Rhodium-catalyzed phenylation of N-arylsulfonyl aldimines with sodium tetraphenylborate or trimethyl(phenyl)stannane

The rhodium-catalyzed addition reactions of trimethyl(phenyl)stannane and sodium tetraphenylborate to N-phenylsulfonyl aldimines RCHNSO2Ph (R=alkyl and aryl) provided R(Ph)CHNHSO2Ph in high yields. A cationic and free phosphine complex [Rh(cod)(MeCN)2]BF4 was found to be an efficient catalyst for the addition of PhSnMe3, whereas [Rh(cod)(MeCN)2]BF4/dppb catalyzed the addition of Ph4BNa to various N-sulfonyl aldimines in dioxane at 90°C. The scope and limitations of the reactions, as well as the effect of varying the reaction conditions, are discussed.