C-Phosphorylation of Electron-Rich Heterocycles by Trivalent Phosphorus Halides

Abstract

Convenient methods for introducing dihalogenphosphinogroup at of pyrrole and hran rings have been developed. It was found that dibromphosphinogroup migrated from the second to the third position of the N-methylpyrrole. Convenient methods for phosphorylation of N- alkylcarbazole and iminostilbene have been developed.     

C-Phosphorylation of Compounds with the Electron-Rich Double Carbon-Nitrogen Bond

Abstract

C-phosphorylation of N,N-dimethylhydrazones and N,N-dimethyl-N′-arylamidines by phosphorus tribromide was first accomplished. It directs to the formation of novel types of functional P(III) derivatives (1–3)     

C-Thiocarbamoylation of Electron-Rich Heterocycles and Enamines with Amidophosphonium Isothiocyanates

Amidophosphonium isothiocyanates thiocarbamoylate a series of electron-rich heterocycles and enamines at the nucleophilic carbon atom to form phosphazothiocarbonyl compounds. From the most active heterocycles, bis(phosphazothiocarbonyl) derivatives can be obtained.     

Synthesis of Pterocarpan-Type Heterocycles via Oxidative Cycloadditions of Phenols and Electron-Rich Arenes

Oxidation of 4-alkoxyphenols or 4-methoxynaphthol with phenyl iodonium(bis)trifluoroacetate (PIFA) in the presence of electron rich 2H-chromenes or dihydronaphthalenes affords pterocarpans or 5-carbapterocarpans via a formal [3 + 2] cycloaddition process. Acid-catalyzed ionization of quinone dimethylmonoacetal in the presence of 7-methoxy-2H-chromene gave similar results, suggesting a phenoxonium ion intermediate in the oxidative process.     

C-Phosphorylation of Formamidines

C-Phosphorylation of formamidines by trivalent phosphorus halides was researched. Direction of the phosphorylation depends on nature of substituents at the amidine nitrogens. C-Phosphorylated products was shown to be of valuable possibilities to construct phosphoruscontaining heterocycles     

Reactions of Electron-Rich Olefins

Olefins are normally preferentially attacked by electrophiles. This trend is strengthened in enol ethers and enamines, and is particularly pronounced in tetramethoxyethylene and in tetraaminoethylenes. These electron-rich olefins are accordingly also excellent reducing agents. In their reactivity, therefore, they behave as counterparts of tetracyanoethylene. This compound shares with the electron-rich olefins a strong tendency to undergo cycloadditions, the electron-rich olefins adding particularly readily to electrophiles.     

Electrophilic Nitration of Electron-Rich Acetophenones

It is demonstrated that electron-rich disubstituted acetophenones react according to various electrophilic nitration conditions that generally lead to ipso substitution accompanying the conventional reaction. The hydroxy substituent does not seem prone to favor such behaviour.     

Electrophilic Nitration of Electron-Rich Acetophenones

Summary. It is demonstrated that electron-rich disubstituted acetophenones react according to various electrophilic nitration conditions that generally lead to ipso substitution accompanying the conventional reaction. The hydroxy substituent does not seem prone to favor such behaviour.     

Reactions of Electron-Rich Olefins with Proton-Active Compounds

Proton-active substances react with certain electron-rich olefins with cleavage of the central C?C double bond to give compounds that can be formally regarded as insertion products of nucleophilic carbenes. If they satisfy certain structural conditions, they isomerize with β elimination to give open-chain compounds. Both CH-acidic compounds and compounds containing NH or OH groups can undergo this reaction. The mechanisms are discussed, and the importance of the intermediate products to biochemistry (thiamine, tetrahydrofolic acid) is indicated.     

Reactions of Electron-Rich Olefins with Proton-Active Compounds

Abstract: From the reaction of electron-rich olefins, bis(1,3-dimethylbenzimidazolidine-2-ylidene), I, or bis(3-methylbenzothiazolidine-2-ylidene), II with proton active compounds, such as dimethyl phosphite, diethyl phosphite, acetonitrile and benzaldehyde were obtained 2-substituted benzimidazole or benzothiazole derivatives. The compounds synthesized were identified by ¹H, ¹³ C, ³¹P-NMR, mass, FT-IR spectroscopic techniques and micro analysis.     

Microwave-Assisted Aminomethylation of Electron-Rich Compounds Under Solvent-Free Condition

Electron-rich aromatic compounds react with formaldehyde and a secondary amine under solvent-free condition, in the presence of acidic alumina in a commercial microwave oven or at room temperature to produce aminomethylated products in good to excellent yields.     

亲电性对醌二甲烷与富电子烯烃的电荷转移聚合

概述了亲电性对醌二甲烷与富电子烯烃电荷转移聚合的最新进展，着重介绍聚合的一般特征、引发机理、链增长机理，以及单体结构、溶剂对聚合反应的影响。     

Polycationic Redox-Active Cyclophanes with Integrated Electron-Rich Diboron Units

Cationic cyclophanes are widely used in a variety of applications in supramolecular chemistry and materials science. In this work the authors systematically study the integration of electron-rich diboron units with B^II atoms into polycationic cyclophanes with viologen-like electron-acceptor units. They also report a first hexacationic cage-compound in which three diboron units connect two tris(4-pyridyl)triazine acceptor units. Moreover, di- and tetracationic open-structure compounds, in which one diboron unit connects two bispyridyl groups, were synthesized and the properties compared to those of the corresponding closed structures (cyclophanes). The combination of diboron electron-donor units and bi- or oligopyridyl electron-acceptor units leads to intriguing optical and redox properties.     

Pyridinylidenaminophosphines: Facile Access to Highly Electron-Rich Phosphines

Electron-rich tertiary phosphines are valuable species in chemical synthesis. However, their broad application as ligands in catalysis and reagents in stoichiometric reactions is often limited by their costly synthesis. Herein, we report the synthesis and properties of a series of phosphines with 1-alkylpyridin-4-ylidenamino and 1-alkylpyridin-2-ylidenamino substituents that are accessible in a very short and scalable route starting from commercially available aminopyridines and chlorophosphines. The determination of the Tolman electronic parameter (TEP) value reveals that the electron donor ability can be tuned by the substituent pattern at the aminopyridine backbone and it can exceed that of common alkylphosphines and N-heterocyclic carbenes. The potential of the new phosphines as strong nucleophiles in phosphine-mediated transformations is demonstrated by the formation of Lewis base adducts with CO₂ and CS₂. In addition, the coordination chemistry of the new phosphines towards Cu^I, Au^I, and Pd^II metal centers has been explored, and a convenient procedure to introduce the most basic phosphine into metal complexes starting from air-stable phosphonium salt is described.