ISSN:
0009-2940
Schlagwort(e):
Butadiene dianion equivalent, 1,4-addition
;
Metallocene template, bent
;
Enamine, primary, stable
;
Metallacycles, nine-membered, chiral
;
Zirconocene
;
Chemistry
;
Inorganic Chemistry
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
(η4-Butadiene)zirconocene adds one equivalent of benzonitrile to form the five-membered azazirconacyclopentene derivative 7, which contains an NH group in the ring and a vinyl substituent at the α-carbon center. The reaction of 7 with an additional equivalent of benzonitrile furnishes the chiral nine-membered metallacycle () (12) which may be isomerized to the thermo-dynamically favored tautomer () (13). The Gibbs activation energy of the enantiomerization of the trans-cycloalkene-like 13 is ΔG#(323 K) = 15.5 ± 0.3 kcal mol-1. The analogous conformational equilibration of 12 has a lower activation barrier of ΔG# (236 K) = 12.1 ± 0.3 kcal mol-1; complex 13 is characterized by X-ray diffraction. Hydrolysis of 13 yields the conjugated 1,6-diamino-1,6-diphenylhexatriene 16 which is characterized by X-ray diffraction.
Zusätzliches Material:
2 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/cber.19921250724
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