Palladium-catalyzed direct coupling reaction of propargylic alcohols with arylboronic acids

The direct coupling of propargylic alcohols with arylboronic acids has been achieved using palladium catalyst. Various propargylic alcohols and arylboronic acids can be coupled to afford the corresponding allenic and propargylic arenes, which are selectively produced depending on the substituent on the propargylic alcohol, respectively.     

Rationally functionalized deltahedral zintl ions: synthesis and characterization of [Ge9-ER3]3-, [R3E-Ge9-ER3]2-, and [R3E-Ge9-Ge9-ER3]4- (E=Ge, Sn; R=Me, Ph)

Six new derivatized deltahedral Zintl ions have been synthesized by reactions between the known Zintl ions Ge(9) (n-) with the halides R(3)EX and/or the corresponding anions R(3)E(-) for E=Ge or Sn. This rational approach is based on our previous discovery that these derivatization reactions are based on nucleophilic addition to the clusters. All species were structurally characterized as their salts with potassium countercations sequestered in 2,2,2-crypt or [18]crown-6 ether. The tin-containing anions were characterized also in solutions by (119)Sn NMR spectroscopy. The reaction types for such substitutions and the structures of the new anions are discussed.     

聚合物支载相转移催化剂的研究2.聚苯乙烯支载苯并-15-冠-5-与无环冠醚

本文报道了三种聚苯乙烯支载苯并-15-冠-5与两种聚苯乙烯支载无环冠醚的合成,并研究了它们对K~+与Na~+的络合性能与相转移催化性能。     

Synthesis and structure of 5,6,7,12-tetrahydrodibenz[c,f][1,5]azabismocines

Hypervalent organobismuth compounds, 6-tert-butyl-5,6,7,12-tetrahydrodibenz[c,f][1,5]azabismocines, with 13 different substituents on the bismuth atom including halogens, alkyl, alkenyl, alkynyl, aryl, or phenylthio groups have been synthesized. A key compound, 12-chloro-6-tert-butyl-5,6,7,12-tetrahydrodibenz[c,f][1,5]azabismocine, which is a precursor for other azabismocines, has been synthesized by two different procedures; one is based on Akiba’s method using 2-bromobenzylbromide as one of the starting materials and the other is a newly developed one using a cheaper starting material, 2-chlorobenzyl chloride. The structures of 12 new bismuth compounds were determined by X-ray diffraction. The eight-membered tetrahydroazabismocine ring has proved to be highly flexible and the hypervalent Bi-N bond distances vary ranging from 2.568(3) to 2.896(5) Å, depending on the electronic nature of the substituents on the bismuth atom. The Bi-N bond distances have good linear relationship against Hammett’s σ_m constants.     

桥联双（甲巯咪唑）化合物的合成和配位性能

研究了桥联双(甲巯咪唑)化合物(Ⅰ_a—Ⅳ_a、Ⅰ_b)的合成和配位性能。UV谱显示Ⅰ_a—Ⅳ_a与UO_2~(2+)离子(硬酸)配位,溶液中形成3:1的配合物。Ⅰ_b与Hg~(2+)、Au~(3+)离子(软酸)配位形成2:1的配合物,用CNDO/2方法计算了各配体分子中原子净电荷密度和HOMO、LUMO能量。     

Diels-Alder reactions of highly pyramidalized tricyclo[3.3.0.0]oct-1(5)-ene derivatives: further chemistry of pentacyclo[6.4.0.0.0.0]dodeca-5,8,11-triene

A study of the trapping of highly pyramidalized tricyclo[3.3.0.0^3,7]oct-1(5)-ene derivatives (generated from a 1,2-diiodo precursor on reaction with t-BuLi, 0.45% sodium amalgam and molten sodium) with different dienes (11,12-dimethylene-9,10-dihydro-9,10-ethanoanthracene, 1,3-diphenylisobenzofuran, 2,5-dimethylfuran and furan) is presented. Byproducts from the trapping of pentacyclo[6.4.0.0^2,10.0^3,7.0^4,9]dodeca-5,8,11-triene with 1,3-diphenylisobenzofuran have been synthesized and fully characterized, including an X-ray diffraction analysis. Also, the above triene has been cross coupled with 3,7-dimethyltricyclo[3.3.0.0^3,7]oct-1(5)ene to give a tetrasecododecahedratetraene derivative.     

