Palladium-catalyzed coupling Heck reaction

Both decks of the [2.2]paracyclophane derivatives 160 and 161 could be transformed into 1,4-distyrylbenzene chromophores via the palladium-catalyzed coupling (Heck reaction) with styrene and substituted styrenes adopting the protocol of Jeffery [106]. The fourfold coupling products 162 and 163 were thus obtained with yields up to 70% [107a]. As four new carbon-carbon bonds are formed in this transformation, each single coupling step must proceed with excellent yield. All these reactions lead stereoselectively to products with (E)-configurated double bonds. 

In 2011, Palladium-Catalyzed Oxidation Heck Reactions, by Su and Jiao [102]. Recent Advances in Sonogashira Reactions, by Chinchilla and Najera [112]. Nanocatalysts for Suzuki Cross-Coupling reactions, by Fihri, Bouhrara, Nekoueishahraki, Basset, and Polshettiwar [113]... 

Szlosek-Pinaud et al. developed a very simple and efficient method for the preparation of a wide range of functionalized 3,3-disubstituted-2,3-dihydrobenzofurans 64 via palladium-catalyzed tandem Heck reaction/Suzuki cross-coupling [24] (Scheme 6.15). 

Palladium-catalyzed coupling reactions of organic halides with olefins or dienes (R. F. Heck, 1979) are broad in scope and simple to carry out. Anhydrous conditions or any special technique are not required and most functional groups are tolerated. 

Due to their successful synthesis of 2-(4 -chlorophenyl)-4-iodoquinoline from the corresponding precursor acetylene, Arcadi et al. (99T13233) developed a one-step synthesis of 2,4-disubstituted quinolines via palladium-catalyzed coupling reactions. An example is the Heck reaction of 4-iodoquinoline (131) with a-acetamidoacrylate (132). This one-pot synthesis yielded adduct 133 in 50% overall yield after purification via flash chromatography. 

The Heck coupling reaction appeared to be a route of choice to achieve the synthesis of the modified-DIOP ligands. We previously studied the palladium-catalyzed coupling of acrolein and acrolein acetals with several polyaromatic and heteroaromatic bromides either in the presence of homogeneous or heterogeneous catalytic systems (6, 7). After optimization of the reaction conditions, high conversions and selectivities were achieved except with anthracenyl derivatives (8). Based on these results, we developed the synthesis of the desired ligands. The... 

Diazonium salts react with various nucleophiles in water (Eq. 11.62).106 In acidic aqueous solution, p-pheny I e ncbis di azo ni um ion reacts with alcohols more rapidly than it does with water.107 In the presence of nucelophiles such as halides, the substitution products are obtained. Furthermore, diazonium salts of aromatic compounds are excellent substrates for palladium-catalyzed coupling reactions such as the Heck-type reactions in water. 

In the second series of experiments, O. Nuyken et al. investigated the Heck reaction of iodobenzene with styrene as a model for the numerous palladium-catalyzed coupling reactions (Scheme 6.6) [54]. In the literature only a few Heck coupling reactions of hydrophobic substrates in aqueous solution are known. The most detailed study has been performed by Jeffery et al. on the model reaction of iodobenzene with methylacrylate in the presence of tetrabutylammonia salts. Product yield was at least 95% after 2 h reaction time at 50 °C in pure aqueous solution [55], however more... 

Palladium-catalyzed coupling of organostannanes, 50, 1 Palladium intermediates in Heck reactions, 60, 2... 

Palladium-catalyzed coupling reactions of the Heck type have in many instances involved indole and pyrrole derivatives. Although the mechanisms are complex, organopalladium species are implicated (84H(22)1493). Vinylation of A-substituted-3 -iodoindoles with amidoacrylate groups provides a useful functionalization of indoles (Scheme 81) (90JOM(39l)C23). Yields are improved in intramolecular reactions, e.g. (406 — 407) and (408 — 409) <92H(34)219,91CPB2830). 

Palladium-catalyzed coupling reactions have important synthetic applications (210—212). The prototypical reaction is the Heck reaction (213) whereby an organoPd(II) undergoes coupling with an olefin (eq. 11). 

Palladium-catalyzed olefin arylation reactions ( Heck coupling ) have been successfully employed for the generation of C-C bonds in organic synthesis for decades [174-177]. Arylhalides and olefins are coupled by palladium catalysts (typically with phosphine co-ligands) in the presence of base, such as a tri-alkylamine. 

Similar to alkenyliodonium salts (see Sect. 6.3), aryliodonium salts are highly reactive substrates in Heck-type olefination and other palladium-catalyzed coupling reactions. Aryliodonium salts can serve as very efficient reagents in the palladium-catalyzed arylations of acrylic acid 101 [75], organotin compounds 102 [76], sodium tetraphenylborate 103 [77], and copper acetylide 104 [78] (Scheme 45). 

The useful and selective reactivity of arylboronic acids makes them favorite building blocks for many modern organic chemistry applications. Arylboronic acids also serve as highly useful arylpalladium precursors in palladium(II)-catalyzed oxidative Heck reactions. Andappan et al. developed a microwave-accelerated protocol for oxidative Heck couplings using cop-per(II) acetate as the palladium reoxidant [52]. The method proved to be... 

With such benefits offered by silver salts in these Heck-type reactions, chemists looked for similar improvements in other palladium-catalyzed couplings and related reactions. 

Brase, S. and de Meijre, A., Palladium-catalyzed Coupling of Organyl Halides to Alkenes - the Heck Reaction , in Metal-catalyzed Cross-coupling Reactions, Wiley-VCH, Weinheim, 1998, pp. 99-166. 

S. Brase and A. de Meijere, Palladium-Catalyzed Coupling of Organyl Halides to Alkenes—The Heck Reaction, in Metal-Catalyzed Cross-Coupling Reactions, (F. Diederich, P. J. Stang, Eds.), Wiley-VCH, Weinheim, 1998, 99-154. 

The Heck reaction is the palladium-catalyzed coupling of an aryl or vinyl halide with an alkene to give a new C—C bond at the less substituted end of the alkene, usually with trans stereochemistry. 

Triflates of 3-benzo[. ]furans were prepared, and evaluated in the palladium-catalyzed Stille, Heck, Suzuki, and Sonogashira coupling reactions. As can be seen in Scheme 55, results demonstrated that benzo[. ]furan-3-triflate 109 was a good coupling partner in the metal-catalyzed reactions, and good to excellent results were obtained <2002SL501>. 

For organic synthesis applications, C-C bond formation between the R group and an alkene carbon atom is of paramount importance and Pd-catalyzed R-R coupling is to be avoided. Equation (5) displays a palladium-catalyzed Mizorki-Heck-type (MH) reaction using tellurium salts. ... 

The Heck reaction is a palladium-catalyzed coupling of a vinyl or aryl halide with an alkene to form a more highly substituted alkene with a new C-C bond. Palladium(II) acetate [Pd(OAc)2] in the presence of a triaiylphosphine [P(o-tolyl)3] is the typical catalyst, and the reaction is carried out in the presence of a base such as triethylamine. The Heck reaction is a substitution reaction in which one H atom of the alkene starting material is replaced by the R group of the vinyl or aryl halide. 

Heck reaction (Section 26.3) The palladium-catalyzed coupling of a vinyl or aryl halide with an alkene to form a more highly substituted alkene with a new carbon-carbon bond. 

Figure 3-2 Some biologically active compounds prepared by application of Heck reactions with asymmetric induction. (The dashed lines indicate bonds formed by palladium-catalyzed coupling).

Palladium-catalyzed Coupling of Oi anyl Halides to Alkenes - The Heck Reaction... 

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