Intermolecular Metal‐Free Cyclopropanation and Aziridination of Alkenes with XH 2 (X=N, C) by Thianthrenation**

Abstract Three‐membered cyclic structures are widely existing in natural products and serve as enabling intermediates in organic synthesis. However, the efficient and straightforward access to such structures with diversity remains a formidable challenge. Herein, a general and practical protocol to aziridines and cyclopropanes synthesis using free XH 2 (X=C or N) with alkenes by thianthrenation is presented. This metal‐free protocol features the direct aziridination and cyclopropanation with unprotected XH 2 . Free sulfonamides, amides, carbamates, amines, and methylene with acidic protons, are good precursors, providing an attractive alternative for straightforward synthesis of aziridines and cyclopropanes from easily available starting materials.