Synthesis of Benzoylbenzoic Acids Substituted Anthraquinones and Related Materials.

摘要

At-100 deg a bromine or iodine atom attached to an aromatic nucleus can be replaced rapidly through halogen-metal exchange with butyllithium. Since at this low temperature many functional groups show a surprising unreactivity toward organolithium reagents, it has been found possible to generate many phenyllithium reagents having a functional group at the ortho, meta or para position. Functionalized phenyllithium reagents have great synthetic utility. Reaction with electrophiles, such a methyl iodide, bromine, benzaphenone, cyclohexonone, phthalic anhydride, benzoate esters, diphenyl disulfide or ethylene oxide replaces the aryl lithium atom resulting in a benzene ring with two functional groups. Usually, allowing the functionalized aryllithium to warm up results in an interaction between the lithium atom and the functional group. A useful example of such an interaction is the self condensation of lithium ortho-lithio benzoates to yield ortho-benzoylbenzoic acid.