Synthesis of 1‐Pyrroline by Denitrogenative Ring Expansion of Cyclobutyl Azides under Thermal Conditions

Abstract

We herein report an efficient and systematic synthesis of 1-pyrrolines from cyclobutyl azides under thermal and neutral conditions. The reaction proceeded without any additional reagents, and nitrogen was generated as the sole by-product. Furthermore, the generated 1-pyrrolines could be continuously transformed into pyrroles, N-Bocamines, and oxaziridines in an one-pot manner.

Electrocatalytic conversion of ω-azido carboxylic acids to 1-pyrrolines via a combined process of oxidative decarboxylation and intramolecular Schmidt rearrangement

“…According to the literature, we converted 2a into pyrrole 3 by adding Pd/C to the reaction using xylene as the solvent (Scheme 2a). 56 Treatment of 2e with m -chloroperbenzoic acid resulted in CN epoxidation, and the bicyclic oxaziridine 4 was afforded in 67% yield (Scheme 2b). 57 Enamide 5 was prepared in a yield of 94% by reacting the cyclic imine 2e with trifluoroacetic anhydride (Scheme 2c).…”

Enantioselective Synthesis of Secondary Amines by Combining Oxidative Rearrangement and Biocatalysis in a One-Pot Process

“…13 1 H NMR data corresponds with literature data. 22 4,5-Dihydro-2-methyl-3H-1-benzazepine (2b). In analogy to the synthesis described in ref 11, a mixture of amine 1b (32 mg, 0.2 mmol) and Cs 2 CO 3 (169 mg, 0.52 mmol) in methanol (4.2 mL) in an argon atmosphere was prepared.…”

“…rate = 1 mL min −1 , l = 220 nm) t R = 8.1 min (minor), 11.3 min (major).1 H NMR (500 MHz, CDCl 3 ) δ 7.39 (dd, J = 8.0, 1.6 Hz, 2H), 7.34 (dd, J = 8.5, 6.7 Hz, 2H), 7.28−7 22. (m, 1H), 4.19−4.09 (m, 1H), 3.24 (ddd, J = 10.1, 7.8, 5.2 Hz, 1H), 3.04 (ddd, J = 10.1, 8.2, 6.6 Hz, 1H), 2.22 (dtd, J = 12.4, 7.7, 4.7 Hz, 1H), 2.01−1.81 (m, 2H), 1.71 (ddt, J = 12.4, 9.3, 7.8 Hz, 1H).…”

From Cycloalkanols to Heterocycles via Nitrogen Insertion

“…After a consecutive 1,2-Stieglitz shift, pyrrolidene structures can be obtained. There is evidence that the envisioned rearrangement of cyclobutanes to pyrrolidenes can be triggered by oxidation of an already existing primary amine adjacent to the ring, by the thermal decomposition of cyclobutyl azides or by transition-metal-catalyzed approaches . Whereas the preparation of primary amines is often tedious and the handling of azides is inherently hazardous, cyclobutanols resemble a promising starting point, which, in turn, can be easily accessed via Grignard addition to commercially available cyclobutanone.…”