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 coupling 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.     

Terminal C(sp3)H alkylation of internal alkenes via Ni/H-catalyzed isomerization

An efficient nickel-catalyzed reductive relay cross-coupling of internal alkenes with alkyl (or aryl) halides has been developed. This method has demonstrated broad substrate scope, mild reaction conditions and excellent terminal-selectivity. Moreover, this efficient strategy could be applied to the terminal-selective alkylation of isomeric mixtures of internal alkenes.     

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 coupling reaction of dimethy 3-chlorophthalate (3-DMCP) for 4 h at 70-80 C, 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.     

Synthesis of trisubstituted olefins via nickel-catalyzed decarboxylative hydroalkylation of internal alkynes

A novel NiH-catalyzed decarboxylative hydroalkylation of internal alkynes has been developed. Trisubstituted olefins were obtained in moderate to good yields with good regioselectivities. The reaction involves cis addition of NiH to the internal alkyne. The reaction shows good functional-group tolerance.     

Flexible access to 2,3,5,6-tetrasubstituted dehydropiperidines by Ni- or Co-catalyzed site-selective cross-coupling using Vilsmeier-Haack-derived α-chloro-β-formyltetrahydropyridines

A flexible and cost-effective method for the highly functional group-compatible and site-selective cross-coupling of readily affordable α-chloro-β-formyltetrahydropyridines has been developed, under nickel or cobalt catalysis, leading to the rapid synthesis of 2,3,5,6-tetrasubstituted dehydropiperidines bearing α-amino allylic stereocenters. Cobalt-catalyzed reductive cross-coupling of chloro enaminals with electronically-diverse bromostyrenes as coupling partners proceeds in good yields and with high E/Z selectivity to afford Diels-Alder-suitable cross-conjugated 1,3-dienes.     

Ni-Catalyzed desilylative annulation of benzamides and acrylamides with alkynylsilanes: Access to 3-Methyleneisoindolin-1-one and 5-Methylene-1H-pyrrol-2(5H)-one derivatives

Abstract

The nickel-catalyzed desilylative annulation of C(sp²)–H bonds of benzamides and acrylamides with alkynylsilanes assisted by 8-aminoquinolyl directing group has been reported. A variety of benzamides and acrylamides were compatible in this protocol to construct various 3-methyleneisoindolin-1-one and 5-methylene-1H-pyrrol-2(5H)-one derivatives with Z-configuration selectivity in moderate to high yields.     

Nickel-catalyzed C(sp2)-H selenation of imidazo[1,2-α]pyridines with arylboronic acids or alkyl reagents using selenium powder

A novel and efficient Ni-catalyzed aryl- and alkyl-selenation of imidazo[1,2-α]pyridines employing selenium powder has been developed for the first time. The significant advantages of this protocol are that it is an inexpensive nickel catalyst and exhibits broad functional-group compatibility and good reaction yields.     

Efficient synthesis of hydrocarbon-bridged diaminodiacids through nickel-catalyzed reductive cross-coupling

Solid-phase incorporation of pre-prepared diaminodiacids has been established as an efficient strategy for the chemical synthesis of peptide disulfide bond mimics. Hydrocarbon-bridged diaminodiacids represent one important category of diaminodiacids but they remain difficult to synthesize. In the present work, we reported the use of newly-developed nickel catalyzed reductive cross-coupling reaction to efficiently synthesize diaminodiacids with hydrocarbon bridges. Through optimization of the reaction conditions, the yield of the hydrocarbon bridge formation reached about 50%, even when the reaction was scaled up to the gram level. Subsequently, using our recently developed Dmab/ivDde protecting group system, we obtained a new hydrocarbon-bridged diaminodiacid that are suitable for metal-free deprotection conditions. We demonstrated the utility of this Dmab/ivDde protected hydrocarbon-bridged diaminodiacid in the synthesis of a disulfide surrogate of oxytocin.     

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

Polyimides have been widely used in aerospace and microelectronics due to their excellent mechanical properties and thermo oxidative stability[1].However,most of aromatic polyimides are severe difficult to process because of their bad solubility in common solvents and intractable in their fully imidized forms,which restrict their applications and developments[2,3].     

Synthesis, optical, electrochemical, and thermal properties of α,α′-bis(9,9-bis-n-hexylfluorenyl)-substituted oligothiophenes

A series of new α,α′-bis(9,9-bis-n-hexylfluorenyl)-substituted oligothiophenes with 2-, 4-, and 6-thiophene rings have been synthesized via a nickel-catalyzed reductive dimerization and their optical, electrochemical, and thermal properties investigated. The fluorene substituents have shown electronic interactions with the oligothiophene chains, enhanced the solubility of these materials and stabilized the radical cation and dication by blocking the reactive α-positions of the thiophene moieties. The absorption, fluorescence, electrochemical, and thermal properties of these materials can be tuned by varying the conjugation length of the oligothiophene segment.