Palladium-catalyzed air-based oxidative coupling of arylboronic acids with H-phosphine oxides leading to aryl phosphine oxides

We present a novel and highly efficient methodology that allows for the construction of C-P bonds via the palladium-catalyzed air-based oxidative coupling of various commercially available arylboronic acids with easily oxidized H-phosphine oxides leading to valuable aryl phosphine oxides, particularly triarylphosphine oxides, with the use of air as the green oxidant, broad substrate applicability and good to excellent yields. The described catalytic system should be an efficient complement to the Chan-Lam type reaction and be useful in synthetic programs. This journal is ? the Partner Organisations 2014

Copper-catalyzed synthesis of α-hydroxy phosphonates from H-phosphonates and alcohols or ethers

Easy PC: α-Hydroxy phosphonates were synthesized by copper/tert-butyl hydroperoxide (TBHP)-catalyzed oxidative addition reactions of H-phosphonates with alcohols or ethers. Diverse α-hydroxy phosphonates were obtained from substituted benzyl alcohols or alkyl alcohols and alkyl ethers in moderate to good yields. Copyright ? 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Synthesis of flame-retardant phosphaphenanthrene derivatives with high phosphorus contents

Two novel types of phosphate derivatives of phosphaphenanthrene with a high phosphorus content were prepared by phosphorylation reaction between either 2-(6-oxido-6H-dibenz?c,e??1,2?oxaphosphorin-6-yl)-methanol (ODOPM) or 2-(6-oxido-6H-dibenz?c,e??1,2.oxaphosphorin-6-yl)-1,4-benzenediol (ODOPB) and dialkyl phosphoryl chloride. The structures of all compounds were characterised by 1H NMR, 13C NMR, 31P NMR, Fourier transform infrared spectroscopy, and high-resolution mass spectrometry. The thermal stability of representative compounds was determined by thermal gravimetric analysis and differential scanning calorimetry. The results showed that the compounds have excellent resistance to oxidation, high thermal stability with an onset decomposition temperature above 200°C, and a high char yield over 25 %, owing to the high P content. The representative compound was added to conventional electrolytes of lithium-ion batteries as flame retardant additive, and the self-extinguishing time and ionic conductivity were measured. The result showed that the compounds have effective flame retardant properties. ? CSIRO 2014

Mechanistic insight into the copper-catalyzed phosphorylation of terminal alkynes: A combined theoretical and experimental study

The reaction mechanism of copper-catalyzed phosphorylation of terminal alkynes under different conditions has been investigated experimentally and theoretically. The important role of dioxygen has been elucidated, including the formation of η1-superoxocopper(II), η2- superoxocopper(III), μ-η2:η2-peroxodicopper(II) , and bis(μ-oxo)dicopper(III) complexes. More importantly, the proton transfer from the dialkyl phosphonate (in the form of phosphite) to the bridging oxygen atom entails the migration of the deprotonated phosphonate to the terminal alkyne, leading to the formation of a C-P bond with an activation barrier of only 1.8 kcal/mol. In addition, a particularly stable six-centered dicopper(I) species is formed with the migration of both of the Ph 2P(O) groups from the copper atoms to the oxygen atoms of the bis(μ-oxo) bridge, explaining the experimental observation that secondary phosphine oxides can be oxidized to the phosphinic acids. Thus, the diphenylphosphine oxide was added to the reaction mixture dropwise to minimize the concentration during the reaction course. Gratifyingly, the coupling product was generated almost quantitatively when the reaction was completed. ? 2014 American Chemical Society

Novel high phosphorus content phosphaphenanthrene-based efficient flame retardant additives for lithium-ion battery

The novel phosphate derivatives of phosphaphenanthrene with high-density phosphorus were synthesized and used as flame retardant additives for Li-ion batteries. The structures of compounds were characterized by 1H NMR, 13C NMR, 31P NMR, FT-IR, and HR-MS. The excellent thermal stability of compounds was ascertained by thermogravimetric analysis and differential scanning calorimetry. The compounds were added to conventional electrolytes as flame retardant additives and evaluated their ionic conductivity, electrochemical stability, self-extinguishing properties, and combustion performance. The results showed that the compound containing higher phosphorus content has efficient flame retardant properties. ? 2014 Akade′miai Kiado′, Budapest, Hungary

Synthesis of substituted mono- and diindole C-nucleoside analogues from sugar terminal alkynes by sequential sonogashira/heteroannulation reaction

The synthesis of substituted mono- and diindole C-nucleoside analogues has been achieved in good to excellent yields by sequential Sonogashira coupling/NaAuCl4-catalyzed heteroannulation reactions of substituted 2-iodoanilines with various sugar terminal alkynes in one pot. The method is general, mild, and efficient and suitable for a wide range of sugar substrates, and 42 examples are given. The amino group of the substituted 2-iodoanilines is unprotected. The sugar terminal alkynes include furanosides, pyranosides, and acyclic glycosides with free hydroxyl groups, sensitive functional subtituents, and various protecting groups having different steric hindrance. (Chemical Equation Presented). ? 2014 American Chemical Society

Mn(OAc)3-mediated synthesis of β-hydroxyphosphonates from P(O)-H compounds and alkenes

A new and general method for the synthesis of β-hydroxy phosphonates has been achieved through Mn(OAc)3-mediated radical oxidative phosphonation of alkenes with H-phosphonates and H-phosphine oxide. The starting materials of P(O)-H compounds and alkenes are stable and cheap. Mn(OAc)3 can be readily prepared from Mn(OAc)2 in the laboratory. This method can be easily adapted to large-scale preparations. This journal is ? the Partner Organisations 2014

Palladium-catalyzed Suzuki cross-coupling of arylhydrazines via C-N bond cleavage

The first example of Pd-catalyzed Suzuki cross-coupling of readily available arylhydrazines with arylboronic acids via C-N bond cleavage was developed under air, affording various biaryl compounds with broad substrate applicability and moderate to good yields. Moreover, the rigorous exclusion of air/moisture is not required in these transformations. Thus, the protocol represents a simple and efficient procedure to access biaryl compounds. ? 2014 American Chemical Society

Cs2CO3-promoted one-pot synthesis of alkynylphosphonates, -phosphinates, and -phosphine oxides

A novel and efficient Cs2CO3-promoted phosphorylation or phosphinylation of various 1,1-dibromo-1-alkenes with readily available trialkyl phosphites, ethyl diphenylphosphinite, or diethyl phenylphosphonite has been developed under metal-free conditions, providing a practical and powerful tool for one-pot synthesis of valuable alkynylphosphonates, -phosphinates, and -phosphine oxides in good to excellent yields. ? 2014 American Chemical Society