Butler, Richard N. and Hanniffy, John M. and Stephens, John C. and Burke, Luke A.
A Ceric Ammonium Nitrate N-Dearylation of N-p-Anisylazoles
Applied to Pyrazole, Triazole, Tetrazole, and Pentazole Rings:
Release of Parent Azoles. Generation of Unstable Pentazole,
-, in Solution.
JOC - Journal of Organic Chemistry, 73 (4).
The reaction of cerium(IV) ammonium nitrate (CAN) with a range of N-(p-anisyl)azoles in acetonitrile
or methanol solvents leads to N-dearylation releasing the parent NH-azole and p-benzoquinone in
comparable yields. The scope and limitations of the reaction are explored. It was successful with 1-(panisyl)
pyrazoles, 2-(p-anisyl)-1,2,3-triazoles, 2-(p-anisyl)-2H-tetrazoles, and 1-(p-anisyl)pentazole. The
dearylation renders the p-anisyl group as a potentially useful N-protecting group in azole chemistry. The
azole released in solution from 1-(p-anisyl)pentazole is unstable HN5, the long-sought parent pentazolic
acid. p-Anisylpentazole samples were synthesized with combinations of one, two, and three 15N atoms
at all positions of the pentazole ring. The unstable HN5/N5
- produced at -40 °C did not build up in the
solution but degraded to azide ion and nitrogen gas with a short lifetime. The 15N-labeling of the N3
obtained from all samples proved unequivocally that it came from the degradation of HN5 (tautomeric
forms) and/or its anion N5
- in the solution.
||The definitive version of this article is available at JOC - Journal of Organic Chemistry (2008) Vol.73 No.4 pp.1354-1364. DOI: 10.1021/jo702423z
||Ceric Ammonium Nitrate N-Dearylation; N-p-Anisylazoles; Pyrazole; Triazole; Tetrazole; Pentazole Rings; Parent Azoles; Unstable Pentazole; HN5/N5;
||Science & Engineering > Chemistry
Dr John Stephens
||22 Aug 2012 15:40
|Journal or Publication Title:
||JOC - Journal of Organic Chemistry
||American Chemical Society
Repository Staff Only(login required)
||Item control page