Amine Salt–Catalyzed Synthesis of 5-Substituted 1H-Tetrazoles from Nitriles

Abstract

The [3 + 2] cycloaddition reaction between sodium azide and various organic nitriles proceeds smoothly in the presence of amine salts as catalyst in dimethylformamide. The corresponding 5-substituted 1-H tetrazoles were obtained under mild condition in good to excellent yields. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.

Keywords:

• Amine salt catalyst
• azide
• [3 + 2] cycloaddition
• heterocycles
• tetrazole

ACKNOWLEDGMENTS

We thank the State Key Laboratory of Materials-Oriented Chemical Engineering Foundation support of this work. We also thank Xiaoming Ren for his important contribution in the sample analysis of this work.

Notes

^a Reaction conditions: benzonitrile (10 mmol), NaN₃ (12 mmol, 0.78 g), catalyst (10 mmol), solvent (20 ml), 110 °C, reaction time (8 h).

^b Yield of isolated products. Structures confirmed by comparison of IR and ¹H NMR with those of authentic materials.

^c Catalyst structure A, B, and C (Scheme 1).

^d Hexadecyl trimethyl ammonium bromide (CTAB).

^e Reaction carried out with NaN₃ (7 mmol): Py·HCl (10 mmol), yield 58%; NaN₃ (12 mmol): Py·HCl (10 mmol), yield 84%; NaN₃ (15 mmol): Py·HCl (10 mmol), yield 93%.

^a Reaction conditions: aromatic nitrile (10 mmol), NaN₃ (12 mmol, 0.78 g), pyridine hydrochloride (0.01 mol, 1.15 g), and DMF (20 ml).

^b Yield of isolated products.

^a Reaction conditions: nitrile (10 mmol), pyridine hydrochloride (0.01 mol, 1.15 g), and NaN₃ (12 mmol, 0.78 g) in DMF (20 ml) for 1c–3c, NaN₃ (30 mmol, 1.95 g) in DMF (30 ml) for 5c–8c.

^b Isolated yield.

^c Glacial acetic acid (30 ml) as solvent.

^d Water (30 ml) as solvent.