83538-41-4Relevant academic research and scientific papers
Reactions of Acceptor-substituted Cyclononatetraenyl Anions with Electrophiles: Donor-substituted Nonafulvenes and their Properties
Boche, Gernot,Heidenhain, Frank,Staudigl, Brigitte
, p. 3191 - 3202 (2007/10/02)
From the acceptor-substituted cyclononatetraenyl anions 4α - δ- were prepared the 10-donor-substituted nonafulvenes 2f - i, while 2c,d were synthesized from the annulene anion (1-).A comparison of the thermal and spectral properties of these nonafulvenes revealed a close resemblance to the unsubstitued, olefinic nonafulvene (2b). 10,10-Bis(dimethylamino)nonafulvene (2a), therefore, is unique among the nonafulvenes: All experimental results as well as a comparison with 4'α-Na+ 4α-Na+ suggest under certain solvent and temperature conditions the existe nce of a dipolar conformation with an orthogonal orientation of the "substituent" and the annulene anion ring (2a+-).In the case of 2c,d,f - i as well as 10,10-bis(methylthio)nonafulvene the electronic and steric prerequisites are not favorable for such an alternative.If 4α-Li+ or 4'α-K+ were reacted with acetyl chloride, the electrophile predominantly attacked the oxygen atom of the ambident anion, as was the case with trimethylsilyl chloride.Protonation, on the other hand, led to ketones.Thus under kinetically controlled conditions we obtained the less stable 6a; the thermodynamically controlled reaction resulted in the formation of the conjugated 6b.
