An unexpected copper catalyzed 'reduction' of an arylazide to amine through the formation of a nitrene intermediate

Hanjing Peng; Kednerlin H Dornevil; Alexander B Draganov; Weixuan Chen; Chaofeng Dai; William H Nelson; Aimin Liu; Binghe Wang

doi:10.1016/j.tet.2013.04.091

An unexpected copper catalyzed 'reduction' of an arylazide to amine through the formation of a nitrene intermediate

Tetrahedron. 2013 Jun 24;69(25):5079-5085. doi: 10.1016/j.tet.2013.04.091. Epub 2013 Apr 25.

Authors

Hanjing Peng^#¹, Kednerlin H Dornevil^#¹, Alexander B Draganov¹, Weixuan Chen¹, Chaofeng Dai¹, William H Nelson², Aimin Liu¹, Binghe Wang¹

Affiliations

¹ Department of Chemistry, Center for Biotechnology and Drug Design, and Center for Diagnostics and Therapeutics, Georgia State University, P.O. Box 3965, Atlanta, Georgia 30302-3965, USA.
² Department of Physics and Astronomy, Georgia State University, P.O. Box 4106, Atlanta, Georgia 30302-4106, USA.

^# Contributed equally.

Abstract

Azido nitrobenzoxadiazole (NBD) was observed to undergo a 'reduction' reaction in the absence of an obvious reducing agent, leading to amine formation. In the presence of an excess amount of DMSO, a sulfoxide conjugate was also formed. The ratio of these two products was both temperature- and solvent-dependent, with the addition of water significantly enhancing the ratio of the 'reduction' product. Two intermediates of the azido-NBD reaction in DMSO were trapped and characterized by low-temperature EPR spectroscopy. One was an organic free radical (S=1/2) and another was a triplet nitrene (S=1) species. A mechanism was proposed based on the characterized free radical and triplet intermediates.

Keywords: Azide; EPR; NBD; Nitrene; Reduction.

Abstract

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