Cyclooligomerization and Cycloisomerization of Alkenes and Alkynes

Abstract

Nickel-catalyzed cyclooligomerization and cycloisomerization reactions of alkenes and alkynes form the cornerstones of organic transition metal chemistry (Reppe, in the 1940s; see Section 6.3.1), and so far these have been among the main subjects studied extensively. In this chapter, nickel-catalyzed cyclooligomerization and cycloisomerization reactions will be described, as will certain nickel-mediated (stoichiometric) reactions, which are closely related to the catalytic reactions. Emphasis is placed on recent developments in nickel chemistry, as earlier studies have been repeatedly reviewed from several viewpoints [1-10]. Cyclization and cycloaddition reactions which involve the addition of other substrates (e.g., hydrosilanes, hydrostannanes and disilanes) will be described in other appropriate chapters in this monograph. 6.1 Cyclooligomerization of AlkenesIn nickel-catalyzed cyclooligomerization reactions of alkenes, strained compounds such as cyclopropenes, methylenecyclopropanes, and norbornadiene are normally used as the reactive substrates. The reactions may involve either the cleavage of the weakened carbon-carbon p bond -as is the case for many cyclooligomerization and cycloisomerization reactions -or the cleavage of the strained carbon-carbon s bond, which is followed by the formation of new carbon-carbon s bonds. Unstrained alkenes usually produce linear oligomers in the presence of nickel catalysts (see Chapter 3).Cyclopropenes are highly strained carbocyclic compounds. For example, the calculated strain energy of cyclopropene is 228 KJ mol À1 (54.5 Kcal mol À1 ) [10]. Accordingly, cyclopropenes are prone to undergo cyclooligomerization in the presence of a Ni catalyst. As an example, 3,3-dimethylcyclopropene provides cyclodimerization and cyclotrimerization products (Eq. (6.1)) [11a, b]. A generally accepted mechanism for this reaction is shown in Scheme 6.1, where the Ni(0) complex interacts with the p bond of the cyclopropene molecule and forms a Ni(0)-h 2 -olefin Modern Organonickel Chemistry. Edited by Y. Tamaru

Estimation of Kinetic Parameters and Simulation of Methylacetylene and Propadiene Liquid-Phase Selective Hydrogenation Reactor Considering the Catalyst Deactivation

“…Oligomer formation by cyclotrimerization reactions, cocyclotrimerization of alkynes and alkaldienes, has been extensively discussed. 23,24 In the given reports, a large number of cyclic and aromatic compounds such as BZ and TL can be formed during consecutive complex oligomerization reactions from BD, MA, and PD. The PR aromatization reactions with various catalysts are explained in some literature.…”

“…They have described that in the hydrogenation reaction of PD, the BZ product is formed from the cyclotrimerization of PD. Oligomer formation by cyclotrimerization reactions, cocyclotrimerization of alkynes and alkaldienes, has been extensively discussed. , In the given reports, a large number of cyclic and aromatic compounds such as BZ and TL can be formed during consecutive complex oligomerization reactions from BD, MA, and PD. The PR aromatization reactions with various catalysts are explained in some literature. , They have stated that PR can be converted to aromatic compounds such as BZ and TL during a catalytic aromatization reaction.…”

Nickel-Catalyzed Synthesis of Quinazolinediones

“…Nickel­(0)-catalyzed cycloadditions of unsaturated organic compounds comprise a large family of reactions that give access to unsaturated five- and six-membered rings . When one of the components is an isocyanate, these transformations allow access to a broad range of heterocycles including pyridones, pyrimidiones, , amides, imides, and hydantoins .…”