Carbon-nitrogen Double Bond Research Articles

Homo- and heterogeneous organocatalysis: enantioselective Mannich addition of ketones to endocyclic carbon–nitrogen double bonds

The proline-catalyzed Mannich addition of ketones to chalkogenazines is reported. Yields and enantioselectivities of the corresponding products were good to excellent, using different types of organocatalysts. Furthermore the immobilization of hydroxyproline into a readily synthesized polystyrene-copolymer was accomplished. The catalytic performance of this heterogeneous catalyst was successfully demonstrated in the discussed Mannich reaction.

ChemInform Abstract: Highly Enantioselective Alkylation of Carbon-Nitrogen Double Bonds. Catalytic and Stoichiometric Asymmetric Synthesis of Optically Active Amines by the Enantioselective Addition of Dialkylzinc Reagents to N- Diphenylphosphinoylimines.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: 1,3-Dipolar Cycloaddition Reactions of 1,3,4-Oxadiazin-6-ones with Nitrile Oxides.

2,5-Diaryl-1,3,4-oxadiazin-6-ones 1 gave with nitrile oxides 2 1,2,4-oxadiazole derivatives 4. When mesitonitrile oxide 2a was used, bis-adducts 3 were also formed. The cycloadditions showed a remarkable site selectivity towards one carbon nitrogen double bond. The structure of both adducts was fully characterized by X-ray analysis.

ChemInform Abstract: Asymmetric Induction in Additions to Carbon-Oxygen and Carbon-Nitrogen Double Bonds

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Preparation of Perfluoroalkyl Azaarenes with a Perfluoroalkyllithium- Boron Trifluoride System.

Abstract In the presence of boron trifluoride, perfluoroalkyllithiums generated in situ from tbe reaction of n-perfluoroalkyl iodides with methyllithium-lithium bromide smoothly added to a carbon-nitrogen double bond of bicyclic azaarenes and diazines to give the corresponding perfluoroalkylated dihydro heterocycles, which often underwent spontaneous aromatization in air. Perfluoroalkylation occurred preferentially at the carbon next to nitrogen in azaarenes even when the carbon atom was occupied by an alkyl substituent. Only one exception observed was the reaction of acridine where a perfluoroalkyl group was introduced at 9 position.

ChemInform Abstract: Boron Trifluoride Assisted Perfluoroalkylation of Carbon-Nitrogen Double Bonds.

In the presence of BF 3 -OEt 2 , (perfluoroalkyl)lithiums generated in situ from the reaction of primary perfluoroalkyl iodides and MeLi-LiBr reacted with imines, azines, and nitrones to afford perfluoroalkylated nitrogen-containing compounds in moderate to good yields. This method was successfully applied to the preparation of a (perfluoroalkyl)glycine and optically active perfluoroalkylated amines

Synthesis and Reactivity of Sulfur(II) Dications Stabilized Using Monodentate Ligands

The stoichiometric 1:2:2 reaction of SCl(2), trimethylsilyl trifluoromethanesulfonate, and pyridine produced sulfur(II) dications featuring two pyridine donors. The complexes were reacted with unsaturated organic substrates, which displayed addition with carbon-carbon and carbon-nitrogen double bonds. The substitution on the para position of the ligand was varied by using electron donating, electron withdrawing, and neutral groups. The electronics at this position were determined to have a substantial effect on the outcome of the reaction. The presence of an electron donating group increased the Lewis basicity sufficiently to completely stop the reaction, whereas an electron withdrawing group decreased the reaction time. These observations are unique to the chemistry of sulfur(II) dications and main group polycations as a whole.

ChemInform Abstract: Dimethylammonium Chlorochromate Adsorbed on Alumina: A Mild, Convenient and Inexpensive Reagent for Cleavage of Carbon-Nitrogen Double Bonds under Non-Aqueous Condition.

ChemInform Abstract: Dimethylammonium Chlorochromate Adsorbed on Alumina: A Mild, Convenient and Inexpensive Reagent for Cleavage of Carbon-Nitrogen Double Bonds under Non-Aqueous Condition.

