Theoretical calculation studies on the rearrangement mechanisms of arenesulfenanilides to generate o- and p-aminodiphenyl sulfides

Silver-Catalyzed para-Selective Sulfenyl Group Transfer Reactions of N-Sulfenylanilides

Silver-catalyzed reactions of N-sulfenylanilides afforded the corresponding p-sulfenylanilides in good to high yields with good para selectivity. The transformation has a high compatibility of functional groups, such as ester, bromo, and iodo groups. Mechanistic studies indicate that the rearrangement reaction proceeds through intermolecular transfer of the sulfenyl group.

Diverse and chemoselective sigmatropic shift rearrangements of multisubstituted N,O-diarylhydroxylamines

N,O-Diarylhydroxylamines generally favor the [3,3] sigmatropic shift rearrangement. Possible N/O[1,3] sigmatropic shift rearrangements of multisubstituted N,O-diarylhydroxylamines were investigated experimentally with rationally designed substrates, which were generally in situ prepared from suitable nitroaryl halides and N-arylhydroxylamines via aromatic nucleophilic substitution. The results indicate that both N- and O-(2,4,6-trimethylphenyl)hydroxylamines still favor the [3,3] sigmatropic shift followed by tautomerization rather than N[1,3] and O[1,3] sigmatropic shifts and the rearranged products of N-(2,4,6-trimethylphenyl)hydroxylamines further undergo an intramolecular nucleophilic addition to afford dibenzo[b,d]furan-4a(9bH)-amine derivatives, while N-(4-mono- and 3,5-disubstituted phenyl)-O-(2,4,6-trinitrophenyl)hydroxylamines favorably first undergo the O[1,3] sigmatropic shift followed by tandem Smiles rearrangement and amide/ester exchange reactions, generating 2-arylaminoaryl benzoate derivatives. N-Phenyl-O-(2,4,6-trinitrophenyl)hydroxylamines undergo tandem double O[1,3] sigmatropic shift rearrangement to produce formal O[1,5] shift products. However, O-(2,6-dinitrophenyl)-N-(4-substituted phenyl)hydroxylamines undergo tandem O[1,3] and double [3,3] sigmatropic shift rearrangements to give formal 3,5-shift products. The proposed mechanism is rationalized by density functional theory (DFT) calculations. The current investigation provides not only a comprehensive understanding of the chemoselective sigmatropic shift rearrangements of N,O-diarylhydroxylamines, but also some novel synthetic strategies for dibenzo[b,d]furanamines, diarylamines, diaryl ethers, 2'-amino-[1,1'-biphenyl]-2(1H)-one, and 2'-amino-[1,1'-biaryl]-4-ol derivatives.

A four-step cascade reaction involving O[1,3] sigmatropic shift and Smiles rearrangements as key steps

4-Nitroaryl halides and N-acyl-N-arylhydroxyamines undergo cascade aromatic nucleophilic substitution-O[1,3] sigmatropic shift-Smiles rearrangement-amide and ester exchange reaction, affording 2-((4-nitroaryl)amino)aryl carboxylates.

The selective synthesis of N-arylbenzene-1,2-diamines or 1-arylbenzimidazoles by irradiating 4-methoxy-4'-substituted-azobenzenes in different solvents

The solvent-controllable photoreaction of 4-methoxyazobenzenes to afford 1-aryl-1H-benzimidazoles or N-arylbenzene-1,2-diamines has been studied. The irradiation of 4-methoxyazobenzenes in DMF containing 0.5 M hydrochloric acid provided N²-aryl-4-methoxybenzene-1,2-diamines as the major product, while irradiation in acetal containing 0.16 M hydrochloric acid led to 1-aryl-6-methoxy-2-methyl-1H-benzimidazoles as the major product. A possible reaction mechanism explaining the selectivity was also discussed.

A solvent-controllable photoreaction involving 4-methoxyazobenzenes has been developed to synthesize 1-aryl-1H-benzimidazoles or N-arylbenzene-1,2-diamines in moderate to good yields.