Cobalt-Catalyzed Chemo- and Stereoselective Transfer Semihydrogenation of 1,3-Dienes with Water as a Hydrogen Source.

()-1,2-Disubstituted, trisubstituted, and tetrasubstituted alkenes are not only important units in medicinal chemistry, natural product synthesis, and material science but also useful intermediates in organic synthesis. Development of catalytic stereoselective transformations to access multisubstituted alkenes with various substitution patterns from easily accessible modular starting materials and readily available catalysts is a crucial goal in the field of catalysis. Water is an ideal hydrogen source for catalytic transfer hydrogenation despite of the high difficulty to activate water.

Catalytic Regio- and Enantioselective Remote Hydrocarboxylation of Unactivated Alkenes with CO.

The catalytic regio- and enantioselective hydrocarboxylation of alkenes with carbon dioxide is a straightforward strategy to construct enantioenriched α-chiral carboxylic acids but remains a big challenge. Herein we report the first example of catalytic highly enantio- and site-selective remote hydrocarboxylation of a wide range of readily available unactivated alkenes with abundant and renewable CO under mild conditions enabled by the SaBOX/Ni catalyst. The key to this success is utilizing the chiral SaBOX ligand, which combines with nickel to simultaneously control both chain-walking and the enantioselectivity of carboxylation.

Cu-mediated enantioselective C-H alkynylation of ferrocenes with chiral BINOL ligands.

A wide range of Cu(II)-catalyzed C-H activation reactions have been realized since 2006, however, whether a C-H metalation mechanism similar to Pd(II)-catalyzed C-H activation reaction is operating remains an open question. To address this question and ultimately develop ligand accelerated Cu(II)-catalyzed C-H activation reactions, realizing the enantioselective version and investigating the mechanism is critically important. With a modified chiral BINOL ligand, we report the first example of Cu-mediated enantioselective C-H activation reaction for the construction of planar chiral ferrocenes with high yields and stereoinduction.

Access to Sulfoxides under NHC/Photocatalysis via a Radical Pathway.

A photocatalyzed transformation from sulfinic acids to sulfoxides under visible-light irradiation in the presence of N-heterocyclic carbene is established. Various alkyl groups from four-substituted Hantzsch esters or Meyer nitriles are smoothly converted to the corresponding sulfoxides through a radical coupling pathway in the presence of 1,1-carbonyldiimidazole. This method allows sulfoxide synthesis to refrain from relying on the oxidation of sulfides and provides an alternative route for the preparation of sulfoxides.

S(vi) in three-component sulfonamide synthesis: use of sulfuric chloride as a linchpin in palladium-catalyzed Suzuki-Miyaura coupling.

Sulfuric chloride is used as the source of the -SO- group in a palladium-catalyzed three-component synthesis of sulfonamides. Suzuki-Miyaura coupling between the generated sulfamoyl chlorides and boronic acids gives rise to diverse sulfonamides in moderate to high yields with excellent reaction selectivity. Although this transformation is not workable for primary amines or anilines, the results show high functional group tolerance.

Generation of Sulfonylated Tetrazoles through an Iron-Catalyzed Multicomponent Reaction Involving Sulfur Dioxide.

As a privileged motif, tetrazoles can be widely found in pharmaceuticals and materials science. Herein, a five-component reaction of cycloketone oxime esters, alkynes, DABCO·(SO), and two molecules of trimethylsilyl azide under iron catalysis is developed, giving rise to a range of cyano-containing sulfonylated tetrazoles in moderate to good yields. This multicomponent reaction exhibits excellent selectivity and enables the formation of multiple new chemical bonds in one pot.

Photoredox-catalyzed synthesis of sulfones through deaminative insertion of sulfur dioxide.

Katritzky salts are used as the alkyl radical precursors with the insertion of sulfur dioxide under photoredox catalysis. This transformation first enables direct generation of various alkylsulfonyl radicals by photoinduced single electron reduction, leading to diverse dialkyl sulfones in good to excellent yields. A radical pathway is proposed under visible-light induced conditions with the insertion of sulfur dioxide.

Generation of β-Halo Vinylsulfones through a Multicomponent Reaction with Insertion of Sulfur Dioxide.

