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Kopylovich MN, Lasri J, Guedes da Silva MF, Pombeiro AJ: Single-pot template transformations of cyanopyridines on a Pd (II) centre: syntheses of ketoimine and 2,4-dipyridyl-1,3,5-triazapentadiene palladium (II) complexes and their catalytic activity for microwave-assisted Suzuki-Miyaura and Heck reactions. Dalton Trans. 2009 Apr 28;(16):3074-84. Epub 2009 Mar 2.
[2 + 3] cycloaddition of the pyrrolin N-oxide (-) O [upper bond 1 start](+) N [double bond, length as m-dash] CHCH (2) CH (2) C [upper bond 1 end] Me (2) with 2-cyanopyridine NC (5) H (4)(2-CN) in the presence of PdCl (2) at room temperature in acetone gives the ketoimine palladium (II) complex cis-[PdCl (2){N (=[upper bond 1 start] CCH (2) CH (2) C (Me)(2) N [upper bond 1 end] H) C (=O) C (5) H (4) N}] containing the (E)-N-(5,5-dimethylpyrrolidin-2-ylidene) picolinamide ligand, in good yield (85%). The reaction of with 3-cyanopyridine NC (5) H (4)(3-CN) or 4-cyanopyridine NC (5) H (4)(4-CN) under the same experimental conditions gives the simple adducts of cyanopyridines trans-[PdCl (2){NC (5) H (4)(3-CN)}(2)] or trans-[PdCl (2){NC (5) H (4)(4-CN)}(2)] , respectively. When the cyanopyridines NC (5) H (3) R (1) R (2) (R (1) = 2-CN, R (2) = H ; R (1) = 3-CN, R (2) = H ; R (1) = 4-CN, R (2) = H ; R (1) = 4-CN, R (2) = 2-Cl ; R (1) = 3-CN, R (2) = 5-Me ) are heated at 100 degrees C for 12 h with 2-butanone oxime (used as a reagent and solvent) in the presence of PdCl (2), the 2,4-dipyridyl-1,3,5-triazapentadienate (or bis-imidoylamidinate) palladium (II) complexes [Pd{HN [double bond, length as m-dash] C (NC (5) H (3) R (2)) NC (NC (5) H (3) R (2))[double bond, length as m-dash] NH}(2)] (2-NC (5) H (3), R (2) = H ; 3-NC (5) H (3), R (2) = H ; 4-NC (5) H (3), R (2) = H ; 4-NC (5) H (3), R (2) = 2-Cl ; 3-NC (5) H (3), R (2) = 5-Me ) are synthesized by one-pot template transformations followed by deprotonation by a base (n-PrNH (2)). The compounds were characterized by IR, (1) H and (13) C NMR spectroscopies, FAB (+)-MS, elemental analyses and, in the cases of , , and , also by X-ray diffraction analyses. The catalytic activity of complexes and was studied under microwave irradiation for C-C coupling reactions, in the solid phase on a silica gel support, and it was found that complex is the most active one with the maximum TON of 2.0.10 (5) and TOF of 1.3.10 (4) min (-1) for Suzuki-Miyaura, and TON of 800 and TOF of 27 min (-1) for Heck reactions. |
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