ISSN:
0170-2041
Keywords:
[3 + 2] Cycloaddition
;
1H-Tetrazoles, 5-alkylidene-4,5-dihydro-
;
Azides, electrophilic
;
1,2,3,4-Tetrazines, 5-imino-1,4,5,6-tetrahydro-
;
Nitrogen 1,2-shift
;
Ring expansion
;
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
5-Imino-1,4,5,6-tetrahydro-1,2,3,4-tetrazines Formed from 5-Alkylidene-4,5-dihydro-1H-tetrazoles and Electrophilic Azides1)The electrophilic azides 1 react with the 5-alkylidenedihydrotetrazoles 8 already at low temperatures to produce high yields of the novel 5-iminotetrahydro-1,2,3,4-tetrazines 10 besides molecular nitrogen. The configurations of (Z)-10a, (E)-10c, (Z)-10d, and (E)-10h are elucidated by means of X-ray diffraction analyses. The formation of 10 is interpreted in terms of an initial [3 + 2] cycloaddition leading to the unstable spiro compounds 9. Ring opening of their dihydro-1,2,3-triazole ring generates the zwitterions 11 which lose molecular nitrogen with concomitant ring expansion of the dihydrotetrazole ring by a nitrogen 1,2-shift. The tetrazines 10a-c and e are also obtained when 8a is generated from the tetrazolium salt 7a and trapped „in situ“ by the azides 1a-c and e.
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jlac.199119910176
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