A four-component reaction of terminal alkynes, aryldiazonium tetrafluoroborates, sulfur dioxide surrogate of DABCO⋅(SO ) , and potassium halide in the presence of copper(I) chloride (10 mol %) gives rise to β-halo vinylsulfones with good stereoselectivity. The vicinal difunctionalization of alkynes through sulfonylation and halogenation with the insertion of sulfur dioxide works efficiently. A plausible mechanism is proposed, which includes a radical process.

Vicinal Difluoroalkylation and Aminosulfonylation of Alkynes under Photoinduced Conditions.

A photoinduced vicinal difluoroalkylation and aminosulfonylation of alkynes under photocatalysis was realized. The combination of ethyl 2-bromo-2,2-difluoroacetate, alkynes, and DABCO⋅(SO ) with hydrazines, catalyzed by 9-mes-10-methyl acridinium perchlorate in the presence of visible light, afforded (E)-ethyl 2,2-difluoro-4-aryl-4-sulfamoylbut-3-enoates in good yields with high stereoselectivity. This four-component reaction proceeds through radical addition with the insertion of sulfur dioxide.

Highly Efficient Formal [2+2+2] Strategy for the Rapid Construction of Polycyclic Spiroindolines: A Concise Synthesis of 11-Demethoxy-16-epi-myrtoidine.

A novel formal [2+2+2] strategy for the stereoselective elaboration of polycyclic indole alkaloids is described. Upon treatment with the catalyst InCl3 (5 mol %), tryptamine-derived enamides reacted readily with methylene malonate, thus enabling rapid and gram-scale access to versatile tetracyclic spiroindolines with excellent diastereoselectivity (21 examples, up to 95 % yield, up to d.r.

Enantioselective double manipulation of tetrahydroisoquinolines with terminal alkynes and aldehydes under copper(I) catalysis.

Tetrahydroisoquinoline alkaloids with a C1 stereogenic center are a common unit in many natural and non-natural compounds of biological importance. Herein we describe a novel Cu(I) -catalyzed highly chemo- and enantioselective synthesis of chiral tetrahydroisoquinoline-alkaloid derivatives from readily available unsubstituted tetrahydroisoquinolines, aldehydes, and terminal alkynes in the presence of the ligand (R,R)-N-pinap. This synthetic operation installs two substituents in the 1- and 2-positions.

Cadmium iodide-mediated allenylation of terminal alkynes with ketones.

Allenes are important building blocks in organic synthesis and have attracted much attention from researchers worldwide. So far, mono- and 1,3-disubstituted allenes can be prepared easily by applying the allenylation of terminal alkynes reaction of aldehydes. However, trisubstituted allenes have never been reported using this reaction due to the extremely low reactivity of ketones.

CuBr for KA(2) reaction: en route to propargylic amines bearing a quaternary carbon center.

A highly efficient CuBr-catalyzed coupling of ketones, amines and alkynes (KA(2)) forming propargylic amines bearing a quaternary carbon center with the broadest scope so far has been developed.

Catalytic asymmetric synthesis of optically active allenes from terminal alkynes.

CuBr and ZnI(2) have been developed as catalysts or subcatalysts for the efficient asymmetric synthesis of axially chiral allenols with up to 97% ee from readily available propargylic alcohols, aliphatic or aromatic aldehyde, pyrrolidine, and commerically available ligands. The alcohol unit in the terminal alkynes plays a very important role for ensuring high enantioselectivity via coordination.

A series of 64 cases of pancreatic cystic neoplasia from an institutional study of China.

Aim: To recognize cystic neoplasia of the pancreas and thus to identify a panel of curable diseases.

Methods: Sixty-four cases of cystic neoplasia of the pancreas, including 28 cases of intraductal papillary mucinous neoplasia (IPMN), 12 cases of serous cystic neoplasia (SCN), 11 cases of mucinous cystic neoplasia (MCN), 11 cases of solid pseudo-papillary neoplasia (SPN), and 2 cases of solid tumor with cystic degeneration were examined immunohistochemically for their expression of MUC1, MUC2, MUC4, MUC5AC, and MUC6, as well as other related antigens.

Results: Adenoma type of IPMN and borderline lesions exhibited high expressions of MUC2, and MUC5AC.