Heteroatom-stabilized alkylation

Terminal monoalkenes were alkylated by stabilized carbanions (p a 10-18) in the presence of 1 equiv. of palladium chloride and 2 equiv. of triethylamine, at low temperatures (Scheme l).1 The resulting unstable hydride eliminate to give the alkene (path b), or treated with carbon monoxide and methanol to produce the ester (path c).2 As was the case with heteroatom nucleophiles, attack at the more substituted alkene position predominated, and internal alkenes underwent alkylation in much lower (=30%) yield. In the absence of triethylamine, the yields were very low (1-2%) and reduction of the metal by the carbanion became the major process. Presumably, the tertiary amine ligand prevented attack of the carbanion at the metal, directing it instead to the coordinated alkene. The regiochemistry (predominant attack at the more sub-... 

A rare species of salts consisting of a heteroatom-stabilized carbocation and a heteroatom-stabibzed carbanion has been formed by deprotonating methyl (Z)- or (E)-3-hydroxy-2,3-dimesitylpropenoate with tetrakis(dimethylamino)methane the resonance stabilization of the cation [(CH3)2N]3C+ and enolate anion, which is of E-configuration exclusively, since the guanadinium ion is incapable of forming a chelate, prevents a spontaneous O- or C-alkylation.12... 

Due to resonance stabilization and their higher nucleophilicity, heteroatoms stabilize the growing carbenium ions better than alkyl and aryl groups do N-vinyl carbazole is more reactive than vinyl ethers because of nitrogen s higher nucleophilicity. However, the reactivity of the growing carbenium ions follows the opposite order shown above, with the most stable... 

Alkylations of Other Heteroatom-stabilized Carbanions OEt 3 OEt Bu Li, 2 equiv. 

Reports on organolithium compounds with internal heteroatom stabilization and their reactions with alkylating agents7 12 -14 are informative for stereoselective protonations and deuter-ations. 

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