Sulfinamides are traditionally produced by the reaction of sulfinyl chlorides with primary or secondary amines.  They also arise by the addition of Grignard reagents to sulfinylamines, followed by protonation:
:RMgX  +  RN=S=O  →   RS(O)(NRMgX)
:RS(O)(NRMgX)  +  HO  →  RS(O)(NRH)  +  "MgX(OH)"
Yet another route entails peracid-oxidation of sulfenylphthalimides, which gives sulfinylphthalimides.