Arylboronic nucleophilic aromatic substitutions

Support-bound benzimidazoles can be N-arylated by treatment with arylboronic acids in the presence of Cu(OAc)2 (Entry 3, Table 15.15). Benzimidazolones, which can be prepared from resin-bound 1,2-diaminobenzenes and di-iV-succinimidyl carbonate (Entry 8, Table 15.14), can also be N-alkylated on insoluble supports (Entry 4, Table 15.15). Benzimidazole-2-thiones, on the other hand, are generally cleanly S-alkylated (Entry 5, Table 15.15). Examples of amination by aromatic nucleophilic substitution at resin-bound halopurines are given in Section 10.1.2. 

As seen with pyridazines, palladium catalyzed coupling reactions were also frequently applied in the phthalazine field. For example, commercially available 1,4-dichlorophthalazine 185 was aminated to give 186 in good yield by aromatic nucleophilic substitution with A -methylpiperazine <01S699>. Then, 186 was coupled with various substituted arylboronic acids to obtain 187 by Suzuki-type cross-coupling reactions. Best results were obtained with electron-donating substituents on the arylboronic acid. 

Diethoxy a-hydroxy-benzylphosphonate has been reported to undergo nucleophilic substitution with primary amines to give a-aminophosphonates (Scheme 184) " Primary aromatic amines have been prepared from arylboronic acids in the presence of 0-(2,4-dinitrophenyl)hydroxylamine. " Reaction of iV-t-butanesulfinyl a-haloimines with alkoxides has been reported to give iV-t-butanesulfinyl 2-amino acetals that are precursors for TMSOTf-promoted synthesis of iV-protected a-amino aldehydes and ketones and for the HCl-promoted synthesis of 2-amino acetal hydrochlorides and a-amino ketone and a-amino aldehyde hydrochlorides (Scheme 185). " ... 

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