Nickel-Catalyzed Regioselective Hydrosilylation of Conjugated Dienes

With the increasing demand for homoallylic silanes and allylic silanes,the highly efficient and regioselective hydrosilylations of conjugated dienes are urgently needed.Herein,we developed a Ni-catalyzed regiodivergent hydrosilylation of aromatic conjugated dienes by adjusting the temperature and ligands.Under low temperature(-30℃),an eternal-ligand-free system(Ni/t-BuOk)can efficiently facilitate the 3,4-anti-Markovnikov hydrosilylation to provide homoallylic silanes via electrophilic activation process;under room temperature(25℃),a ligand-controlled system(Ni/t-BuOk/PPh3)can eventuate the 3,4-Markovnikov hydrosilylation to produce allylic silanes via Chalk-Harrod process.Both systems are compatible with various conjugated dienes and primary silanes in excellent yields andregioselectivities.

Nickel-catalyzed reductive coupling of glucosyl halides with aryl/vinyl halides enabling β-selective preparation of C-aryl/vinyl glucosides

This work describes stereoselective preparation ofβ-C-aryl/vinyl glucosides via mild Ni-catalyzed reductive arylation and vinylation of C1-glucosyl halides with aryl and vinyl halides.A broad range of aryl halides and vinyl halides were employed to yield C-aryl/vinyl glucosides in 42%–93%yields.Good to excellentβ-selectivities were obtained for C-glucosides by using tridentate ligand.

A Facile and Efficient Synthesis of N,N-Dimethylarylamines from Aryl Bromides

Catalytic amination of aryl bromides with in situ generated dimethylamines from N, N- dimethylacetamide (DMA) has been successfully carried out using Ni(Phen)Cl2 as catalyst. Both electron-rich and electron-poor aromatic system reacted smoothly under the conditions to give N,N-dimethylarylamines in good yields.

A novel efficient synthetic method for 2,2′,3,3′-biphenyltetracarboxylic dianhydride

A novel approach to the synthesis of 2,2＇,3,3＇-biphenyltetracarboxylic dianhydride is described. The target compound was prepared by a nickel-catalyzed couplirtg reaction of dimethy 3-chlorophthalate （3-DMCP） for 4 h at 70-80 ℃, followed by subsequent hydrolysis of tetra-ester in acid solution and dehydration of tetra-acid, with overall yield of 68%. The structures of the products were characterized by IR, 1H NMR and ^13C NMR respectively.

Microwave Accelerated Synthesis of 2,2',3,3'-Biphenyltetracarboxylic Dianhydride

Polyimides have been widely used in aerospace and mi- croelectronics due to their excellent mechanical properties and thermo oxidative stability^[1]. However, most of aromatic polyi- mides are severe difficult to process because of their bad solu- bility in common solvents and intractable in their fully imidized forms, which restrict their applications and developments^[2,3]. Therefore, many investigations were focused on improving the dissolvability of polyimides and it was found that the excellent solubilizing units could be obtained from substituted biphenyls^[4-7]. Biphenyltetracarboxylic dianhydrides（BPDAs） are the most important monomers for the synthesis of these compounds. Among them, the synthesis of 2,3,3＇,4＇-/3,3＇,4,4＇- biphenyltetracarboxylic dianhydride has been widely investi- gated, but only a few literatures reported the synthesis of 2,2＇,3,3＇-biphenyltetracarboxylic dianhydride（i-BPDA）^[8-10].

Ni-catalyzed highly regio- and stereo-selective diborylative cyclization of 1,6-enynes with diboron reagent

The Ni-catalyzed highly selective diborylative cyclization of 1,6-enynes with diboron reagent has been developed. When pinB-Bdan was used, multiple types of boron-containing functional groups could be installed into organic molecule with great chemoselectivity and regioselectivity though this reaction. Meanwhile, if B_2pai_2 was employed, the asymmetric diborylative cyclization could be well induced by using strategy of dynamic kinetic resolution. Importantly, the above reactions could afford desired product with 100% atomic economy, and could be compatible with different series of substituents. The studies of further transformation well illustrated that different type products could serve diverse synthetic strategy. Notably, the reaction mechanism was intensively studied by density functional theory(DFT) calculations, which could reveal the mechanism of regio- and enantio-selective control.