Dicyclopentadienylzirconium

Jordan RF, Bajgur CS, Dasher WE, Rheingold AL (1987) Hydrogenation of cationic dicyclopentadienylzirconium(IV) alkyl complexes. Characterization of cationic zirconium(IV) hydrides. Organometallics 6 1041-1051... 

The combination of dicyclopentadienylzirconium dichloride and silver perchlorate activates armed glycosyl sulfoxides in dichloromethane between -20 °C and room temperature, but only very simple acceptors were studied [335]. Other Lewis and Bronsted acids studied include the environmentally benign europium, lanthanum and ytterbium triflates [336], certain polyoxometallates [337], sulfated zirconia [338] and Nafion H [338]. 

Aluminoxanes suppressed side reactions involving hydrogen transfer. They also formed cyclic structures with starch, giving copolymers that were coated with crystalline polyethylene. A catalyst composed of dicyclopentadienylzirconium dichloride and trimethylaluminium permitted polymerization of ethylene on starch in a toluene suspension at 60 °C for 2h.2806 Graft copolymerization of methyl methacrylate onto starch was also performed with an acetylacetone-copper(II) complex in trichloroacetic acid.2807 The grafting yield and efficiency were proportional to the initiator concentration up to 7.0 x 10-3 mole/L. 

In a similar manner, 1,7-octadiene and 1,6-heptadiene can be reductively cyclized to give, after acidic workup of the resulting carbometalation product (see Section 1.5.8.4.4,), cisjtrans mixtures of 1,2-dimethylcyclohexane and 1,2-dimethylcyclopentane, respectively, with opposite preference of the diastereomersls. The reaction uses 1.5-fold equimolar amounts of dibutyl-magnesium and is catalyzed by dicyclopentadienylzirconium dichloride. If oxidative workup is used instead of hydrolysis, the corresponding diols are obtained15. Several other examples of this type have been reported82. 

Scheme 6.9. Rationale for the ul selectivity of dicyclopentadienylzirconium ester enolates in [2,3]-Wittig rearrangements.

In 1986 [63], Katsuki showed that the dicyclopentadienylzirconium ester enolates shown in Scheme 6.13 afforded products where three stereochemical elements in the product were controlled with a high degree of selectivity the double bond geometry, the relative configuration, and the absolute configuration. Only one double bond isomer was observed, the syn/anti diastereoselectivity was 98-99%, and the enantioselectivity was >98%. 

Dicyclopentadienylzirconium dichloride. See Zirconocene dichloride Dicyclopentenyl acetate (5-ene isomer). See Greenyl acetate... 

Zirconium turnings. See Zirconium Zirconocene dichloride CAS 1291-32-3 EINECS/ELINCS 215-066-8 Synonyms Dicyclopentadienylzirconium dichloride Zirconium, dichloro-di-pi-cyclopentadienyl-... 

C3oH3oNi 6 f Hexakis[(r -cyclopentadienyl)nickel](12Ni-Ni), 46B, 906 C3oH3o03Zr CyHg, Tri-M oxo-tris(dicyclopentadienylzirconium) toluene solvate, 45B, 991... 

A high yield synthesis of zirconoles from alkyl(hydrido)zirconium(iv) species and alkynes has been reported. The suggested mechanism for the reaction, shown in Scheme 5, involves RH elimination rather than initial insertion via an alkyl-(alkenyl)dicyclopentadienylzirconium intermediate. ... 

The coupling of allylic chlorides with trimethylsilylalkynes in the presence of [PdCl2(PhCN)a] also exhibits good regio- and stereo-selective control to give 4-trimethylsilyl-5-chloro-l,4( )-dienes. Furthermore, upon treatment with fluoride, these produce the corresponding 1,4-enynes. Dicyclopentadienylzirconium diene complexes are readily carbonylated, and the adducts, after hydrolysis with acid, afford cyclopent-3-enones, sometimes in synthetically useful yields. ... 

An (Ti2-phosphabenzyne)dicyclopentadienylzirconium-trimethylphosphine adduct, (50), was obtained323 by thermal loss of RH from a [Cp2Zr(R)-2-substituted phosphinine (R = Me, Ph) in the presence of trimethylphosphine. It was reported that CSC and C=0 multiple bonds selectively inserted into into the -C2(ring) bond of this system. 

Hydrozirconation of olefins can be readily accomplished by the use of the hydride XLIV derived from the relatively inexpensive reagent, dicyclopentadienylzirconium dichloride (Hart and Schwartz, 1974). Very... 

---