Substitution at Tricoordinate Sulfur(IV). Rearrangement of Sulfinanilides to Anilino Sulfoxides

Article abstract of DOI:10.1021/jo00173a005

Seven N-methyl-N-aryl-p-toluenesulfinamides (1, 3-Me2NC6H4; 2, 3-MeOC6H4; 3, 4-MeOC6H4; 4, 3-MeC6H4; 5, Ph; 6, 3-ClC6H4; 7, 3-FC6H4), N-(3-methoxyphenyl)-p-toluenesulfinamide (8), and two N-methyl-N-aryl-methanesulfinamides (9, 3-Me2NC6H4; 10, 3-MeOC6H4) were prepared from the corresponding sulfinyl chloride and the substituted aniline.Sulfinanilides 2 and 7 were treated with alkyllithiums in vain attempts to induce rearrangement to the diaryl sulfoxides via endocyclic nucleophilic attack by carbon 2 of the aniline ring on sulfur.Instead, the alkyllithium cleaved the S-N bond to yield the aniline and alkyl p-tolyl sulfoxide.Upon treatment with gaseous HCl in chloroform, the sulfinanilides rearranged as follows: 1 gave 4-(dimethylamino)-2-(methylamino)-4'-methyldiphenyl sulfoxide (92percent yield), 2 gave 2-methoxy-4-(methylamino)-4'-methyldiphenyl sulfoxide (26percent yield) and 4-methoxy-2-(methylamino)-4'-methyldiphenyl sulfoxide (70percent yield), 4 gave 2-methyl-4-(methylamino)-4'-methyldiphenyl sulfoxide (71percent yield), 9 gave methyl 4-(dimethylamino)-2-(methylamino)phenylsulfoxide (20percent yield), and 10 gave methyl 2-methoxy-4-(methylamino)phenyl sulfoxide (5percent yield).Sulfinanilides 3 and 5-8 did not rearrange.A tentative mechanism for the rearrangement is proposed.