The reactions of 3-phenyl-1-azabicyclo[1.1.0]butane with α-chlorosulfenyl chlorides and sulfinyl chlorides lead to the corresponding sulfenamides and sulfinamides, respectively, which possess an azetidine ring. It is proposed that a two-step mechanism occurs involving an intermediate carbenium ion, which is formed by the addition of the electrophile at the N-atom and cleavage of the N(1)C(3) bond.