原位生成的水溶性Salen-Pd配合物催化微波促进水中的C-C偶联反应

将一种水溶性Salen,N,N’-双[（5-磺酸基-2-羟基）苄基]缩N,N’-二甲基-1,2-乙二胺（L）与醋酸钯原位生成水溶性Salen-Pd配合物,该水溶性钯配合物应用于催化微波加热的水中的Heck和Sonogashira碳-碳偶联反应.在优化反应条件之后,对溴苯衍生物与乙烯衍生物的Heck偶联反应以及溴苯衍生物与苯乙炔及其衍生物之间的Sonogashira偶联反应进行了考察.发现,在优化的反应条件下,无论是Heck反应,还是Sonogashira偶联反应,都能得到很好的收率.在有机物分离之后,水相继续循环使用4次,在水相的前3次循环使用时,都获得了不错的收率.     

Gold(III) Salen complex-catalyzed synthesis of propargylamines via a three-component coupling reaction

[reaction: see text] Propargylamines have been synthesized by a gold(III) salen complex-catalyzed three-component coupling reaction of aldehydes, amines, and alkynes in water in excellent yields at 40 degrees C. With chiral prolinol derivatives as the amine component, excellent diastereoselectivities (up to 99:1) have been attained. This coupling reaction has been applied to the synthesis of propargylamine-modified artemisinin derivatives with the delicate endoperoxide moieties remaining intact. Cytotoxicities with IC(50) values up to 1.1 microM against a human hepatocellular carcinoma cell line (HepG2) were exhibited by these artemisinin derivatives.     

Generation and trapping of isobenzofuran intermediates formed in the coupling of Fischer carbene complexes and o-alkynylbenzoyl derivatives

[formula: see text] The coupling of o-alkynylbenzoyl derivatives with carbene complexes has been investigated. The reaction initially affords isobenzofuran derivatives, which convert to alkylidenephthalan derivatives or can be trapped by various dienophiles to afford benzo-oxanorbornene derivatives.     

Asymmetric synthesis of α-chiral dihydrocinnamates by catalytic reductive aldol coupling and subsequent dehydroxylation

Optically active dihydrocinnamate derivatives bearing the chiral carbon center at α-position were synthesized by Rh(Phebox)-catalyzed asymmetric reductive aldol coupling reaction with substituted cinnamates and benzaldehyde derivatives and subsequent dehydroxylation reaction.     

Electrooxidative and Regioselective C−H Azolation of Phenol and Aniline Derivatives

A general and practical protocol was developed for the regioselective C?H azolation of phenol and aniline derivatives by electrooxidative cross‐coupling. The reaction occurs under metal‐, oxidant‐, and reagent‐free conditions, allowing access to a wide variety of synthetically useful heteroarene derivatives. The reaction also tolerates a broad range of functional groups and is amenable to gram‐scale synthesis. Finally, a preliminary mechanistic study indicated that a radical–radical‐combination pathway might be involved in the coupling reaction.     

Efficient synthesis of phenanthridinone derivatives via a palladium-catalyzed coupling process

A palladium-mediated domino reaction was developed to conveniently synthesize phenanthridinone derivatives. Phosphine ligand 1 strongly promotes the domino process, which includes aryl-aryl coupling and C-N bond formations concomitant with a deamidation reaction. The versatility and applicability to a broad range of substrates make this reaction useful for the development of bioactive derivatives. [reaction: see text].     

Palladium-catalyzed intermolecular coupling of 3-substituted propargylic carbonates with phenols: Synthesis of 2-substituted benzofuran derivatives

We accomplished the synthesis of 2-substituted benzofuran derivatives by the palladium-catalyzed reaction of 3-substituted propargylic carbonates with phenols. The 2-substituted benzofuran derivatives were obtained through the intermolecular coupling of the 3-substituted propargylic carbonates with phenols, and sequential intramolecular cyclization reaction.     

