A sulfur neighbouring-group participation N-alkylation method is presented, which enables the simultaneous C–O cleavage, C–S immigration and C–N formation performed in a metal free system. The method has considerable generality and proceeds with excellent selectivity. Particularly noteworthy is the finding that the synergetic mechanism attributes to enhance both chemoselectivity and regioselectivity for this C–N coupling, which is distinguished from traditional nucleophilic mechanism.