ISSN:
0947-3440
Keywords:
4H-Pyrazoles
;
[4 + 2] Cycloaddition with reversed electron demand
;
[m]Diaza[n]norbornenes
;
High-pressure reactions
;
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Bifunctional 9, 3, 17, and trifunctional 20 dienophiles have been subjected to Diels-Alder reactions with 4H-pyrazoles 8 or 14 with inverse electron demand to form monoadducts 13, 15, 18, and 21 and bisadducts 16, 19, and 26. Acid-catalyzed reactions at 20°C occur according to 14 + 3 → 15 + 16 and 14 + 17 → 18 + 19. By contrast, the solution of barrelene (20) and 8 has to be subjected to 10 kbar and 130°C to give monoadduct 21 and bisadduct 26, In daylight 21 undergoes [2 + 2] cycloaddition to 27. The norbornene derivative 10 reacts with cyclopentadiene to form 13 which is obtained in higher yield by reaction of 10 with hexachlorocyclopenta-diene and subsequent reductive dehalogenation of adduct 12. X-ray analyses of 11 and 13 reveal only small differences in the structural parameters.
Additional Material:
1 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jlac.199519950244
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