Chiral palladium bis(phosphite) PCP-pincer complexes via ligand C–H activation

Abstract

The synthesis of a range of chiral palladium bis(phosphite) pincer complexes has been achieved via C-H activation of the parent ligands and one of the complexes formed shows good activity in the catalytic allylation of aldehydes.

Facile synthesis of achiral and chiral PCN pincer palladium(II) complexes and their application in the Suzuki and copper-free Sonogashira cross-coupling reactions

“…Further reduction in the amount of the catalyst led to a gradual decrease in the yields under the same reaction conditions (entries [13][14]. By using 0.1-0.3 mol% of 2a, coupling of several aryl bromides with PhB(OH) 2 could also afford the coupled products in good to excellent isolated yields (entries [15][16][17][18][19][20][21][22]. Finally, the relative catalytic activities of PCN pincer Pd complexes 2a-e as well as the corresponding symmetrical PCP complex [PdCl{C 6 H 3 -2,6-(OPPh 2 ) 2 }] (3) in the Suzuki reaction were investigated (Table 5).…”

“…Due to the existence of the Pd-C r bonds supported by two ortho,ortho-chelated heteroatom groups in the molecules, these complexes usually exhibit high stabilities towards heat, air and moisture. Furthermore, the reactivity of the Pd center can be finely tuned by adjusting the steric and electronic properties of heteroatom donors and substituents thereon [10][11][12][13][14][15][16][17][18][19][20]. Consequently, various types of PCP or NCN pincer palladium complexes have been found to be efficient catalysts for a variety of C-C bond forming reactions including the Heck reaction [10,13,14,21], Suzuki coupling [16,22,23], Sonogashira coupling [15] and a-arylation of ketones [24].…”

PCN‐ and PCS‐Pincer Palladium Complexes as Tandem Catalysts in Homoallylation Reactions

“…[6] It is worthy of note that several pincer palladium complexes have been reported as active catalysts for only one of the two reactions that are part of this tandem reaction. [6,[8][9][10] For example, the corresponding PCP-pincer palladium complex [PdA C H T U N G T R E N N U N G {C 6 H 3 A C H T U N G T R E N N U N G (CH 2 PPh 2 ) 2 -2,6}A C H T U N G T R E N N U N G (MeCN)]A C H T U N G T R E N N U N G (BF 4 ) is an active catalyst in the homoallylation of aldehydes or sulfonimines with allylstannane, [8a] but is not able to catalyze the stannylation reaction. Vice versa, NCN-pincer palladium complexes catalyze the stannylation reaction, but not the homoallylation.…”

Complejos pincer y su comportamiento como iniciadores en polimerización de etileno

“…A continuación se muestran algunos métodos: 1) Ciclometalación de ligandos del tipo DCD por activación del enlace C-H en el anillo aromático central: es el método más simple y directo. Consiste en hacer reaccionar el ligando pincer con el respectivo precursor del metal (Figura 4) (Baber et al, 2006). 2) Adición oxidativa; consiste en la reacción entre un haluro de arilo precursor por ejemplo; NC(Br)N y un compuesto metálico en estado de oxidación cero(0), esta metodología es muy utilizada cuando no se puede obtener complejos pincer por activación directa del enlace C-H. Mediante esta ruta se pueden sintetizar complejos NCN (Figura 5) (Alsters et al, 1992).…”