Iodoaniline Dependent Formation of N-Aroylguanidines versus 2-Aminoquinazolinones from Palladium(0) Catalysed Aminocarbonylation of N-Arylguanidines

Abstract

Abstract A family of N,N´-diaryl-N″-(pyridine-2-ylmethyl)guanidines (B) were prepared in 70%−92% yields and subjected to palladium(0) catalyzed aminocarbonylation reactions with aryl iodides using CsOH/CHCl3 mixture as CO surrogate to afford the corresponding N-aroylguanidines (C) in 70%−93% yields. A gram scale synthesis was reported for a representative example. When the aforementioned reaction was carried out with 2-iodoaniline as an electrophile, either a mixture of two distinct 2-aminoquinazolinones (D and E) or one of these 2-aminoquinazolinones are formed. The scope of guanidines and aryl iodides were explored for both of the above-mentioned reactions. The role of directing group in the substrates upon the successful aminocarbonylation of guanidines, B is outlined. When the -C(O)Ar unit in N-aroylguanidines contain 2-aminophenyl unit, a spontaneous cyclisation occurs to afford D or E or a mixture of both. The reactions of a pair of N-aroylguanidines, C with PhI(OAc)2 afforded 2-aminobenzimidazoles, T with unanticipated core. Plausible mechanisms of formation of C, D, E and T are outlined.