Hydroformylation of olefins catalyzed by rhodium complex anchored on clay matrices

Investigations on the catalytic activity of a transient Rh(I) triphenylphosphine complex1 anchored on montmorillonite clay have been carried out with respect to hydroformylation of olefins at 70°C and 60 atm of CO+H₂ (1:1). The analysis has shown that aldehydes and hydrocarbons of the corresponding olefins result under hydroformylation conditions. In limonene, reaction proceeds with double hydroformylation and hydrogenation to give the respective oxo products. The catalytic activities of1 are compared with Wilkinson's Rh^I (H) (CO) (PPh₃)₂ (6) complex in solution under the same hydroformylation conditions.     

An Alternate Synthesis of 4-Hydroxybenzocyclobutene

4-Hydroxybenzocyclobutene was prepared in good yield from the demethylation of 4-methoxybenzocyclobutene with aluminum iodide in acetonitrile.     

High resolution proton magnetic resonance spectroscopy of human brain and liver

Water-suppressed and slice-selective proton spectra of live human brain exhibited several resonances that were tentatively assigned to metabolites such as N-acetylaspartate, glutamate, phosphocreatine and creatine, choline derivatives, and taurine. In the liver spectrum of a healthy volunteer, the major resonance was tentatively assigned to a fatty acyl methylene and the minor resonances to protons in carnitine, taurine, glutamate, and glutamine. In the spectrum of a cancerous liver, resonances in addition to those present in the normal liver were seen. Protein degradation in the liver with cancer was indicated by resonances from urea and from the ring protons in tryptophan, tyrosine, and phenylalanine. Furthermore, increased nucleic acid synthesis was indicated by resonances from nucleotide protons.     

RAPID: Randomized pharmacophore identification for drug design

This paper describes a randomized approach for finding invariants in a set of flexible and chemically distinct ligands (drug molecules) that underlies an integrated software system called RAPID currently under development. An invariant is a collection of features embedded in ³ which is present in one or more of the possible low-energy conformations of each ligand. Such invariants are called pharmacophores and contain the parts of the ligand that are primarily responsible for its binding with a receptor. The identification of pharmacophores is crucial in drug design since frequently the structure of targeted receptor is unknown but a number of molecules that interact with it have been discovered by experiments. In these cases the pharmacophore is used as a template for building more effective drugs. It is expected that our techniques and results will prove useful in other applications such as molecular database screening and comparative molecular field analysis.     

Thermotropic copolyesters. III. Synthesis and characterization of liquid crystal copolyesters containing the bicyclo[2.2.2]octane ring system

A number of thermotropic copolyesters which contain the bicylo[2.2.2]octane ring system have been synthesized. Because of the stiffening effect of the bicyclo[2.2.2]octane group on the chain, the sebacoyl spacer was used to obtain meltable compositions.