Selective Lewis acid catalyzed transformation (gamma-butyrolactone versus cyclopropane) of 2-methoxy-4-benzyltetrahydrofuran derivatives. Efficient synthesis of lignan lactones

[reaction: see text]. A short synthesis of lactone lignans exploiting a three-component coupling strategy is presented using a new Lewis acid catalyzed ring-opening/cyclization reaction of 2-methoxytetrahydrofuran derivatives 4 leading to gamma-butyrolactones as a key step. By simply changing the reaction conditions, it was possible, from the same substrates 4, to obtain selectively cyclopropane derivatives.     

An efficient waste-free oxidative coupling via regioselective C-H bond cleavage: Rh/Cu-catalyzed reaction of benzoic acids with alkynes and acrylates under air

[structure: see text]. The direct oxidative coupling of benzoic acids with internal alkynes proceeds efficiently in the presence of a rhodium/copper catalyst system under air to afford the corresponding isocoumarin derivatives. The reaction forms no wastes except for water. Under similar conditions, the aerobic coupling with acrylates also takes place smoothly to produce 7-vinylphthalide derivatives via divinylation and subsequent cyclization.     

Gold-catalyzed multicomponent synthesis of aminoindolizines from aldehydes, amines, and alkynes under solvent-free conditions or in water

A gold(III)-catalyzed multicomponent coupling/cycloisomerization reaction of heteroaryl aldehydes, amines, and alkynes under solvent-free conditions or in water has been developed. This methodology provides rapid access to substituted aminoindolizines with high atom economy and high catalytic efficiency. Especially, the coupling of enantiomerically enriched amino acid derivatives produces the corresponding N-indolizine-incorporated amino acid derivatives without loss of enantiomeric purity.     

New Heck-type reaction applied to the synthesis of protoporphyrin-IX derivatives

[reaction: se text] A new Heck-type reaction under catalysis by Pd for obtaining polysubstituted arylvinylydene derivatives of porphyrin systems is reported. The coupling between the Zn(II)-protoporphyrin-IX dimethylester Zn-2 and several bromo-aryl and iodo-aryl compounds in the presence of a new Pd catalyst has been studied. This coupling reaction, although providing moderate regioselectivity, gives quantitative conversion.     

Phenyltrisalanine: a new,C3-symmetric,trifunctional amino acid

Two derivatives of phenyltrisalanine, a new, trifunctional amino acid, were synthesised in optically active forms. Two complementary techniques were employed, an HWE olefination reaction or a Heck coupling reaction, and the resulting dehydroamino acids were hydrogenated using a chiral Rh(I)–Et-DuPHOS catalyst. Phenyltrisalanine derivatives of excellent stereoisomeric purities were thus obtained.     

A synthetic strategy leading to monodisperse PPV oligomers by coupling reactions of vinyltrimethylsilanes

A novel strategy for the synthesis of well-defined oligo(phenylenevinylene)s was developed. The procedure is entirely based upon two coupling processes, both involving vinyltrimethylsilanes. Bis(styryl)benzenes 2a-g bearing two octyloxy groups in the central aromatic ring and various substituents on the external aromatic rings were prepared in good yield by a regio- and stereoselective coupling reaction of 1 with different arenediazonium tetrafluoroborates. Oligomers with a more extended conjugated system, 4a-c, and with m-phenylene subunits 13a,b, were also readily obtained by conversion of the unsaturated trimethylsilyl derivatives 3a,c,d to the corresponding boron derivatives and a subsequent coupling reaction with compounds 2a and 2c.     

Natural and synthetic polymers as reagents. I. Diazonium salt derivatives of polycarboxylic resins (insoluble diazonium salt chromogens)

A method is described for the preparation of insoluble polymeric diazonium-salt chromogens which have a precise composition and well-defined specific reactivity and which are capable of undergoing coupling reactions to produce highly colored azo derivatives. The technique involves reaction of the acid chloride of an acrylic or methacrylic acid polymer crosslinked with divinylbenzene with an aromatic diamine, followed by diazotization of the free amino groups of the resultant aminoarylamido resin to give an insoluble diazonium salt. The aminoarylamido derivatives, the corresponding diazonium salts, and colors of the azo derivatives obtained in coupling reactions are tabulated.     

