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The intramolecular C-H insertions of carbenes derived from 2-diazo-2-sulfamoylacetamides were studied. 2-Diazo-2-sulfamoylacetamides were first prepared from chloroacetyl chloride and secondary amines through acylation followed by sequential treatments with sodium sulfite, phosphorus oxychloride, secondary amines, and 4-nitrobenzenesulfonyl azide. The results indicate that: (1) 2-diazo-<i>N,N</i>-dimethyl-2-(<i>N,N</i>-diphenylsulfamoyl)acetamide can take the formal aromatic 1,5-C-H insertion in its <i>N</i>-phenylsulfonamide moiety to afford the corresponding 1,3-dihydrobenzo[<i>c</i>]isothiazole-3-carboxamide 2,2-dioxide derivative; (2) no aliphatic C-H insertions occur for 2-diazo-2-(<i>N,N</i>-dialkylsulfamoyl)acetamides; and (3) for 2-diazo-<i>N</i>-phenyl-2-(<i>N</i>-phenylsulfamoyl)acetamides, the formal aromatic 1,5-C-H insertion in the <i>N</i>-phenylacetamide moiety is favorable to afford the corresponding 3-sulfamoylindolin-2-one derivatives as sole or major products. The intramolecular competitive aromatic 1,5-C-H insertion reactions of 2-diazo-2-sulfamoylacetamides with aryl groups on both amide and sulfonamide groups reveal that the <i>N</i>-aryl substituents on acetamide are more active than those on sulfonamide. The chemoselectivity is controlled by electronic effect of the aryl group.