ISSN:
1434-193X
Keywords:
Nitrogen heterocycles
;
Nucleophilic additions
;
Novel recyclization
;
Semiempirical calculations
;
5-Aminoindolizine
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
2-Aryloxazolo[3,2-a]pyridinium perchlorate, 1a, and its 5-methyl homologue, 1b, undergo quite different ring transformations when reacting with piperidine. For 1a the opening of the pyridine fragment occurs with formation of the isomeric aminobutadienes 2 [with (1E,3E)-configuration] or 3 [(1E,3Z)-isomer], depending on the temperature, whereas 1b undergoes an unexpected recyclization of the oxazolium ring involving the methyl group to form the 5-aminoindolizine 4. 1a and 1b undergo an opening of the 5-membered ring when reacting with alkali. These results are explained by quantum chemical SINDO1 calculations, which give the energies of the isomeric C5- and C8a-adducts with NMe2 and HO groups.
Type of Medium:
Electronic Resource
Permalink
