Cyclooligomerization of 1,3-dienes

The catalytic cyclo-oligomerization of 1,3-butadiene mediated by transition-metal complexes is one of the key reactions in homogeneous catalysis.1 Several transition metal complexes and Ziegler-Natta catalyst systems have been established that actively catalyze the stereoselective cyclooligomerization of 1,3-dienes.2 Nickel complexes, in particular, have been demonstrated to be the most versatile catalysts.3... 

As mentioned above, many transition metals catalyze the cyclooligomerization of 1,3-dienes. The nickel-catalyzed cyclooligomerization of BD, however, is probably one of the best-understood reactions in the field of homogeneous catalysis. In the 40 years since its discovery a mass of evidence has been collected, indicating that these oligomerizations are the result of a multistep addition-elimination mechanism at a nickel atom template, which constantly flips between two oxidation states. The following strategies played an important role isolation of key intermediates, simulation of the catalytic cycle in a stoichiometric manner, product analysis, and study of model compounds. Detailed analysis of the intellectual development of the mechanism is not included here as this can be followed from excellent reviews [6]. 

Abstract The transition-metal-catalyzed cyclooligomerization of 1,3-dienes and the cooligomerization of 1,3-dienes and alkenes, that involve the stereoselective formation of carbon-carbon bonds, are of great interest from both a scientific as well as an industrial point of view. In this account a theoretical well founded, comprehensive mechanistic view of the [Ni ]-catalyzed co-oUgomerization of 1,3-butadiene and ethylene is presented. The... 

This leads us to propose a theoretically verified, refined catalytic cycle for production of linear and cycHc CiQ-olefin products (cf. Scheme 3). Furthermore, a detailed comparison of crucial mechanistic aspects of the catalytic reaction course for co-oligomerization of butadiene and ethylene and for cyclooligomerization of butadiene promoted by zerovalent bare nickel complexes was undertaken. These contribute (first) to a more detailed understan(fing of mechanistic aspects of the [Ni"]-mediated co-oHgomerization of 1,3-dienes and olefins and (second) to a deeper insight into the catalytic structure reactivity relationships in the transition-metal-assisted co-oHgomerization and oligomerization reactions of 1,3-dienes. 

Cyclooligomerization. Ever since the first cyclodimerization reaction of 1,3-butadiene to yield 1,5-cycloctadiene catalyzed by a so-called Reppe catalyst was reported45 [Eq. (13.12)], cyclooligomerization of conjugated dienes has been intensively studied ... 

It is appropriate to include here two bis(T)3-allyl)nickel complexes that are formed by reacting zerovalent nickel species with 1,3-dienes and that have been shown to be involved as intermediates in the nickel-catalyzed cyclooligomerization of butadiene, viz., (T)3,i73-C12H18)Ni and (rj3-QH NiPRa. 

The first catalytic cyclodimerization of 1,3-butadiene (BD) to 1,5-cycloocta-diene using modified Reppe catalysts was reported by Reed in 1954 [4], and only two years later Wilke reported on the titanium-catalyzed synthesis of cyclo-dodecatrienes from BD [5]. It remained for Wilke and his co-workers to show the tremendous versatility and scope of the nickel-catalyzed cyclooligomerizations of... 

The cyclooligomerization reaction is not confined to BD as the monomer. Activated or monosubstituted 1,3-dienes also react, but reaction rates are usually slow, and selectivity and turnover numbers (TONs) are low. Cyclotrimerization and cyclodimerization of substituted 1,3-dienes - either alone or in admixture with BD - give numerous isomers of substituted CDT, COD, VCH and divinyl-cyclobutane (DVCB). For example, isoprene [34], 1,3-pentadiene [35], 2,3-dimethylbutadiene [36], 1,3-hexadiene [37], and even 1-vinyl-1-cyclopentene [38] do react (eqs. (2)-(6)). 2,4-Hexadiene is inert. 

Photolysis of 2-(2 -cyclopropylcyclopropyl)cycloalkanones (108 n = 1, 2) gave ring-expanded products e.g. (108 n = 1) gave a mixture of cyclododecanone (61 %) and 2-cyclopropylcyclononanone (20%). Ring expansion of cyclic mono- and diacetylenes by 4, 8 or 12 carbon atoms can be achieved by nickel-catalysed cyclooligomerization with buta-1,3-diene, followed by oxidative cleavage thus cyclo-tetradec-l,8-diyne was converted into cyclotriacontane. ... 

---