Selectivity monoarylation

Benzanilide, which is a structural relative of benzyl phenyl ketone, is diarylated on the benzoyl moiety using aryl bromides or triflates [120]. iV-Arylation [121] is not observed under the given conditions. AT-(2-Naphthoyl)aniline undergoes monoarylation selectively at the 3 position (Eq. 50). This maybe attributed to steric reasons. 

Figure 2 Conversion of guaiacol (X), selectivity to vanillols (o), to monoaryl by-products (v) and to diaryl by-products (ct) as functions of the Si/AI ratio of H-mordenites. Reaction time, 2 h other reaction conditions as in Figure 1. H-mordenites were supplied by Engelhard.

Bipyridine was also en efficient ligand for the nickel-catalyzed carbon-nitrogen bond forming reactions. Using piperazine as a bifunctional amine, its monoarylation and diarylation were both achieved selectively with... 

Ipaktschi and Sharifl reported the palladium-catalyzed synthesis of 2,7-diamino fluorenones by two indirect routes due to the base sensitivity of fluorenones [182]. First, 2,7-dibromofluorene was reacted with secondary amines, and subsequent oxidation of the product formed the diaminofluorenone. Alternatively, reaction of ami-nostannanes derived from secondary amines with 2,7-dibromofluorenone gave yields of the fluorenone ranging from 42 to 58%. Beletskaya has used the DPPF-ligated palladium system to conduct selective monoarylation of ethylene diamine, diethylene triamine, triethylene tetra-amines, and 2,2-dimethyl butane-1,3-diamine [183]. 

Aliphatic nitro compounds can be arylated using appropriate catalyst systems. For example, the reaction of nitroethane using a bulky phosphine affords the corresponding monoarylated product with good selectivity and yield (Eq. 32) [15]. The intramolecular version of a-arylation of nitro compounds has also been reported (Eq. 33) [59]. 

Scheme 2 Selective palladium-catalyzed ammonia monoarylation employing the JosiPhos ligand CyPF-tBu (LI)...

Scheme 3 Scope of the [Pd(cinnamyl)CI]/BippyPhos (L2) catalyzed synthesis of substituted indoles and related heterocyclic derivatives involving selective ammonia monoarylation...

Air-stable biaryl monophosphine ligands developed by Buchwald and co-workers have played a central role in the advancement of palladium-catalyzed cross-coupling reactions, including BHA chemistry the utility of appropriately configured ancillary ligands of this type in the selective monoarylation of ammonia has been examined. Following on preliminary experimentation that established the capability of the Pd2(dba)j/L3 catalyst system (dba=dibenzylideneacetone) to promote the monoarylation of ammonia at elevated temperature Tsvelikhovsky... 

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