ChemInform Abstract: Trimethylammonium Chlorochromate (TMACC) Adsorbed on Alumina for Cleavage of Carbon-Nitrogen Double Bonds under Non-Aqueous Conditions.

ChemInform Abstract: Trimethylammonium Chlorochromate (TMACC) Adsorbed on Alumina for Cleavage of Carbon-Nitrogen Double Bonds under Non-Aqueous Conditions.

ChemInform Abstract: Alkylative Amination of Aldehydes via Carbon-Carbon Bond Formation Based on Radical Addition to Carbon-Nitrogen Double Bond.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Isothiouronium Salts Based on Anthracene and Pyrene as Anion Sensors

showed two sets of peaks for the protons, thus indicating the existence of two different isomers at ratios of 1 : 1 and 3 : 2, respectively (Figure 1 and Experimental section).It is well known that isomerism can occur in isothiouronium salts by three possible mechanisms, viz. the oscillation of the carbon-nitrogen double bond, the hindered rotation at the C=N bond and the restricted rotation at the C=S bond.

Flash vacuum thermolysis generation and a UV-photoelectron spectroscopy study of the N-substituted iminoacetonitriles

Flash vacuum thermolysis of cis and trans 1-benzyl and 1-allyl-2-cyano-3-phenylzetidines ( 1a and 1b) at 470 °C resulted in the formation of E and Z isomers of N-benzyl and N-allyl iminoacetonitriles 2a and 2b, respectively, beside small amounts of products 3a and 3b of their [1,3] prototropic shifts. It was found that the thermal fragmentation of the azetidine ring occurred fully regioselectively with a cleavage of the C2–C3 and C4–N bonds, but not the N–C2 and C3–C4 bonds. The UV-photoelectron spectrum of compound 2b was measured and analyzed with the aid of quantum chemical calculations of ionization energies. The strong modification of the electronic structure of the simplest carbon–nitrogen double bond upon the α,β substitution is due to the combined electron-withdrawing effect of the nitrile group and the donor effect of the allyl group.

Chemoselective reaction of cyanoacetic acid with benzal-4-acetylanilines and fungitoxicity of products

Cyanoacetic acid reacted chemoselectively with carbon-nitrogen double bond of benzal-4-acetylaniliines, leaving the carbon-oxygen double bond, considered to be more reactive, intact, leading to the formation of mono addition-elimination products rather than bis attack at both the reactive centres, even when the reaction was carried out with two moles of cyanoacetic acid. The product viz. benzalcyanoacetic acid and its derivatives were screened for their fungitoxicity against five pathogenic fungi.

Synthetic Utility of N-Sulfonylimines

Analogous to carbon-carbon and carbon-oxygen double bonds, carbon-nitrogen double bond has been an active site of study in recent times. The reactivity of the carbon-nitrogen double bond lies in between that of the carbonyl and olefinic functions. The carbon-nitrogen double bond has an additional lone pair of electrons which leads to its distinctive properties from carbon-carbon double bond.

Chiral Lewis base promoted trichlorosilane reduction of ketimines. An enantioselective organocatalytic synthesis of chiral amines

The reduction of the carbon–nitrogen double bond is an important transformation. Here we report our studies on a family of chiral organic catalysts able to promote the stereoselective reduction of ketimines with trichlorosilane. The very cheap, metal-free catalysts were easily prepared in one step from commercially available products, namely a chiral aminoalcohol and picolinic acid derivatives. The catalyst structure was extensively modified in a study that allowed to identify an extremely active species, able to promote the reduction on a large variety of substrates with high efficiency (up to 95% ee). A three component methodology has been also developed, where the enantiomerically enriched amine was isolated after performing the reaction by mixing a ketone and an amine in the presence of trichlorosilane and the catalyst. Its synthetic potentiality was demonstrated by employing the present metal-free catalytic procedure in the preparation of ( S)-metolachlor, a potent and widely used herbicide.

