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Unanticipated formation of a novel octaazacyclodecane ring upon oxidation of a 1,1‐bis‐urazole
Author(s) -
Breton Gary W.,
Martin Kenneth L.
Publication year - 2018
Publication title -
acta crystallographica section c
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 17
ISSN - 2053-2296
DOI - 10.1107/s2053229618005211
Subject(s) - ring (chemistry) , chemistry , medicinal chemistry , organic chemistry
Tetrahydrotetrazoles are a little‐explored class of five‐membered heterocycles with four contiguous singly‐bonded N atoms. Recent work in our labs has demonstrated that urazole radicals are amenable to N—N bond formation via radical combination to form such a chain of four N atoms. Previously described 1,1‐bis‐urazole compounds appeared to be convenient precursors to the target tetrazoles via their oxidation to intermediate urazole diradicals, which upon N—N bond formation would complete the tetrazole framework. While oxidation proceeded smoothly, the novel 10‐membered octaaza heterocycle 7,7,18,18‐tetraacetyl‐4,10,15,21‐tetraphenyl‐1,2,4,6,8,10,12,13,15,17,19,21‐dodecaazapentacyclo[17.3.0.0 2,6 .0 8,12 .0 13,17 ]docosan‐3,5,9,11,14,16,20,22‐octone, C 42 H 32 N 12 O 12 , was obtained (36% yield) instead of the expected tetrazole product, as confirmed by X‐ray crystallography. Calculations at the (U)B3LYP/6‐311G(d,p) level of theory suggest that the desired tetrazoles have weak N—N bonds connecting the two urazole units.