Vanadium-Catalyzed Pinacol Coupling Reaction in Water

A catalytic pinacol coupling using water as a solvent was performed by a catalytic amount of vanadium(III) chloride and metallic Al as a co-reductant. A combination forms a binary catalytic system, being in sharp contrast to the reaction in organic solvent, which requires a chlorosilane as an additive. Various aromatic aldehydes underwent the reductive coupling to give the corresponding 1,2-diols in moderate to good yields

Vanadium-Catalyzed Pinacol Coupling Reaction in Water

A catalytic pinacol coupling using water as a solvent was performed by a catalytic amount of vanadium(III) chloride and metallic Al as a co-reductant. A combination forms a binary catalytic system, being in sharp contrast to the reaction in organic solvent, which requires a chlorosilane as an additive. Various aromatic aldehydes underwent the reductive coupling to give the corresponding 1,2-diols in moderate to good yields

A Novel Titanium-Catalyzed Cyclization of Olefinic Iodoethers to Tetrahydrofurans

A catalytic reductive cyclization of olefinic iodoethers was achieved by use of cat. Cp2TiCl2 in the presence of Mn and Me3SiCl. This protocol provides a versatile method for the selective formation of multisubstituted tetrahydrofurans

A Novel Titanium-Catalyzed Cyclization of Olefinic Iodoethers to Tetrahydrofurans

A catalytic reductive cyclization of olefinic iodoethers was achieved by use of cat. Cp2TiCl2 in the presence of Mn and Me3SiCl. This protocol provides a versatile method for the selective formation of multisubstituted tetrahydrofurans

Chirality Organization of Ferrocenes Bearing Dipeptide Chains of Heterochiral Sequence

The symmetrical introduction of two dipeptide chains of heterochiral sequence (-l-Ala-d-Pro-NHPy) into the ferrocene scaffold as a central reverse-turn unit was demonstrated to induce both antiparallel β-sheet-like and type II β-turn-like structures simultaneously, affording the chirality-organized structure. The ferrocene bearing only one dipeptide chain (-l-Ala-d-Pro-NHPy) exhibited a left-handed helically ordered molecular assembly through a network of intermolecular hydrogen bonds instead of intramolecular hydrogen bonds

Induction of γ-Turn-Like Structure in Ferrocene Bearing Dipeptide Chains via Conformational Control

A combination of the ferrocene scaffold as a central reverse-turn unit with the dipeptide chains (-l-Pro-l-Ala-NHPy) was demonstrated to induce both inverse γ-turn-like and antiparallel β-sheet-like structures. Only the antiparallel β-sheet-like structure was formed in the ferrocene bearing the heterochiral dipeptide chains (-l-Pro-d-Ala-NHPy), in which highly organized self-assembly was achieved through a network of intermolecular hydrogen bonds

Synthesis of Highly Strained π-Bowls from Sumanene

Synthesis of Highly Strained π-Bowls from Sumanen

Complexation Stabilized Conformational Regulation of Ferrocene Bearing Podand Dipeptide Chains (-l-Ala-l-Pro-NHPy)

The structural characterization of the palladium complex of the ferrocene 1 bearing podand dipeptide chains (-l-Ala-l-Pro-NHPy) was demonstrated. The ferrocene 1 forms the 1:1 trans complex 2 with PdCl2(MeCN)2 to stabilize the intramolecular conformational regulation in both solution and solid states. The crystal structure of 2 revealed a pseudohelical conformation through palladium binding and chirality organization via sterically constrained moieties (Pro) and intramolecular hydrogen bondings between CO (Ala) and NH (another Ala) of each podand dipeptide chain (N(1)···O(2*), 2.88 Å; N(1*)···O(2), 2.97 Å), giving a 10-membered hydrogen-bonded ring. Such an ordered conformation was supported by the induced circular dichroism. Another noteworthy feature of the ferrocene 1 is its strong tendency to self-assemble through participation of all available hydrogen-bonding donors in the solid state

A Novel Oxovanadium(V)-Induced Oxidation of Organoaluminum Compounds. Highly Selective Coupling of Organic Substituents on Aluminum

A Novel Oxovanadium(V)-Induced Oxidation of Organoaluminum Compounds. Highly Selective Coupling of Organic Substituents on Aluminu

Self-Assembly of Dipeptidyl Ureas: A New Class of Hydrogen-Bonded Molecular Duplexes

The dipeptidyl urea 1 composed of two dipeptide chains bearing the C-terminal pyridyl moiety (-l-Ala-l-Pro-NHPy) was prepared. Two molecules of 1 are revealed to be held together by six intermolecular hydrogen bonds to form a hydrogen-bonded duplex by the single-crystal X-ray structure determination. Proton magnetic resonance nuclear Overhauser effect (NOE) study indicates the hydrogen-bonded duplex even in solution. Furthermore, a shuttle-like molecular dynamics based on recombination of the hydrogen bonds was observed. The dipeptidyl urea composed of two dipeptide chains bearing the C-terminal pyrenyl moiety (-l-Ala-l-Pro-NHCH2Pyr) exhibited both monomer and eximer emissions in the fluorescence spectra, supporting the formation of a duplex. A combination of the C-terminal amide NH function in each side and the designed sequence of hydrogen-bonding sites are considered to be a crucial factor for the duplex formation