Synthesis of substituted dibenzophospholes. Part 2. Syntheses of intermediate biphenyls and quaterphenyls

A general procedure for synthesis of 4″,6′-dialkoxy-2′,2″-diamino-m-quaterphenyls has been established. Copper(I) t-butoxide is used to prepare 2,6-dinitrobiphenyls from 1,3-dinitrobenzene and aryl iodides. One of the nitro-groups is then exchanged for a methoxy-group by sodium methoxide in hexamethylphosphoramide; the resulting 2-methoxy-6-nitrobiphenyls are then iodinated in the 5 position. Ullmann coupling then gives the dinitroquaterphenyls which are reduced to the diamines. An alternative route from 2,2′,4,4′-tetranitrobiphenyl was explored; arylation was easy but alkoxydenitration was indiscriminate. Some 71 new derivatives of biphenyl, terphenyl, and quaterphenyl are reported.