Palladium-catalyzed synthesis activation

Palladium-Catalyzed Synthesis of Vitamin D-Active Compounds... 

Sequential amination and C-H activation constitutes the key to a palladium-catalyzed synthesis of carbazoles, which enabled, for instance, efficient assembly of the compound 388 (Equation 111) <2002CC2310>. 

Cationic palladium-catalyzed addition of arylboronic acids to nitriles for the formation of benzo[h]furans was reported <06OL5987>, an example of which is illustrated in the following scheme. The palladium-catalyzed cross coupling of alkynes with appropriately substituted aryl iodides for the synthesis of substituted dibenzofurans in moderate to excellent yields was also achieved <06JOC5341>. The benzo[fc]furan core of heliannuls G and H were constructed by a palladium-catalyzed Ji-allyl cyclization reaction <06TL7353>. The palladium-catalyzed oxidative activation of arylcyclopropanes was applied to the synthesis of 2-substituted benzo[Z>]furans <06OL5829>. 

M.Catellani,E.MottiandS.Ghelli,IntramolecularbenzylicC-H.activation Palladium-catalyzed synthesis of hexahydromethano-fluorenes, Chem. Commun., (2000) 2003-2004. 

Scheme 3.20 Palladium-catalyzed synthesis of heteroq cles via C-H activation.

In 2012, a palladium-catalyzed ring opening of aminocyclopropyl Ugi adducts was presented. Dihydropyridine and benzoazepinone derivatives were produced in moderate yields (Scheme 3.35a). Catellani and co-workers reported a palladium-catalyzed synthesis of substituted phenanthridine derivatives in 2008. Selectively substituted phenanthridine derivatives were obtained by a facile reaction of o-allqrlated aiyl iodides, o-bromoar-enesulfonylanilines and activated olefins in the presence of palladium and norbornene as catalysts. The reaction takes place under mild conditions to give the products in satisfactory yields using readily available starting materials (Scheme 3.35b). 

SCHEME 2.70 Palladium-catalyzed synthesis of heterocycles through C—H activation [97]. 

SCHEME 4.206 Palladium-catalyzed synthesis of arylphosphine oxides through C—H activation [342]. 

Palladium-catalyzed synthesis of oxygen-containing heterocycles involving a C-H activation/C-C formation process has been substantially investigated in the past few decades. Palladium-catalyzed arylation, olefination, alkylation. 

Based on the rapid development of C-H activation in the past few decades, palladium-catalyzed synthesis of oxygen-containing heterocycles via C-H activation has been obtained a significant progress in turn, these achievements also promoted the advance of transition metal-catalyzed C-H functionalization. A broad scope of oxacycles has been synthesized via this approach. Some of these structures are even difficult to access through the conventional methods and hence highlight the palladium-catalyzed C-H activation a powerful and efficient method to achieve novel transformations. 

In summary, palladium-mediated reactions, especially cross-coupling reactions have found many applications in quinoline synthesis. It is noteworthy that due to the a and S activation for the C(2) and C(4) positions, even 2-chloro- and 4-chloro-quinolines are viable substrates for palladium-catalyzed reactions under standard conditions. With the advent of the palladium chemistry and more commercially available organometallic substrates, more palladium-mediated quinoline syntheses are to be added to the repertoire of quinoline chemistry. 

Prashad M (2004) Palladium-Catalyzed Heck Arylations in the Synthesis of Active Pharmaceutical Ingredients. 6 181-204 Pretraszuk C, see Marciniec B (2004) 11 197-248... 

Trost, B.M., Godleski, S.A., Genet, J.P. (1978) A Total Synthesis of Racemic and Optically Active Ibogamine. Utilization and Mechanism of a New Silver Ion Assisted Palladium Catalyzed Cyclization. Journal of the American Chemical Society, 100, 3930-3931. 

Garrett, C.E. and Prasad, K. (2004) The art of meeting palladium specifications in active pharmaceutical ingredients produced by Pd-catalyzed reactions. Advanced Synthesis and Catalysis, 346 (8), 889-900. 

Hydroarylation of alkynoates with phenols is applied to the synthesis of calanolides A 17 and B 18, which are active against AZT-resistant strains of HIV-1.163 The key step is the palladium-catalyzed coumarin formation reaction, as shown in Scheme 18. 

Recently, synthesis of aryl ketones by a combination of palladium-catalyzed C-H activation of arenes and intermolecular carbopalladation of nitriles has been reported (Equation (119)).474... 

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