Alkenes cyclooligomerization

A couple of prototypical examples of the cyclic version of the Heck reaction, defined as a process consisting of alkene carbopalladation followed by -elimination, were reported during the 1984-1985 period [9,10]. Almost concurrently, seminal examples of both the non-Heck cyclic carbopallation reactions [10,30] were reported during the 1983-1985 period. Thus, with due respect paid to earlier discoveries of alkyne cyclooligomerization via cascade carbopalladation [7,8] as well as copolymerization [24] and cocyclization [25,... 

In the case of reactions such as valence isomerization, metathesis reactions of alkenes and alkynes, oligomerization or cyclooligomerization of olefins, metallacycloalkanes are of special importance. Their catalytic efficiency depends on the ease of the M—C bond cleavage, which is the result of reductive elimination of the organic substrate or of /J-hydrogen transfer. Also a- or / -C—C bond rupture has been reported. Heterocycles with an aliphatic carbon skeleton and a donor atom adjacent to the metal are suitable model compounds for the study of individual catalytic steps and structural properties. In connection with the activation of C—H bonds, cyclometa-lation has become a very general reaction and was reviewed in 1977. ... 

Cyclocodimerization and cyclooligomerization reactions of cyclopropenes catalyzed by nickel complexes require alkenes with electron-withdrawing substituents as reaction partners. In this respect, these reactions are complementary to the copper-catalyzed additions discussed in the previous section which do not proceed with electron-poor alkenes due to the low nucleophilicity of the copper-carbene complex. 

Similar to cyclodimerizations, transition metal catalyzed cyclooligomerizations and cocyclooligomerizations involve dicarborative addition steps. The most important examples of this type are represented by cyclotrimerization and cyclotetramerization of alkenes. dienes, alkynes and systems with hetero multiple bonds, leading to carbocyclic and heterocyclic six-, eight- or twelve-membered rings1 ... 

Applications of transition metal catalyzed cyclooligomerizations and cocyclooligomerizations to stereoselective synthesis are restricted to some special methods, such as cyclotrimerizations and cocyclotrimerizations of alkenes and alkynes ([2 + 2 + 2] cyclooligomerizations), as well as homo-Diels-Alder reactions of norbornadiene (formal [2 -b 2 + 2] cyclooligomerizations). 

Cyclopentanones, Cyclopentenones and Cyclopentadienones via Carbonylative [2 + 2 + 1 Cyclooligomerization of Alkenes and Alkynes with Carbon Monoxide... 

Review W. Reim, A. Behr, M. Roper, Alkene and alkyne oligomerization, cyclooligomerization and telomerization reactions, in Comprehensive Organometallic Chemistry, (Eds. G. Wilkinson, F. G. A. Stone, E. W. Abel), I rgamon, Oxford, 1984. 

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... 

Polymerization Reactions (Including Cyclooligomerization) of Alkenes and Alkynes Using Polymeric Transition Metal Catalysts... 

The formal cyclooligomerization of vinylidene units via copper or nickel car-benoids represents another route to [4]radialenes. To this end, a l,l-dibromo(or chloro)-alkene can be converted into a bis(l-halogenovinyl)cuprate at low temperatures, which, on warming, furnishes the [4]radialene, often accompanied by the corresponding dimerization product, the [3]cumulene. This method is so far the only route to octaphenyl[4]radialene (see Scheme 4.10, Section 4.2.1) and other octaaryl[4]radialenes [10, 37]. With l,l-dibromo-2-methylprop-l-ene (32) as the starting material, a mixture of [4]radialene 71 and [Sjradialene 84 as the major products is formed [76] (Scheme 4.17). While this method is not the preferred route to the former radialene, it represents the only known way for the preparation of 84. Treatment of dibromoalkene 32 with a Ni(0) complex [37] or activated nickel [10] does not improve the yield of radialene 71. 

---