Improved third-order Møller-Plesset perturbation theory

Based on a partitioning of the total correlation energy into contributions from parallel‐ and antiparallel‐spin pairs of electrons, a modified third‐order Møller–Plesset (MP) perturbation theory is developed. The method, termed SCS–MP3 (SCS for spin‐component‐scaled) continues previous work on an improved version of MP2 (S. Grimme, J Chem Phys 2003, 118, 9095). A benchmark set of 32 isogyric reaction energies, 11 atomization energies, and 11 stretched geometries is used to assess to performance of the model in comparison to the standard quantum chemical approaches MP2, MP3, and QCISD(T). It is found, that the new method performs significantly better than usual MP2/MP3 and even outperforms the more costly QCISD method. Opposite to the usual MP series, the SCS third‐order correction uniformly improves the results. Dramatic enhancements are especially observed for the more difficult atomization energies, some of the stretched geometries, and reaction and ionization energies involving transition metal compounds where the method seems to be competitive or even superior to the widely used density functional approaches. Further tests performed for other complex systems (biradicals, C₂₀ isomers, transition states) demonstrate that the SCS–MP3 model yields often results of QCISD(T) accuracy. The uniformity with which the new approach improves for very different correlation problems indicates significant robustness, and suggests it as a valuable quantum chemical method of general use. © 2003 Wiley Periodicals, Inc. J Comput Chem 24: 1529–1537, 2003     

Efficient Chemoselective Oxidation of Phenylmethanols to Aldehydes with Iodosobenzene

Summary. Primary phenylmethanols are selectively and efficiently oxidized to the corresponding aldehydes by the system C₆H₅IO/(C₆H₅)₄PBr/CH₂Cl₂, T = 298 K under aerobic conditions. The use of the relatively stable iodosobenzene, an iodine(III) compound, in place of the usually employed and potentially explosive iodine(V) reagents, the easy work-up procedure, and the facile recycling of solvent and oxidant provides a convenient and environmentally benign oxidation method.     

Diborane (4) derivatives via coupling of amine monobromocyanoboranes: Study of the bromination of amine cyanoborane and molecular structures of the amine dibromocyanoboranes

The first examples of diborane (4) compounds derived from amine cyanoboranes are described. A series of monobromo derivatives of amine cyanoboranes (A:BHBrCN), and dibromo derivatives (A:BBr₂CN), 1-7, were prepared. Lithiation of the monobromo derivative of trimethylamine cyanoborane, using n-BuLi, did not produce the C-lithiated intermediate Li⁺ [CH₂NMe₂BHBrCN]⁻, but instead the B-lithiated intermediate Li⁺ [Me₃NBHCN]⁻, was obtained. This intermediate, when allowed to react for 16 h, coupled with the un-lithiated trimethylamine monobromocyanoborane (Me₃NBHBrCN) and resulted in diborane (4) derivative formation as the 2LiBr complex. The same result was obtained when one equiv of the trimethylamine monobromocyanoborane was added to the reaction mixture 1 h after lithiation. Following the same procedure, novel diborane (4) derivatives of amine cyanoboranes were successfully obtained, 8-11, as their 2LiBr complexes from the monobromo derivatives of the corresponding amine cyanoboranes. Molecular structures of the trimethylamine dibromocyanoborane, 6, and the triethylamine dibromocyanoborane, 7, were determined using X-ray crystallography.     

Quantum chemical study of alternating N/B and N/C π bonds in (un)charged even‐membered 4n and 4n+2 cyclic systems and their related open systems

With semi‐empirical MO and ab initio calculations at different levels, we investigated the π conjugation of alternating X? Y bonds with X? Y for N/B and N/C combinations in an open and cyclic arrangement. Although the intrinsic symmetry is lost for the acyclic even‐membered compounds, the alternation is still reflected in its geometry and electron‐density transfer. For the cyclic π compounds, we focused our attention on borazine N₃B₃H₆ (D_3h symmetry), which is isoelectronic with benzene (D_6h symmetry). Specific attention is given to the electrophilic behavior of borazine with respect to CH and SiMe. The dynamics based on the results of FT‐ICR mass spectrometry was studied in more detail. In addition, the results of the cyclic systems with 4n and 4n+2 π electrons concerning their geometries are compared with the corresponding carbon compounds. Attention is also given to the dication of borazine, because of the corresponding triplet ground state of the benzene dication. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005