Octanuclear Palladacycles with B(3)-H Bond Activation of o-Carborane

Herein,we describe the synthesis of a carborane-supported octanuclear palladacycle complex,Pd_(8)(o-C_(2)B_(10)H_(10)CS_(2)CH_(3))_(4)Cl_(4)(CH_(3)CN)_(4)(complex 1),with B(3)-H activations on o-carborane ligand.The substitution reaction of 1 has been explored,and three of its substituted complexes Pd_(8)(o-C_(2)B_(10)H_(10)CS_(2)CH_(3))_(4)Cl_(4)(L)4(L=^(t)BuNC,2;L=C_(5)H_(5)N,3;L=C_(4)H_(8)S,4)have been synthesized.The m-and p-carborane disubstituted ligands m-and p-C_(2)B_(10)H_(10)(CS_(2)CH_(3))_(2)(ligands 5 and 6)as well as their B—H activated carborane complexes[m-C_(2)B_(10)H_(9)(CS_(2)CH_(3))_(2)PdCl](7)and[p-C_(2)B_(10)H_(8)(CS_(2)CH_(3))_(2)][PdCl(^(t)BuNC)]_(2)(8)have also been synthesized by the similar method.All of these complexes have been characterized,including X-ray single crystal diffraction,NMR spectroscopy,IR spectroscopy and elemental analysis methods.

PEG Click-Triazole Palladacycle： An Efficient Precatalyst for Palladium-Catalyzed Suzuki-Miyaura and Copper-free Sonogashira Reactions in Neat Water

A novel water-soluble, phosphine-free PEG ＂click＂ triazole palladacycle has been successfully synthesized. As a precatalyst, the palladacycle exhibited superior catalytic activity towards Suzuki-Miyaura and copper-free Sonogashira cross-coupling in neat water with the turnover numbers （TONs） of up to 9.8 × 10^5. In addition, the cata- lyst could be reused at least 3 times without significant loss of reactivity.

Palladacycle-Catalyzed Carbonylation of Aryl Iodides or Bromides with Aryl Formates

An efficient palladacycle-catalyzed aromatic carbonylation reaction of aryl formates with aryl iodides or bromides has been developed. Commercially available and easily prepared aryl formates were employed as carbonyl sources without the use of external carbon monoxide. The present catalytic system shows broad functional group tolerance and affords aryl benzoate derivatives in good to excellent yields.

Synthesis and Crystal Structure of Pd(ptac-C,N)(acac-O,O)

A stable organometallic Pd (Ⅱ) compound Pd(ptac-C,N)(acac-O,O) (Hacac = acetyl acetone, Hptac = 3-(2-pyridinethioxy)-acac, formula: C15H17NO4SPd, Mr = 413.76) 1 has been synthesized and its crystal structure was determined by X-ray crystallography. The crystal is of monoclinic with space group C2/c, a = 17.9342(3), b = 17.7791(4), c = 13.1800(1) ? b = 128.400(1), V = 3293.5(1) 3, Z = 8, Dc = 1.669 g/cm3, F(000) = 1664, m = 1.269 mm-1, R = 0.0261 and wR = 0.0710 for 2653 observed reflections (I > 2s(I)). There exist two Pd rings in the title compound, C(14)O(4)PdO(3)C(12)C(13) and C(1)NPdC(8)S, with the palladium atom taking a square-planar coordination. Two oxygen atoms from the acetyl acetone ligand (PdO, 1.991(2) and 2.036(2) ), one N atom (PdN 2.019 ? and the g-carbon atom (PdC 2.067(3) ? from the ptac ligand are coordinated to Pd.

A General Protocol toward Oxindoles Bearing C3-Allylic Quaternary Stereocenter via Domino Reaction:A Concise Synthesis of Heterocycle-Fused Indoline Alkaloids

An efficiently catalytic method toward the synthesis of indolin-2-ones featuring an allylic derived C3-quaternary stereocenter via an intramolecular Heck cyclization/Suzuki coupling of N-substituted-N-(2-bromophenyl)acrylamides and organoboron reagents was successfully developed by using a 1,3-bis(2,6-diisopropylphenyl)acenaphthoimidazol-2-ylidene(AnIPr)-ligated oxazoline palladacycle.It enabled a very broad substrate scope tolerating different functional groups,electronic properties and steric bulkiness.Notably,it revealed a great potential to build diverse heterocycle-fused indoline alkaloids via the same intermediate 3-allyl-1,3-dimethylindolin-2-one.

Palladacyclic N-heterocyclic carbene precatalysts for transition metal catalysis

Palladacycles remain a challenging and significant research field in organic chemistry and have emerged as a type of powerful and versatile precatalysts or key active intermediates for transition metal catalysis.These achievements in this area are correlated to the design and development of useful ancillary ligands,such as N-heterocyclic carbenes(NHCs),which not only stabilize the actual catalytic active species facilitating the transformations,but also provide additional control over the selectivity of reactions.In this context,NHCs-ligated palladacycles(NHCP_(dcycles))with different electronic and steric properties have been synthesized and applied as green precatalysts(high stability and activity,low catalyst loading and mild reaction conditions)to accelerate transition metalcatalyzed reactions.Therefore,this review focuses mainly on the strategy of NHC-Pd_(cycles) design and catalytic results obtained from representative transition metal catalysis,such as Suzuki-Miyaura,Heck-Mizoroki and Sonogashira cross-coupling reactions,Buchwald-Hartwig amination,carbonylation as well as arylation.At last,the current limitations and potential trends for further development of NHC-Pdcycles are also highlighted.