Intramolecular C–H Amination Reaction Provides Direct Access to 1,2‐Disubstituted Diamondoids

We present a new approach to disubstituted diamondoids from corresponding carboxylic acids. A dirhodium‐acetate‐catalyzed (1 mol‐%) nitrene insertion reaction of sulfamides was, for the first time, applied to intramolecular C–H functionalization reactions of rigid tricyclic frameworks. This straightforward approach enables the effective and regioselective synthesis of a variety of diamondoid‐based cyclic sulfamidates, which are synthetically valuable building blocks. Reductive deprotection of the sulfamidate moiety leads to corresponding 1,3‐amino alcohol derivatives. Oxidation of the sulfamidate moiety by KMnO 4 provides access to 1,3‐keto alcohols or imines. Finally, we report the synthesis of Vildagliptin ® analogues as new antidiabetic drug candidates (DPP‐4 inhibitors).