Total synthesis of ionophores the monensin BC-rings via permanganate promoted stereospecific oxidative cyclization

Complex tetrahydrofuran 8, containing the elements of the BC-rings of monensin with four chiral centers, and functionalized for further elaboration, is synthesized via permanganate promoted stereospecific oxidative cyclization of an acyclic, achiral 1,5-diene precursor.     

Triphenylphosphine-catalysed conversion of maleic anhydride into acrylate esters

Maleic anhydride has been converted into a range of acrylate esters on treatment with a suitable alcohol using triphenylphosphine as a catalyst.     

A generalized restricted open-shell Fock operator

We reexamine the open shell restricted Hartree-Fock theory and develop Fock-like operators that are quite general and easy to implement on a computer. We present a table of vector coupling coefficients that define this operator for most of the cases that commonly arise. We compare the form of this operator with that suggested by others, and discuss the orbitals obtained by this procedure with respect to the generalised Brillouin's theorem, and the orbital energies with respect to Koopmans' approximation.Dedicated to Professor J. Koutecký on the occasion of his 65th birthday     

Analysis and Implications of Management Uses of Information

It is a prerequisite to a number of management orientated disciplines that a manager's needs for information are defined. An initial stage in being able to adequately define needs is to understand the ways in which information can affect management behaviour. Several ways are suggested in this paper and from these, implications are drawn which are of relevance to designers of information systems.     

An intramolecular Diels-Alder approach to the synthesis of the right hand half of the ionophore antibiotic X-14547A

Starting from ethylbutyrate, an efficient synthesis of the right hand half of the antibiotic X-14547A has been achieved in which the desired five relative chiral centres were created by an intramolecular Diels-Alder reaction.     

Wide-angle neutron scattering studies of mixed crystals of polyethylene and deuteropolyethylene

Wide-angle neutron scattering studies have been made of a series of mixed crystal blends of polyethylene and deuterated polyethylene in the range 0.68 ≤ K = 4πλ^?1 sinθ ≤ 2.02 Å^?1. Recent calculations by Stamm have shown that regularly folded subunits of small numbers (two to ten) of stems should produce an observable modulation of the diffuse scattering pattern of such mixtures in this K range. For both melt- and solution-crystallized blends, no extra signal was observed above the background scattering level. The data are used to place an upper limit (of about four) on the number of stems that could be regularly folded in the (100) and (010) planes for these materials.     

The polarised beam asymmetry in photoproduction of eta mesons from protons at 2.5 GeV and 3.0 GeV

Measurements of the polarised beam asymmetry parameter Σ for eta photoproduction from protons, have been carried out at incident energies of 2.5 GeV and 3.0 GeV, and for various t-values between ?0.2 (GeV/c)² and ?1.2 (GeV/c)². The values of Σ are close to +1 for values of |t| less than 0.7 (GeV/c)², showing that there can be little contribution from unnatural parity exchange in any Regge exchange model of the process, in disagreement with present theories. Differential cross sections for the process werre also measured, and are consistent with those from other experiments.