ORGN 545 |
| The rich synthetic protocols involving benzyne have been expanded to include the next (in terms of size) annulyne, [8]annulyne. For example, [8]annulyne will dimerize to form bi-[8]annulenylene in a manner that is analogous to the dimerization of benzyne to form by-[6]annulenylene (biphenylene). Both [6]annulyne and [8]annulyne are very reactive materials. However, the larger annulynes are much more ‘tame.' Only one isomer of o-benzyne ([6]annulyne or 1,2-didehydrobenzene) exists, but the dehydro analogue of the ‘ring-opened double benzene,' [12annulyne, was generated in three isomeric forms, two of which exhibit a weak paratropic ring current in their 1H-NMR spectra and are oxygen sensitive. In an analogous fashion a number of dehydroannulenes can be generated via the simple condensations of non-cyclic diynes. Further, vairation of the ion association charictaristics of the solvent system can suppress the formation of dehydroannulenes and promote the formation of the very illusive alenalenes, e.g. heptalene. |
|
ACS Award for Research at an Undergraduate Institution: Symposium in Honor of Cheryl D. Stevenson
8:15 AM-11:50 AM, Wednesday, March 28, 2007 McCormick Place Lakeside -- Room E451A/B, Level 4, Oral
Division of Organic Chemistry |