The addition of arylboronic acids, ArB(OH)2, to N-phenylsulfonyl aldimines, RCH=NSO2Ph (R = alkyl, aryl, 1-alkenyl), giving R(Ar)CHNHSO2Ph was carried out at 95 °C in the presence of a rhodium catalyst. [Rh(cod)(MeCN)2]BF4 (3 mol%) was found to be the best catalyst for aryl aldimines and Rh(acac)(coe)2/i-Pr3P for alkyl and 1-alkenyl aldimines. The analogous reactions of arylboronic esters, such as 1,2-ethanediol and 1,3-propanediol ester, yielded the addition products in the presence of two equivalents of Et3N.