Tricyclo pentane synthesis

Molecule 2, CsHg The next molecule in the (conceptual ) hydrogen-removal series, 2, tricyclo[1.1.1.0 ]pentane, is almost always known as [l.l.l]propellane (Fig. 13.1). It too also represents a well-known compound, with ca. 180 references in Chemical Abstracts as of early 2007. Let us note at the outset that its two bridgehead atoms are tetracoordinate carbons with a highly unorthodox umbrella (Chapter 12, Figs. 12.7 and 12.8) disposition of their bonds. The first preparation was reported in 1982 by Wiberg and Walker [12], who made it by debromination of l,3-dibromobicyclo[l.l.l]pentane with i-butyllithium. A subsequent, more practical synthesis, by Szeimeis and coworkers [13] from the commercial compound... 

Based on the preceding procedure, the same group investigated the synthesis of novel organometallic cyclynes with expanded bicyclo[1.1.0]-butanc and tricyclo[2.1.0.0]-pentane topology (Figure 54). ... 

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