ISSN:
0009-2940
Schlagwort(e):
Cyclopentadienes, synthesis of
;
[3 + 2] Cycloadditions of 1-metalla-1,3-dienes and alkynes
;
1-Metalla-1,3,5-trienes of tungsten, cyclization to cyclopentadiene complexes
;
η1-Cyclopentadiene tungsten complexes
;
Aminocarbene complexes of chromium and tungsten
;
Chemistry
;
Inorganic Chemistry
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
Organic Syntheses via Transition Metal Complexes, 54. - Cyclopentadienes from 1-Metalla-1,3-dienes and Alkynes by Cyclization of Intermediate 1-Metalla-1,3,5-trienes (Metal = Tungsten)We report on first examples of the formation of cyclopentadienes from a 1-metalla-1,3-diene LnM=C-C=C [LnM = W(CO)5] and an alkyne in [3 + 2] cycloaddition multistep reactions. In a first step the alkyne Et2N-C=C-Me (2) adds to the 1-metalla-1,3-diene (CO)5W = C(OEt)-CH=CHPh (1b) to give 1-metalla-1,3,5-trienes (CO)5W=C(NEt2)-CMe=C(OEt)-CH=CHPh (3b) and (CO)5W=C(OEt)-CH=C(NEt2)-CMe=CHPh (4b). In a second step 3b cyclizes to thecyclopentadiene complex 5, which has an η1 ylide-type structure as established by an X-ray analysis. Hydrolysis of 5 leads to the formation of a 3-aminocyclopentenone 7. The 1-metalla-1,3,5-triene 4b yields a cyclopentadiene complex 8. In contrast to 5 the carbon skeleton of 8 has a connectivity different from that of the C3 unit of the 1-metalla-1,3-diene 1.
Zusätzliches Material:
1 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/cber.19911241030
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