ISSN:
0009-2940
Schlagwort(e):
Benzylidene complexes
;
Vinylcyclopropane complexes
;
Vinylcyclopropanes
;
Cyclopropanation
;
Chemistry
;
Inorganic Chemistry
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
Vinylcyclopropane Complexes and Vinylcyclopropanes from Benzylidene Complexes and 1,3-DienesBenzylidenepentacarbonyl complexes (CO)5M[C(C6H4R-p)H] (1) [M - W:R=H (a), OMe (b); M=Cr: R - H (c), OMe (d)], react with cyclopentadiene by stereospecific transfer of the benzylidene ligand to one C=C bond of the diene and coordination of the resulting endo;-6-arylbicyclo[3.1.0]hex-2-ene (4) to the metal. The [CO]5M fragment occupies the exo-position. Addition of bromide liberates 4 from the metal. The reaction of 1a with 1,3-cyclohexadiene gives the corresponding (endo;-7-phenylbicyclo[4.1.0]hept-2-ene)tungsten complex (6) and, after addition of Br-, the free bicyclic compound. The sequential reaction of 1a with 1,2,3,4,5-pentamethylcyclopentadiene and Br- affords the endo;-6-phenyl-exo;-4-methyl isomer of pentamethylphenylbicyclo[3.1.0]hex-2-ene 9 with more than 85% stereoselectivity. The benzylidene transfer from 1a to cis-and trans-pentadiene, isoprene, and 2-chloro-1,3-butadiene proceeds regiospecifically to the more electron-rich C—C bond to give (E)- and (Z)-phenylvinylcyclopropanes. The E/Z ratio ranges from 0.52 to 2.2. The structures of the complexes 3d and 6 were established by X-ray analyses.
Zusätzliches Material:
2 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/cber.19911240503
Permalink
