Suzuki arylation of 2-halogeno and 2,7-dihalogeno derivatives of 1,8-bis(dimethylamino)naphthalene(proton sponge)was carried out.It was shown that the sterically hindered nature of the starting compounds in combination with the enhanced reactivity of their peri-NMe2 groups allow to obtain the target 2-aryl and 2,7-diaryl derivatives in 20–34% yields only.In most cases,a tandem Pd-catalyzed hydrodehalogenation/N-demethylation process was predominant.The latter,however,makes it possible to obtain yet unknown and synthetically valuable 2-aryl-N~1,N~1,N~8-trimethyl-1,8-diaminonaphthalenes(21–50 %),which can be easily converted into the corresponding proton sponges by conventional N-methylation.Using the literature data on 2,7-disubstituted derivatives of the proton sponge as a background together with the XRD and basicity measurements performed in this work,a comprehensive analysis of the socalled"buttressing effect"in 2-aryl-and 2,7-diaryl-1,8-bis(dimethylamino)naphthalenes,along with previously unknown 2,6-diphenyl-N,N-dimethyl-p-toluidine has been carried out for the first time.
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