eight atoms of this cage in pairs by four

alkane In organic chemistry, an alkane, or paraffin (a historical trivial name that also has other meanings), is an acyclic saturated hydrocarbon. In other words, an alkane consists of hydrogen and carbon atoms arranged in a tree structure in which ...

chains. The general member is denoted 'm''.''n''.''p''.''q''agodane where ''m'', ''n'', ''p'' and ''q'' are the number of carbons of those four chains. The general formula is then where ''s''= ''m''+''n''+''p''+''q''. In particular, the basic compound has those carbons connected by four methylene bridges (''m''=''n''=''p''=''q''=1), and its name within that family is therefore .1.1.1agodane.

Synthesis and structure

The compound was first synthesized by Horst Prinzbach and his associates in 1987, by a 14-step sequence starting from isodrin. In the process they also synthesized .2.1.1agodane and several derivatives. Prinzbach remarked that "the obvious need for he short name 'pagodane'can be readily understood in view of the von Baeyer/ IUPAC and Chemical Abstracts nomenclature", undecacyclo .9.0.0^1,5.0^2,12.0^2,18.0^3,7.0^6,10.0^8,12.0^11,15.0^13,17.0^16,20cosane. In carbon skeleton of pagodane, there can be distinguished many propellane-type fragments. The overall synthesis can be summarized as follows: The scheme depicted here may be shortened to 14 one-pot operations with 24% overall yield. Yet, this variation requires the use of tetrachlorothiophenedioxide instead of tetrachloro-dimethoxycyclopentadiene in two of the early steps. While lesser steps and higher yield look attractive at first sight, this approach had to be given up due to high cost and restricted availability of the dioxide.

Derivatives

Several derivatives are available, such as the diketone (melting point about 322 °C). Both .1.1.1agodane and .2.1.1agodane form divalent

cation An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

s in / . In these cations the electron deficiency is spread over the central cyclobutane ring. These dications were the first examples to show the phenomenon of σ-bishomoaromaticity which was subsequently studied by the Prinzbach group to great length. Pagodane is an isomer of dodecahedrane and can be chemically converted to it.

References

{{reflist, colwidth=30em , refs= Elegant Solutions: Ten Beautiful Experiments in Chemistry Philip Ball RSC 2005 Wolf-Dieter Fessner, Gottfried Sedelmeier, Paul R. Spurr, Grety Rihs, H. Prinzbach (1987), ''"Pagodane": the efficient synthesis of a novel, versatile molecular framework''. J. Am. Chem. Soc., volume 109 issue 15, pp. 4626–42 {{doi, 10.1021/ja00249a029 H. Prinzbach, F. Wahl, A. Weiler, P. Landenberger, J. Woerth, L.T. Scott, M. Gelmont, D. Olevano, F. Sommer, B. von Issendorff: C20 Carbon Clusters: Fullerene - Boat - Sheet Generation, Mass Selection, PE Characterization. Chem. Eur. J. 2006, 12, 6268-6280 , {{doi, 10.1002/chem.200501611 G. K. Surya Prakash (1998), ''Investigations on intriguing long lived carbodications''. Pure & Appl. Chem., volume 70 issue 10, pp. 2001–06
Online version
at iupac.org accessed on 2010-01-14. {{doi, 10.1351/pac199870102001 G.K.S. Prakash, V.V. Krishnamurthy, R. Herges, R. Bau, H. Yuan, G.A Olah, W.-D. Fessner, H. Prinzbach: .1.1.1 and .2.1.1agodane Dications: Frozen Two-Electron Woodward-Hoffmann Transition State Models. J. Am. Chem. Soc. 1988, 110, 7764-7772 Wolf-Dieter Fessner, Bulusu A. R. C. Murty, Horst Prinzbach (1987), ''The Pagodane Route to Dodecahedranes – Thermal, Reductive, and Oxidative Transformations of Pagodanes'' Angewandte Chemie International Edition in English Volume 26, Issue 5, pp. 451–52 {{doi, 10.1002/anie.198704511 Wolf-Dieter Fessner, Bulusu A. R. C. Murty, Jürgen Wörth, Dieter Hunkler, Hans Fritz, Horst Prinzbach, Wolfgang D. Roth, Paul von Ragué Schleyer, Alan B. McEwen, Wilhelm F. Maier (1987), ''Dodecahedranes from .1.1.1agodanes''. Angewandte Chemie International Edition in English, Volume 26, Issue 5, pp. 452–54 {{doi, 10.1002/anie.198704521 ''Stable carbocations. Part 267. Pagodane dication, a unique 2.pi.-aromatic cyclobutanoid system'' G. K. Prakash, V. V. Krishnamurthy, Rainer. Herges, Robert. Bau, Hanna. Yuan, George A. Olah, Wolf Dieter. Fessner, and Horst. Prinzbach Journal of the American Chemical Society 1986 108 (4), 836-838 {{doi, 10.1021/ja00264a046 Polycyclic nonaromatic hydrocarbons Cyclobutanes Substances discovered in the 1980s