Aryl anions

Arenesulfinic acid, from ArNj 241 Aromaticity of boron hydrides 283 Arseno-de-diazoniation 275 Aryl anions 211... 

In these reaetions, the most reliable mechanism is considered to involve the initial metal-coordination at the nitrogen atom of the pyridine ring and the subsequent attack of an alkyl or aryl anion at the most probable cationic sites on the ring, namely, the 2- and/or 4-position of the ring. If a 2-halogen substituted pyridine is used, the nucleophilic anion attacks the 6-position. Thus, the addition is a more prefered reaction than the ipso-substitution as shown in reaction (29). The substitution of amide or phenyl-... 

In contrast to the Ni(dppe) (Ph) (Br) complex, Pd(PPh3)2(Ph)(Br) undergoes a single two-electron reduction followed by expulsion of the aryl anion (reaction... 

S. Bank, Aspects Mech. Organomet. Chem. [Proc. Symp.] 1978, 109-139 . .Effects of Steric Strain on the Preparation, Stability, and Reactions of Aryl Anions and Amines". 

Step 3 Completion of addition phase. The aryl anion abstracts a proton from the ammonia used as the solvent in the reaction. 

C—X Disconnection into an aryl anionic site (methods 1(a) and 2), e.g. 

A silyl or aryl anion-stabilising group at the terminus of the alkyne is essential for rapid exodig cyclisations other than those of alkyllithiums 177178 aryl and vinyllithiums will cyclise onto alkynes bearing alkyl substituents only very slowly even in the presence of TMEDA.180 The allenyllithium cyclisation from 407 is a remarkable example of a cyclisation initiated by... 

A photoexcited anion also plays a role in the photoelectrocatalytic reduction of 4-chlorobiphenyl using the anion radicals of anthracene and 9,10-diphenylanthracene409. The anion radicals were electrochemically generated and excited by means of visible light. Formation of the aryl anion radical then takes place either by direct electron transfer or by... 

Obviously, in the precursor immonium compounds 26,27 the phosphorus bears enough partial positive charge to allow easy attack by aryl anions. Along similar lines of argument an even simpler synthetic procedure could be found in using analoguous p-toluenesulfonylimine (tosylimine) derivatives 2943), which had the appropriate polarization of the P=N double bond already built in4. ... 

It is important that you see for yourself why an aryl anion is a more stable intermediate than an aryl cation. Having an empty sp2 orbital means that there are electrons in a higher energy) p orbital that would be more stable in the sp2 orbital. Having a full sp2 orbital on the other hand leaves no empty low-energy orbitals. 

---