The microwave-assisted synthesis of 5-substituted 1H-tetrazoles via [3+2] cycloaddition over a heterogeneous Cu-based catalyst: application to the preparation of 13 N-labelled tetrazoles

• Published in: New journal of chemistry Vol. 41; no. 16; pp. 8084 - 8091
• Main Authors: Joshi, Sameer M., Mane, Rasika B., Pulagam, Krishna R., Gomez-Vallejo, Vanessa, Llop, Jordi, Rode, Chandrashekhar
• Format: Journal Article
• Language: English
• Published: 2017
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/C7NJ00568G

The [3+2] cycloaddition between various nitriles and sodium azide proceeds smoothly in the presence of a new Cu II catalyst in N -methyl-2-pyrrolidone (NMP) to give the corresponding 5-substituted 1 H -tetrazoles. The desired tetrazoles were obtained in high yields within 3–30 min by employing controlled microwave heating. The reaction most probably proceeds through the activation of the nitrile groups by the Cu II species, followed by a successive [3+2] cycloaddition with the sodium azide. The good performance of the catalyst enabled the preparation of selected tetrazoles labelled with the positron emitter nitrogen-13 even under conventional heating. The short reaction time, simple work-up procedure, and recyclability of the catalyst are advantages of the method reported here.