SYNTHESES AND REACTIVITY OF NEW P-H DIBENZOBICYCLIC PHOSPHORANES BEARING HYDROXY-, ALKOXY-, OXO-, AMIDO-, AND DIHYDRIDO-FUNCTIONS AT THE PHOSPHORUS ATOM

Abstract

A series of new dibenzophosphoranes (1-6) bearing uncommon functions such as hydroxy-, alkoxy-, oxo-, amide- and dihydride- attached to the phosphorus atom have been prepared and characterized. The reactivities of the alkoxy derivative 1 and the amide 2 towards alcohols, amines, water and borane were studied mainly by ³¹P NMR. The structure of the diphenoxyamine-bis-phoshorane 4 was established by single crystal X-ray diffraction studies.     

“Vibrational Spectra of Tetrapropylammonium Trichlorozincate (II)”

The IR and Raman spectra of Crystalline Tetrapropylammonium trichlorozincate (II) have been measured at room and liquid nitrogen temperatures. The spectra have been interpreted in terms of halogen bridged structures. The complete coincidence of the IR and Raman bands suggests a symmetry lower than D_2h and rules out any centrosymmetric structure.     

Titanocene(III)‐Catalyzed 6‐exo Versus 7‐endo Cyclizations of Epoxypolyprenes: Efficient Control and Synthesis of Versatile Terpenic Building Blocks

In this article, a complete study on the selectivity of titanocene(III) cyclization of epoxypolyprenes is presented. The requirements for the formation of six‐ or seven‐membered rings during these cyclizations are determined, taking into account the different substitution pattern in the epoxypolyprene precursor. Thus, a complete selectivity to 6‐exo or 7‐endo cyclization process has been achieved, yielding mono‐, bi‐, and even tricyclic compounds, constituting a new and efficient access to this type of derivative. Additionally, this procedure opens the possibility to prepare excellent building blocks for the synthesis of polycyclic compounds with a trisubstituted oxygenated function, which is present in several natural terpenes.     

Classification of semigroups of linear fractional maps in the unit ball

We give a complete classification up to conjugation of continuous semigroups of linear fractional self-maps of the unit ball.     

The hydroxyacetone (CH3COCH2(OH)) torsional potential and isomerization: A theoretical study

In this work we explore the torsional potentials for hydroxyacetone using second order Møller‐Plesset (MP2) and coupled‐cluster (CCSD(T)) ab initio theoretical methods. We have calculated these potential energy surfaces as a function of single OH rotation, and simultaneous OH and methyl rotation. The results indicate that the low energy isomers coupled to the reduced barrier to methyl rotation can lead to several rotamers for this species to form. The values are compared to experimental quantities and implications for astrobiological research are also addressed. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008