ISSN:
0009-2940
Keywords:
1-Aza-2-azoniaallene cations
;
Isocyanates
;
4,5-Dihydro-5-oxo-1,2,4-triazolium salts
;
Cinnolinium salts
;
Cycloadditions
;
Calculations, AM1
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
1-Aza-2-azoniaallene salts 3, prepared in situ from geminal chloroalkylazo compounds 2 with Lewis acids, react with isocyanates 4 to give 4,5-dihydro-5-oxo-3H-1,2,4-triazolium salts 6 and 4,5-dihydro-5-oxo-1H-1,2,4-triazolium salts 7, respectively. The intramolecular cyclization of 3u opens a new route to cinnolinium salts 11. Allenes 3 react with isobutene to give pyrazolium salts 8. According to AM1 calculations the cycloadditions of 3 to isocyanates proceed in two steps via acylium salts 5 as intermediates. Mechanistically, the rearrangements 6 → 7 resemble Wagner-Meerwein rearrangements rather than pericyclic [1,5]-sigmatropic shifts.
Additional Material:
1 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19941270524
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