Cyclotrimerization of butadiene

Scheme 5.2-24 Biphasic, Fe-catalyzed cyclotrimerization of butadiene in [BMIM][BF4],...

A number of compounds with this ring system (163), including dispiro derivatives, are formed by the catalytic cooligomerization of ketazines or aldazines with butadiene (Scheme 186)249 reactions of this type are analogous to the catalytic cyclotrimerization of butadiene to cyclodecatriene.250... 

Controlling Factors in Homo neous Tiansistion-Metal Catalysis Table 2.3-1. Cyclotrimerization of butadiene by means of Ni-, Ct- or Ti-catalysts ... 

In Scheme 2.3-3 some examples of the influence of DO/ACC-perturbations in and at the catalytically reacting tr-systems are given. It reveals the influence of CH3-or other alkyl-groups af the tr-system and that of the nitrogen atoms in the rr-system for the Ni-catalyzed 2 1 co-cyclotrimerization of butadiene with these substrates. 

The formation of CDT is suppressed if ethylene as well as butadiene is brought into contact with a naked-nickel catalyst. Depending on the reaction conditions, the product is a mixture of m,tram-1,5-cyclodecadiene (CDD) and 1,tram-4,9-decatriene (DT) (90). With equal concentration of butadiene and ethylene the co-oligomerization occurs some six times faster than the cyclotrimerization of butadiene to CDT. 

The dimerization and cyclotrimerization of butadiene are also catalyzed by titanium but are less well investigated. The Tiw Tj -octadienyl complex (22-XXXV) is isolable it catalyzes the dimerization of butadiene to the thermodynamically favored product, vinylcyclohexene.134... 

Cyclodimerization and Cyclotrimerization of Butadiene 371 Table 2. The cyclodimerization of butadiene. 

After the pioneering work of Inoue et al. [7] and Musco [5], the most detailed study of the cyclotrimerization of butadiene and CO2 has been carried out by Behr using catalysts formed in situ from Pd(acac)2 (acac = acetylacetonate) and three equivalents of a suitable phosphine ligand [4]. 

In the reaction of Ni(0)-phosphine complexes with butadiene Cg allyl complexes are formed, whereas Cjj allyl complexes are the products in the absence of phosphines. The Ni-catalyzed cyclotrimerization of butadiene to cyclododecatriene can be made to produce 1,5-cyclooctadiene, vinylcyclohexene or divinylcyclobutane instead by addition of phosphines . 

Bis(rv -trans oriented r -anti aUylic groups have been confirmed by NMR as intermediates of the stoichiometric cyclotrimerization of butadiene [6b,26b], and are also computationally predicted to be the thermodynamically favorable dodecatrienediyl-Ni" species. These stereoisomers are calculated to be 1.7 kcal mol lower in free energy relative to the stereoisomer 11 depicted in Scheme 4 [4c,d]... 

Nickel(0) supported on linear polyvinylpyridine exhibits catalytic activity and selectivity during cyclotrimerization of butadiene [89] ... 

Figure 2 9 Cyclotrimerization of butadiene (S) to 1, 5, 9-cyclododecatriene (CDT). The multiplicity of Ni-carbon bonds is shown by the superscripts on rj- Cg and C12 show the lengths of carbon chains.

As illustrated in the early achievements from Reppe on the cyclotetramerization of acetylene and from Wilke on the cyclodimerization and cyclotrimerization of butadienes, nickel-catalyzed cycloadditions possess considerable potential in the construction of medium ring systems. Pioneering studies by Wender have demonstrated many practical implications that have advanced the... 

Nickel(O) complexes also catalyze a variety of cyclooligomerizations of butadiene. Hiis process, studied intensively by Wilke and Jolly and co-workers, can lead to a myriad of products that depend on the reaction conditions (Scheme 22.22). The cyclotrimerization of butadiene to cyclododecatriene was one of the first organometaUic reactions subjected to careful mechanistic studies, and these studies led to the proposal that tiiis process occurs by the mechanism shown in Scheme 22.23. Again, the bis-ri -allyl complex containing 12 carbon atoms was isolated and characterized. It has been shown to enter the catalytic cycle as shown. 

Considerable work has also been devoted to catalytic properties of aromatic titanium-aluminumhalide complexes (CXL). These complexes have been reported to promote polymerization of ethylenes (Martin and Vohwinkel, 1961 Zimmer, 1966) and cyclotrimerization of butadienes (Vohwinkel, 1964) and isoprenes (Zakharkin and Akhmedov, 1969). They are able to lead to linear or cyclic polymers depending on the experimental conditions. For example, when butadiene is bubbled through a solution of CgHgTiCljAljCls in benzene, a vigorous reaction occurs. The yields of 1,5,9-cyclododecatriene (CDT), at the optimum temperature (60°-75°), are in the region of 60-65%. 

Extracts carboxylic acids from aq. solns. Widely used as a metal extractant, particularly for rare earth metals, and in the chromatography of these. Employed in catalysts for the cyclotrimerization of butadiene and for the cross-linking of epoxy resins. Cryst. (cyclohexane). Sol. cyclohexanone (35.6g per 100 cm 25°), common org. solvs. Mp 49-50°, Mp 59.5-60.0°. Bp, 225-228°. p/, 8.80 (MeN02). 

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