Transition metal-catalyzed double C_vinyl–H bond activation: synthesis of conjugated dienes

Abstract

Conjugated dienes occupied a pivotal position in the field of synthetic organic chemistry and medicinal chemistry. They act as important synthons for the synthesis of various biologically important molecules and...

Selective Palladium(II)‐Catalyzed Dimerization of Styrenes and Acrylates in Molten Tetrabutylammonium Acetate as an Ionic Liquid

“…Regarding the palladium source, in agreement with the literature, [3] palladium halides lead to modest conversions (Table 3, runs 8-9), as well as palladium in the zero-oxidation state (table 3, run 10). In this regard, it was observed that starting with Pd(0), the conversions in the first hour of the reaction are very low, suggesting the need for an induction time required for the oxidation of palladium before it can be catalytically active.…”

“…The oxidation or acetoxylation of the olefin, as well as its non‐oxidative dimerization, are competitive processes, and in the presence of arenes, the olefin can be also arylated. Reactions are usually carried out in a polar solvent such as water or acetic acid, but also classic organic solvents and both homogeneous and heterogeneous palladium catalysts (recently also other metals) are known [1–3,7,8,12,14,15] …”

“…[2,3] Given their importance, the synthesis of 1,3-dienes by coupling two vinyl fragments has attracted the attention of many research groups from the 1960 s [4][5][6] to the present. [1,3,[7][8][9] As an example, the oxidative dimerization of styrene to 1,4diphenyl-1,3-butadiene (also called oxidative coupling, OCS) promoted by palladium acetate is a well-known method in organic synthesis, [4,6,10] widely studied due to the importance of the diaryl conjugated dienes in the field of material science. [11,12] Several olefins substituted at the double bond like 1methylstyrene, 1-1-diphenylethylene, vinyl acetate, etc., undergo this reaction.…”

Carbon-Centered Radical with Leaving Group-Mediated Ring Opening of Cyclopropenes via the Rearrangement of Cyclopropyl to the Allyl Radical: A General Access to Multisubstituted 1,3-Dienes

“…In addition, these structural motifs also play important roles in organic synthesis − and materials science, − such as synthetic intermediates and chelating ligands. Accordingly, considerable efforts have been devoted to developing effective catalytic approaches − for the synthesis of such class of compounds, especially stereoselective ones − due to the importance of geometry that eventually affects the function. However, while straightforward synthetic strategies now exist for the synthesis of simple 1,3-diene derivatives, − acquiring multisubstituted conjugated dienes with readily available starting materials remains a challenge.…”

Phenol-mediated decarboxylative proton transfer of γ-methylidene-δ-valerolactones: an approach towards (E)-2,4-pentadienoates

“…Elimination reactions 8 a and olefination reactions 8 b have been widely employed, but they are frequently associated with the problems of uncontrolled generation of E and Z isomers, which need rigorous purification. In the past decades, to realize the stereoselective synthesis of substituted 1,3-dienes, a variety of strategies have been developed, 9 including vinyl C–H bond activation, 9 d cross-coupling reactions, 10 ene-yne metathesis, 11 functionalization of alkynes 12 or 1,3-diynes, 13 isomerization, 14 Kumada vinylation 15 and aerobic dehydrogenation. 16 Despite the effectiveness of the aforementioned methods, developing a direct, highly stereoselective approach towards the synthesis of polysubstituted 1,3-conjugated dienes remains elusive and is highly desirable.…”