Nucleophiles from Group 14 C and Sn

The reaction with carbanions and anions derived from stannanes to afford C—C and C—Sn bonds constitutes one of the more representative examples. 

This approach using ArMgX bearing a leaving group was applied in radical/anionic S l-type polymerizations for preparation of oligoarenes [24]. The reaction of 16 with TEMPO as initiator afforded the poly(m-phenylene) 17 (Eq. 10.7)  

In this transformation, the homocoupling of the ArMgX reagents to biaryls (Ar-Ar) by oxidation with TEMPO was applied as initiation step. This homocouphng proceeds via a biaryl radical anion intermediate 18, which fragments at the C—I bond to give the radical 19 that initiates polymerization (Eq. 10.8) to yield 17 [25]  

carbanions derived from esters, Al,Al-disubstituted amides, thioamides, imides, and 0-cyanocarbonyl and 0-dicarboxylic compounds have been successfully used as nucleophiles to form new C—C bonds with aromatic substrates [9]. 

The photostimulated reaction of 1-iodonaphthalene 20 with a chiral-assisted imide enolate anion 21 in liquid ammonia is an interesting example of reaction from carbanion a to an EWG. This provides a stereoselective coupling of an aromatic radical with a nucleophile. In this reaction, the diastereomeric isomers of the substitution compound (22 and 23) are formed (43-64%), and the selectivity observed is highly dependent on the metal counterion used (LP, Na+, K+, Cs, Ti ). The highest stereoselectivity is found with LP at -78°C (d.r. 78/22%, S/R) and with TP at -33°C (d.r. 98%, S/R) (Eq. 10.9) [26]  

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