Suzuki-Miyaura coupling reaction

In this study we show that the Pd/C catalyzed Suzuki-Miyaura coupling reaction can be performed in a microwave oven. Overall the microwave synthesis is faster than comparable thermal methods and the combination of the ease of use of the microwave oven and the facile work-up with Pd/C makes this a very efficient method for performing coupling reactions. 

A variety of triazole-based monophosphines (ClickPhos) 141 have been prepared via efficient 1,3-dipolar cycloaddition of readily available azides and acetylenes and their palladium complexes provided excellent yields in the amination reactions and Suzuki-Miyaura coupling reactions of unactivated aryl chlorides <06JOC3928>. A novel P,N-type ligand family (ClickPhine) is easily accessible using the Cu(I)-catalyzed azide-alkyne cycloaddition reaction and was tested in palladium-catalyzed allylic alkylation reactions <06OL3227>. Novel chiral ligands, (S)-(+)-l-substituted aryl-4-(l-phenyl) ethylformamido-5-amino-1,2,3-triazoles 142,... 

Table 4 Suzuki and Suzuki-Miyaura coupling reactions of halogenopyrazines...

Table 21 Summary of the results obtained for the Suzuki-Miyaura coupling reactions conducted using an in situ fabricated PA-TAP-Pd membrane...

Iron-catalyzed Suzuki-Miyaura coupling reactions were also reported by Nakamura and colleagues (entry 27) [67]. Alkyl halides 1 and mixed pinacol aryl(butyl)borates, generated in situ from arylboronates and butyllithium, were used as the reagents and 10 mol% of the iron complexes 16a or 16b as the catalysts. The addition of 20 mol% of MgBr2 was essential for the success of the reaction. Products 3 were isolated in 65-99% yield. The methodology tolerates ester and nitrile functions. The reaction starts probably by initial boron-iron transmetalation to generate a diaryliron(II) complex. 

Fig. 2 Nickel-catalyzed alkyl-alkyl and alkyl-aryl Suzuki-Miyaura coupling reactions...

This chemistry features in a synthesis of the left hand fragment of yessotoxin and adriatoxin <02OL3943>. Assembly of the F-N ring component of gymnomycin A, involves a b-alkyl Suzuki-Miyaura coupling reaction <02OL1747>. 

Since Suzuki-Miyaura coupling reactions are easy to perform, functionalised carbenes have often been tested in this catalysis, but with mediocre to poor results [89-91]. In retrospect, this is easily understood, since the best results are obtained for bulky trans-biscarbene complexes and functionalised NHC usually provide cix-chelate complexes [92]. However, the Suzuki-Miyaura reaction was used to evaluate the electronic properties of annulated carbenes [93,94]. 

In a detailed investigation of the mechanism and scope of palladium catalyzed amination of five-membered heterocycles, the 1-methyl-3-bromoindole 145 was aminated with secondary amines to the 3-aminoindoles 146. Similar results were obtained for l-methyl-2-bromoindole <03JOC2861>. Rhodium-catalyzed cyclopropanation reactions involving 1-methyl-3-diazooxindole and exocyclic alkenes provided novel dispirocyclic cyclopropanes <03SL1599>. New applications of palladium-mediated cross-coupling reactions have been utilized to prepare a variety of functionalized indoles. Suzuki-Miyaura coupling reactions of indole-3-boronates <03H(59)473> and indole-5-boronates <03H(60)865> were utilized to prepare inhibitors of lipid peroxidation and melatonin analogues, respectively. 

An efficient, diverse synthesis of oxazolo[4,5-c]quinoline-4-ones and thiazolo[4,5-c]quinolines-4-ones is carried out in two steps from readily available starting materials <03OL2911>. The Suzuki-Miyaura coupling reaction was employed. 

A highly regioselective microwave promoted synthesis of 2-aryl-6-chloro-benzothiazoles (xxxviii) by the Suzuki-Miyaura coupling reaction of 2,6-dic-hlorobenzothiazole with arylboronic acids is given by Heo et al. [58]. 

Heo Y, Song YS, Kim BT et al (2006) A highly regioselective synthesis of 2-atyl-6-chlorobenzothiazoles employing microwave-promoted Suzuki-Miyaura coupling reaction. Tetrahedron Lett 47 3091-3094... 

Catalyst development for Pd-catalyzed Suzuki-Miyaura coupling reactions. B(OH)2... 

An alternative sol-gel strategy has been reported for the preparation of a closely related material. Using the approach of the initial grafting of the imidazolium cation onto pre-dried silica, followed by treatment with PdCl2, non-acidic supported palladium-based ILs were also prepared and used in Suzuki-Miyaura coupling reactions. ... 

Several examples are reported inTable 5.5-4. These esters are well suited for Heck and Suzuki-Miyaura coupling reactions. 

Suzuki-Miyaura coupling, involving the reaction of aryl boronic derivatives with aryl halides in the presence of a palladium catalyst, is a very powerful method for the preparation of biaryls. Solutions of aryl bromides or iodides supported on onium salts via an ester link in an RTIL lead to BTSILs that can be engaged in the Suzuki-Miyaura coupling reaction with aryl boronic derivatives. like the Heck reaction, this coupling is also sensitive to the variations in different parameters. The possibility to synthesize libraries of biarylic derivatives by parallel synthesis is illustrated by (Scheme 5.5-39) [51]. 

---