Regiospecific Synthesis of Aromatic Compounds via Organometallic Intermediates. 3. n-Alkyl-Substituted Benzene

Article abstract of DOI:10.1021/jo00177a018

High molecular weight tri- and tetra-n-alkylbenzenes have been synthesized by the cross-coupling of the appropriate chlorinated benzenes with long-chain n-alkylmagnesium bromides using (1,2-bis(diphenylphosphino)ethane)nickel(II)chloride as catalyst.The reactions proceeded without any positional scrambling or alkyl group isomerization.A new method is described for the preferential substitution of one chlorine atom by an n-alkyl group in 1,3,5-trichlorobenzene.The reaction between an n-alkylmagnesium bromide and 1,3,5-trichlorobenzene catalyzed by Nickelacetylacetonate at low temperature and in tetrahydrofuran solvent favors monosubstitution.The cross-coupling reactions of these n-alkyldichlorobenzenes with other n-alkylmagnesium bromides, in the presence of NiCl2(dppe), proceeded at a much slower rate than those of 1,3,5-trichlorobenzene to yield the asymmetric 1,3,5-tri-n-alkylbenzenes.