ethanol under reflux led to the formation of oxetane 6 following the literature procedure. We obtained the product in a 77% yield after distillation. Cyclization of the latter with sodium hydride in DMF smoothly proceeded at room temperature to provide the spirocyclic compound 3 with a 97% yield. No purification was needed at this step. Finally, the reduction of the nitrile group with LiAlH4 gave the desired amine 3a in a slightly lower yield of 69% yield. After the standard workup, we added MeOtBu to the reaction mixture, and the white solid was isolated by simple filtration. Also, we subsequently converted it into a more stable on-air crystalline hydrochloride salt. Importantly, we optimized the whole reaction sequence to avoid column chromatography at any step. This tactic allowed us to easily obtain 40 g of product 3a*HCl in one run. The structure of the product was confirmed by X-Ray analysis. Scope. Moving forward, we studied the generality of the developed method. During the process, we also found that the reduction of nitrile 3 could be alternatively performed with NaBH4/CoCl2 (cat.) in methanol under reflux in 52% yield. In studying the scope, we allowed some flexibility and used both protocols. The reduction and the recyclization steps tolerated well various substituents on the aromatic core (Scheme 4). Among them were the alkyl groups (7a-10a), fluorine (15a-17a), chlorine atoms (19a-22a), methoxy groups (11a, 12a), and trifluoromethyl groups (18a). The reaction was also compatible with the substituted thiophene (23a), pyridine (24a), and even the ester group (25a). Importantly, products with aliphatic (26a-34a) and even N-Boc groups (35a) were obtained as well. Most compounds were isolated as free bases, however, in some cases, we converted them into crystalline hydrochloride salts. All syntheses were performed on a gram scale, and products 3a and 26a were also synthesized in 40 to 50-gram amounts. The structure of compounds 11a*HCl and 15a*HCl was confirmed by X-Ray analysis (Scheme 4). Mechanism. Even though we had a solid protocol for 3-azabicyclo[3. 1.1]heptanes in hand, out of scientific curiosity, we wanted to understand the mechanism of the reaction. Did the reduction of nitrile 3 into product 3a proceed via amine 4? The problem was that we never could isolate this invisible intermediate. Reducing the reaction time only led to a mixture of the product and the starting material. Luckily, we could synthesize azide 36 (please, see SI for its preparation). Its mild Staudindger reduction with PPh3 in THF at room temperature led to the formation of amine 4 as a free base (Table ). The compound formed with ca. 90% purity, but we could fully characterize it by NMR and HRMS.