Sulfimides are nitrogen analogues of sulfoxides. [1] In organic synthesis, they serve as useful intermediates [1,2] and have been applied as efficient ligands for metal catalysts. [3] Because of their unique biological properties, [1a, 4] sulfimides have also gained considerable attention in agricultural science and medicinal chemistry. As sulfoxides, sulfimides are chiral and have a stereogenic center at the sulfur atom if they originate from unsymmetrically substituted sulfides. Although sulfimides can be easily synthesized by various means, [1,5] their preparation in enantioenriched form is still challenging. The most prominent strategies involve the use of chiral auxiliaries [3a, 6] or reagents. [7] All of those, however, require stoichiometric amounts of chiral compounds that are usually prepared by multi-step syntheses.The field of catalytic asymmetric sulfimidation is scarcely explored, and only very few catalyst systems have been documented. For example, Uemura, Taylor and their coworkers disclosed the use of chiral copper(I)/bis(oxazoline) catalysts. [8] However, only sterically hindered aryl benzyl sulfides gave satisfying results. Subsequently, Katsuki and coworkers introduced chiral manganese(III)/salen [9] and ruthenium(II)/salen [10] (or salalen) [11] complexes as asymmetric sulfimidation catalysts. Excellent results were achieved, but the synthesis of salen ligands proved cumbersome.Inspired by the early work of Bach [5a,b] and encouraged by our findings that simple iron(II) and iron(III) compounds could effectively catalyze non-asymmetric sulfide imidations, [5h-j] we decided to focus our search on chiral iron complexes for asymmetric versions of such reactions. Herein, we report that iron(III)/PyBOX combinations are highly effective catalysts for the aforementioned transformations. Noteworthy, this is the first iron-catalyzed enantioselective sulfimidation reported to date, despite many other breakthroughs in asymmetric iron catalysis. [12,13] The asymmetric imidation of thioanisole (1 a) with N-(ptolylsulfonyl)imino phenyliodinane (PhI=NTs) in acetonitrile was selected as the benchmark reaction for our preliminary screening. Various catalysts formed in situ from chiral ligands and iron(III) acetylacetonate ([Fe(acac) 3 ], 3 a) were tested.