Via Pd-Catalyzed Coupling

Scheme 20.10 Synthesis of benzannulated enyne-allenes via Pd-catalyzed couplings.

Scheme 19. Synthesis of nzatriptan (4) via Pd-catalyzed coupling of an iodoaniline and an alkyne.

Kok, S. H. L. Shing, T. K. M. A new synthetic approach towards N-alkylated 2-epi-valiena-mines via Pd-catalyzed coupling reaction. Tetrahedron Lett. 2000, 41, 6865—6868. 

Barbarella, G. Zambianchi, M. Polyhydroxyl oligofhiophenes. I. Regioselective synthesis of 3,4 - and 3,3 -di(2-hydroxyefhyl)-2,2 -bifhio-phene via Pd catalyzed coupling of fhienyl-stannanes with thienyl bromides. Tetrahedron 1994, 50,11249-11256. 

A type Ilae reaction has been reported by Willis and co-workers who prepared N-substituted indoles via Pd-catalyzed coupling of 2-(2-haloalkenyl)-aryl halides with a variety of amines <06ASC851>. In an alternative intermolecular approach to ring construction, Tang and Hu have reported a Pd-catalyzed coupling of o-alkynylhalobenzenes with amines to afford 1,2-disubstituted indoles <06ASC846>. 

A one-pot tandem process for the synthesis of (E j-enediynes that allows incorporation of ethynyl groups is via Pd-catalyzed coupling of ( j-bromoiodoethylene with zinc alkynylides. " " ... 

Due to their successful synthesis of 2-(4 -chlorophenyl)-4-iodoquinoline from the corresponding precursor acetylene, Arcadi and group [65] developed a one-step synthesis of 2,4-disubstituted quinolines via Pd-catalyzed coupling reactions. An example is the Heck reaction of 4-iodoquinoline 145 with oc-acetamidoacrylate 146. This one-pot synthesis yielded adduct 147 in 50% overall yield after purification via flash chromatography. 

Scheme 53. Synthesis of double-layered distyrylbenzene chromophors via Pd-catalyzed coupling reactions R = C02Me,C6H5)C6H4-4-C02Me,C6H4-4-0Me [107]...

One method for the a-iodination of ketones calls for the assistance of selenium dioxide. Heterocyclization. A new route to a-iodo boronic acids consists of iodoethe-rification. p-Iodobutenolides that are useful for carbon chain extension at the P-position (via Pd-catalyzed coupling) are readily accessible by iodolactonization of allenic acids ... 

Vanderzande et al. reported the facile synthesis to 5,6-disubstituted-l,3-dithienylbenzo[c]thiophenes 3.10 via Pd°-catalyzed coupling reaction of 5,6-dichloroterthiophenes 3.9 with an alkyl Grignard reagent (Scheme 1.30) [309, 321]. Chemical polymerization of the 5,6-modified monomers with FcCIb yielded polymers with bandgaps of 1.4-1.8 eV, which are similar to that of poly(dithienylbenzo[c]thiophene) P3.3 [309]. Application of these polymers as donors and fullerene PCBM as acceptor in bulk heterojunction solar cells (BHJSC) was also investigated and reported. An overall power conversion efficiency of 0.3 % and an internal power conversion efficiency of 24% were obtained for PMMA-poly-P3.9c-PCBM (1 2 6) blended devices [321]. 

The Stille reaction [41] is a general, selective, and multifaceted palladium-catalyzed reaction used to construct C—C bonds [42]. It proceeds via Pd-catalyzed coupling of organic electrophiles such as unsaturated halides, sulfonates, or triflates with functionalized organostannanes. Although it is nowadays considered a standard method in organic synthesis, recent modifications and variants of the Stille reaction have opened up a multitude of new and highly attractive synthetic possibilities. 

The oxypalladation-reductive elimination of 3-pentynoic acid with 1-bromo-l-heptyne has also been described (Scheme 22). However, 4-methyl-4-(l-heptynyl)-5//-furan-2-one was isolated in low yield. Substitution of 1-iodo-l-heptyne for 1-bromo-l-heptyne resulted in the formation of the diyne derivative as the only reaction product. Most probably, the diyne derivative is formed via Pd-catalyzed coupling of the l-halo-l-aUcyne. 

In 2009, a one-step protocol for the synthesis of xanthones via Pd-catalyzed coupling between 1,2-dibromoarenes and salicylaldehydes was developed. The success of the reaction relies heavily on the careful selection of a proper palladium catalyst, solvent and base moderate yields of the desired products were formed (Scheme 3.2). In this communication, a reaction mechanism was proposed by the authors. The Pd(0) catalyst first underwent oxidative insertion into one of the carbon-halide bonds to generate the aryl-Pd(ii) intermediate, which reacted with the phenolate to displace the halide, then underwent C-H activation of the C-H bond of the aldehyde to form intermediate A. After abstraction of the hydrogen atom by the base and reductive elimination to exclude the Pd(0) catalyst, the biaryl ketone intermediate was... 

M. Rehahn, A. D. Schluter, G. Wegner and W. J. Feast, Soluble Poly(/7ara-Phenylene)s. 2. Improved Synthesis of Poly(/jara-2,5-Di-Normal-Hexylphenylene) via Pd-Catalyzed Coupling of 4-Bromo-2,5-Di-Normal-Hexylbenzeneboronic Acid, Polymer, 1989,30(6), 1060-1062. 

The lamellarins are an important group of marine natural compounds having a pyrrole ring as a core component of their skeleton. Albericio and Alvarez have found a modular approach to these natural products 69 on soUd phase by assembling appropriate building blocks via Pd-catalyzed coupling reactions introducing three points of diversity (Scheme 10) [107]. 

Fig. 15 Synthesis of N-Arylated Porphryins via Pd-Catalyzed Coupling Reactions...

Improved synthesis of PPP with significantly greater DP was reported via Pd-catalyzed coupling of 4-bromo-2,5-disubstitutedbenzeneboronic acid (26) [37,38] according to the Suzuki and Miller methods (Scheme 10) [39,40]. 

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