First synthesis of 1,3-oxaselenepanes

The first synthesis of 1,3-oxaselenepane derivatives by the reaction of aryl isoselenocyanates with 4-bromobutanol in the presence of sodium hydride in THF as a one-pot reaction is described. The Z/E isomerism for the exocyclic carbon–nitrogen double bond in the selenium heterocycles was observed for the first time.

Synthesis, characterization and protein binding properties of supported dendrons

Novel benzylether type aldehyde and acetal terminated dendrons were synthesized and attached to a silica gel support; a linear spacer was also introduced as a control material. The supported dendritic compounds were mainly characterized by solid state 13C CPMAS NMR, elemental analysis and X-ray photoelectron spectroscopy (XPS) and the presence of free aldehydes was determined by the purpald test. Bovine serum albumin (BSA) protein was coupled to the dendronized support by imine bond formation, followed by irreversible reduction of the carbon–nitrogen double bond. A significant positive dendritic effect was observed on the antibody binding capacity of immobilised BSA as measured by fluorescence immunoassay (FIA).

Anodic Oxidation of Ketone Allylhydrazones into the Corresponding Azines

Several ketone allylhydrazones were electrochemically oxidized in methanol in the presence of sodium methoxide and potassium iodide to afford the corresponding azines. The electro-oxidation involves formation of a new carbon–nitrogen double bond between an allylic carbon atom and the nitrogen atom of a hydrazone to afford a conjugated system. Optimal yields were obtained when 0.5 equivalents of sodium methoxide and a catalytic amount of potassium iodide were used as the supporting electrolyte at room temperature. Presumably, the electro-oxidation involves a two-electron oxidation process where the iodide ion functions as electron carrier.

Direct conversion of 1-deoxy-1-nitroalditols to methyl glycofuranosides

Treatment of the sodium nitronate forms of 1-deoxy-1-nitrohexitols with methanolic sulfuric or hydrochloric acid at −30 °C leads to their regiospecific conversion to the corresponding methyl glycofuranosides. The reaction exhibits more pronounced stereoselectivity for 1-deoxy-1-nitroalditols with the 2,3- erythro configuration than with the 2,3- threo substrates and cis methyl glycofuranosides are the major products. The observed stereoselectivity indicates the lysis of the protonated aci-nitro form which is a two-step process consisting of nucleophilic addition to the protonated carbon–nitrogen double bond followed by the bimolecular nucleophilic substitution of the nitrogen-containing residue.

Novel Dehydrogenase Catalyzes Oxidative Hydrolysis of Carbon-Nitrogen Double Bonds for Hydrazone Degradation

Hydrazines and their derivatives are versatile artificial and natural compounds that are metabolized by elusive biological systems. Here we identified microorganisms that assimilate hydrazones and isolated the yeast, Candida palmioleophila MK883. When cultured with adipic acid bis(ethylidene hydrazide) as the sole source of carbon, C. palmioleophila MK883 degraded hydrazones and accumulated adipic acid dihydrazide. Cytosolic NAD+- or NADP+-dependent hydrazone dehydrogenase (Hdh) activity was detectable under these conditions. The production of Hdh was inducible by adipic acid bis(ethylidene hydrazide) and the hydrazone, varelic acid ethylidene hydrazide, under the control of carbon catabolite repression. Purified Hdh oxidized and hydrated the C=N double bond of acetaldehyde hydrazones by reducing NAD+ or NADP+ to produce relevant hydrazides and acetate, the latter of which the yeast assimilated. The deduced amino acid sequence revealed that Hdh belongs to the aldehyde dehydrogenase (Aldh) superfamily. Kinetic and mutagenesis studies showed that Hdh formed a ternary complex with the substrates and that conserved Cys is essential for the activity. The mechanism of Hdh is similar to that of Aldh, except that it catalyzed oxidative hydrolysis of hydrazones that requires adding a water molecule to the reaction catalyzed by conventional Aldh. Surprisingly, both Hdh and Aldh from baker's yeast (Ald4p) catalyzed the Hdh reaction as well as aldehyde oxidation. Our findings are unique in that we discovered a biological mechanism for hydrazone utilization and a novel function of proteins in the Aldh family that act on C=N compounds.