The synthesis and structure of 1,3,4-trisubstituted 2,5-dioxopyrrolidines and their behaviour in liquid crystalline systems

To find novel compounds for liquid crystalline mixtures with improved properties, a series of optically active 1,3,4-trisubstituted 2,5-dioxopyrrolidines has been prepared. Their structure was confirmed by IR spectroscopy. The twisting ability of the compounds prepared was studied.     

Useful transformations: From ion-laser interactions to master equations

We show a set of transformations that allow one to obtain analytical solutions in several quantum-optical problems. We start with the ion-laser (time-dependent) interaction, continue with the problem of a slow atom interacting with a quantized field, and end with a master equation that describes the losses. In all cases, it is shown that one may find useful transformations that simplify the problems.     

Variational transition‐state theory study of the atmospheric reaction OH + O3 → HO2 + O2

We report variational transition‐state theory calculations for the OH + O₃→ HO₂ + O₂ reaction based on the recently reported double many‐body expansion potential energy surface for ground‐state HO₄ [Chem Phys Lett 2000, 331, 474]. The barrier height of 1.884 kcal mol^?1 is comparable to the value of 1.77–2.0 kcal mol^?1 suggested by experimental measurements, both much smaller than the value of 2.16–5.11 kcal mol^?1 predicted by previous ab initio calculations. The calculated rate constant shows good agreement with available experimental results and a previous theoretical dynamics prediction, thus implying that the previous ab initio calculations will significantly underestimate the rate constant. Variational and tunneling effects are found to be negligible over the temperature range 100–2000 K. The O₁? O₂ bond is shown to be spectator like during the reactive process, which confirms a previous theoretical dynamics prediction. © 2007 Wiley Periodicals, Inc. 39: 148–153, 2007     

A cascade reaction sequence en route to 7-substituted 2-aminopyrrolo[1,2-a]pyrimidine-4,6-diones and the corresponding acrylic acid derivatives

Reaction of α-bromo ketones with 6-amino-2-methylpyrimidin-4(3H)-one under basic conditions and in the presence of atmospheric oxygen affords novel 7-substituted 2-amino-pyrrolo[1,2-a]pyrimidine-4,6-diones that are readily hydrolyzed to afford the corresponding acrylic acid derivatives. The reaction sequence consists of an initial alkylation, followed by an unexpected condensation, elimination, and oxidation sequence to afford the products. This cascade reaction sequence represents a rapid and unprecedented route to the described small molecules.