Divergent synthesis of fused Benzo-xanthene and oxazine derivatives via Cu-catalyst

Cu-Cu₂O combination showed synergic effects in catalyzing intramolecular Ullmann coupling reaction for halo-Betti bases to afford fused benzo-xanthenes from both electron-rich and electron-deficient aromatic systems in good yield under mild reaction conditions. The sterically hindered halo-Betti bases also provided products in excellent yield. Under optimized condition, a gram scale reaction was also performed to afford the product in excellent yield. However, without ortho-halo substituted Betti-bases failed to afford fused benzo-xanthene derivatives. Exploring the reaction optimization without Cu metal, serendipitously it was produced 1,3-oxazine derivatives in excellent yield via intramolecular cross-dehydrogenative coupling (CDC) reaction. Similarly, electron-rich, electron-deficient and sterically hindered Betti-bases provided the products in good to excellent yield under mild condition.     

Access to C(sp3)-C(sp2) and C(sp2)-C(sp2) bond formation via sequential intermolecular carbopalladation of multiple carbon-carbon bonds

A synthetic strategy of 4-benzyl-substituted 1,3-butadiene derivatives through Pd-catalyzed three-component coupling reaction of benzyl chlorides, alkynes, and monosubstituted alkenes is described. This tandem coupling reaction forms a C(sp(3))-C(sp(2)) bond and a C(sp(2))-C(sp(2)) bond sequentially in a single-step operation.     

Synthesis of thiophene derivatives via palladium-catalyzed coupling reactions

Thiophene derivatives with multiple substitutions are prepared from vinylidene bromide, which is synthesized by the reaction of thiophene-2-carboxaldehyde with carbon tetrabromide in the presence of PPh₃, as a core molecule through several coupling reactions such as Suzuki-Miyaura coupling and palladium-catalyzed CH arylation. The reactions with a wide variety of organic halides lead to a series of substituted thiophene derivatives in moderate to good yields.     

Oxidative arylation of isochroman

We report the use of a previously intractable nucleophile, anisole, in an oxidative "cross-dehydrogenative coupling" (CDC) reaction with the cyclic ether isochroman, as well as derivatives of both components. Metal catalysis was required for the reaction to proceed efficiently, and the reaction is highly sensitive to modification of either coupling partner but is able to produce a range of novel compounds via what is a synthetic alternative to the traditional oxa-Pictet-Spengler reaction.     

Synthesis of novel 9-aryl and heteroarylpurine derivatives via copper mediated coupling reaction

A series of 9-(hetero)arylpurine derivatives has been prepared through N-arylation of 6-chloropurine with boronic acids in the presence of copper(II) acetate. Screening reaction conditions in terms of bases and solvents led to the successful coupling of a series of sterically demanding (hetero)arylboronic acids, never described so far. The coupling products were next readily converted into the target adenine derivatives. The described procedure provides easy access to original fragments for screening applications. Moreover these 9-aryl-6-chloropurine derivatives might be useful as intermediates for the preparation of purine derivatives with potential biological properties.     

Recent advances in oxidative C–C coupling reaction of amides with carbon nucleophiles

The C–C coupling reaction of N-electron withdrawing group (EWG) protected amides with coupling partners is one of the most important methods for C–C bond formation at the α-position of amides to directly give α-substituted amides. Of the four reactions, namely, the reaction via the generation of carbanion with an electrophile, that via the generation of carbon radical with a radical donor, that via the generation of iminium ion species with a nucleophile (oxidative coupling reaction), and that using a transition metal carbenoid, the oxidative coupling reaction presents a challenge although the reaction products are very useful for the transformation of a wide range of nitrogen-containing derivatives. In this review, recent developments in the oxidative coupling reaction of N-EWG protected amides with nucleophiles are summarized with focus on the reaction using a transition metal, the transition-metal-free reaction, the enantioselective reaction using a chiral catalysts, and the organocatalyzed oxidative coupling reaction.