| Spiropentadiene | |
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Spiro[2.2]penta-1,4-diene |
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Other names
Bowtiediene; Spiropenta-1,4-diene |
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| Identifiers | |
| CAS number | 1727-65-7 |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molecular formula | C5H4 |
| Molar mass | 64.09 g mol−1 |
| (verify) (what is: /?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Spiropentadiene, or bowtiediene, is a hydrocarbon with formula C5H4. The simplest spiro-connected cycloalkene, it is very unstable—decomposing even below −100 °C—due to its high bond strain and does not occur in nature. It was successfully synthesized in 1991 in the laboratory.[1][2]
Spiropentadiene was synthesised from bistrimethylsilylpropynone 1 by reaction with p-toluenesulfonylhydrazide to tosylhydrazone 2 followed by treatment with sodium cyanoborohydride to allene 3 and followed by two successive reactions with chlorocarbene generated from methyllithium and dichloromethane to spiro compound 5. Spiropentadiene was trapped in a liquid nitrogen trap after reaction with TBAF in a double elimination reaction.
The derivative dichlorospiropentadiene has been reported [3]. An all-silicon derivative (Si5 frame, tBuMe2Si side groups ) is also known [4]. In contrast to the carbon parent this compound is stable with a melting point of 216 to 218 °C. The angle between the two rings as measured by X-ray single-crystal analysis is 78°.
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