With a miniaturized (3 microL volume) fiber-optics based system for on-line measurement by UV/Vis spectroscopy, the reaction rate constants (at different pressures) and the activation volumes (deltaV(not =)) were determined for a nucleophilic aromatic substitution and an aza Diels-Alder reaction in a capillary microreactor.

A one-pot synthesis of anilines and nitrosobenzenes from phenols has been developed using an ipso-oxidative aromatic substitution ((i)SOAr) process. The products are obtained in good yields under mild and metal-free conditions. The leaving group effect on reactions that proceed through mixed quionone monoketals has also been investigated and a predictive model has been established.

An efficient solvent free reaction of 1-chloro-2-nitrobenzene with anilines to give N-substituted nitro anilines by nucleophilic aromatic substitution in good to excellent yields has been described. The effect of different salts on the reaction has also been studied.

Aromatic substitution of 1-fluoro-2,4-dinitrobenzene has been shown to proceed more rapidly in an ionic liquid than in ethanol, primarily due to entropic, rather than enthalpic, effects. By using molecular dynamics simulations, an anion-pi interaction appears to contribute to strong ordering within the starting material complex that accounts for the relative differences in the S(N)Ar k.

The first total synthesis of pterocellin A (1) was achieved in 10 linear steps from commercially available kojic acid (6) and 2-bromo-3-pyridinol (11) in a convergent sequence. The key constructive steps are a directed lithiation to couple two pyridines and an intramolecular nucleophilic aromatic substitution to form 1. [structure: see text]

Several specific synthetic protocols were developed for the preparation from cyanuric chloride of a range of symmetric and non-symmetric di- and tri-substituted 1,3,5-triazines containing alkyl, aromatic, hindered, chiral and achiral hydroxyalkyl, ester and imidazole groups via sequential nucleophilic substitution of the C-Cl bond by C-O, C-N and C-S bonds.

Three new strobilurins F, G and H, antibiotics with antifungal activity, were isolated from cultures of Bolinea lutea Sacc. These new compounds differ from previously described analogs in their aromatic substitution. An HPLC method allows complete separation of all the components.

A transition-metal-free phenanthrene synthesis starting from readily accessible ortho-amino-biaryls is presented. The biarylamines are in situ transformed into the corresponding diazonium salts which upon single electron reduction give the corresponding aryl radicals. Addition to an alkyne and subsequent base promoted homolytic aromatic substitution (BHAS) provide phenanthrenes in moderate to g...

Reported here is a palladium catalyzed intramolecular acylcyanation of alkenes using α-iminonitriles. Through this method, highly functionalized indanones are synthesized in moderate to high yields using Pd(PPh3)4, without need for any additional ligands, and a common Lewis acid (ZnCl2). Additionally, the reaction tolerates substitution at various positions on the aromatic ring including electr...

• Biophysical properties of residues: Amino acids differ in size and charge. Some are acidic, some are basic, some have aromatic side chains. Generally, replacement of an amino acid with another amino acid with similar properties is less likely to break the protein or cause a dramatic change in function than replacement with an amino acid with different properties. A substitution matrix should ...