ISSN:
0021-8383
Schlagwort(e):
Chemistry
;
Organic Chemistry
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
The Reaction of E-ß-Nitro-styrenes with 3-Pyrazolidone-azomethinimines - a Non-cisoid 1,3-Dipolar CycloadditionNormal flipping at both ring-N-atoms postulated, the thermal addition of E-β-nitro-5a or E-(4-chloro-β-nitro)-styrene 5b to 3-pyrazolidone-azomethinimine-1,3-dipoles 4a or 4b formally can yield 8 isomeric pairs of enantiomers, 4 of which are “permitted”(cisoid) and 4 of which are “forbidden” according to the concerted [π4s + π2s]-mechanism. If the addition of 5 to 4 is regiospecific, 2 “permitted”(cisoid) (1 and 6) and 2 “forbidden”(3 and 10) isomers are conceivable. From pure 5a and 4a we regiospecifically got 1ref,3trans-diphenyl-2cis-nitro-6a (75%) and 1ref,3trans-diphenyl-2trans-nitro-5-oxo-perhydropyrazolo[1,2-a]pyrazol 10a (25%), from 5b and 4b the corresponding bis(4-chloro-phenyl)-isomers 6b and 10b. The sodium salts 8a, b, gained from 6a, b and 10a, b, are identical. With H⊕ (D⊕) in water (D2O) 8a, b give 6a, b (2-deutero-6a, b = 7a, b). The 1H-n.m.r. spectra of 6a, b, 7a, b, 8a, b, 10a, b, and of the 2-amino-isomers 11a/12a, corresponding to 6a/10a, are discussed.For the first time products of a non-cisoid 1,3-dipolar cycloaddition (10a, b) were isolated. In the discussion (E ⇌ Z)-isomerization of 5a, and conceivable mechanisms of isomerizations 6a → 10a are excluded. Theoretical consequences are suggested.
Zusätzliches Material:
2 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/prac.19793210407
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