Cyclisation reactions of alkenyl β-ketoesters involving a novel phenylseleno group migration

A number of alkenyl-substituted α-phenylseleno β-ketoesters can be cyclised in the presence of acidic catalysts in which a novel migration of phenylseleno moiety occurs.     

Phosphonium salts and phosphoranes—VI: 31P NMR spectra of acylmethylenephosphoranes

The ³¹P NMR spectra of 36 acylmethylenephosphoranes have been measured and the chemical shifts have been interpreted in terms of steric interactions and the resonance stabilization of the ylides. It is proposed that the observed solvent shift effects are best accounted for by a change in the resonance stabilization and not, as previously suggested, by a change in the conformational equilibrium position. The inductive electron-withdrawing interaction of α-aryl groups leads to a deshielding of the phosphorus nucleus, whilst the deshielding effect produced by α-acyl substituents can be rationalised in terms of a combination of the mesomeric and inductive interactions. Syntheses of 21 new phosphoranes are described.     

Selective Ir-catalysed borylation of polycyclic aromatic hydrocarbons: structures of naphthalene-2,6-bis(boronate), pyrene-2,7-bis(boronate) and perylene-2,5,8,11-tetra(boronate) esters

The selectivity of the iridium boryl complex-catalysed reaction of pyrene and perylene with B2(pin)2 (pin = OCMe2CMe2O) has been employed in the synthesis of D(2h)-symmetry pyrene-2,7-(Bpin)2 and D(4h)-symmetry perylene-2,5,8,11-(Bpin)4 providing direct borylation of positions which are otherwise difficult to derivatise.     

Fourier-transform infrared spectrum of aspartate hydroxo-aqua nickel (II) complex and DFT-B3LYP/3-21G and 6-311G structural and vibrational calculations

Aspartate hydroxo-aqua nickel (II) complex was synthesized and the structural analysis was carried out through the following methods: determination of the C, N, O and H contents, thermogravimetry and infrared spectrum. Several hypothetic structures were calculated by means of DFT: B3LYP/3-21G and B3LYP/6-311G quantum mechanical method. For [Ni(Asp)(OH)(H(2)O)] we have obtained the minimum of energy and no imaginary frequencies in the calculated infrared spectrum. Moreover, the experimental FT-infrared spectrum shows that the two N-H stretching follow the Bellamy-Williams relation proposed for primary amines. Coordination water bands were also observed in the infrared spectrum. For reasons of accomplishment, the Fourier transforms infrared and Raman spectra of acid aspartic were also discussed.     

A non-MRA C^r Frame Wavelet with Rapid Decay

A generalized filter construction is used to build an example of a non-MRA normalized tight frame wavelet for dilation by 2 in . This example has the same multiplicity function as the Journé wavelet, yet has a Fourier transform and can be made to be for any fixed postive integer . L. Baggett and P. Jorgensen were supported by a US–NSF Focused Research Group (FRG) grant.