Remote modulation of amine basicity by a phenylsulfone and a phenylthio group

Marked basicity-lowering effects by a sulfone unit are documented in a series of phenylsulfone amines in which the sulfone unit is placed at different topological distances to an aliphatic amine group. An exponential attenuation of basicity shifts by increasing distance is observed. Smaller effects are exerted by a phenylthio group, in each case corresponding to those of a phenylsulfone unit one sigma-bond further away from the amino function.