2-benzazepines. 5. Synthesis of pyrimido[5,4-d][2]benzazepines and their evaluation as anxiolytic agents

A New Series of Tungstophosphoric Acid-Polymeric Matrix Catalysts: Application in the Green Synthesis of 2-Benzazepines and Analogous Rings

A new series of composite materials (PLMTPA) based on tungstophosphoric acid (TPA) included in a polymeric matrix of polyacrylamide (PLM), with a TPA:PLM ratio of 20/80, 40/60, and 60/40, were synthesized and well characterized by FT-IR, XRD, 31P MAS-NMR, TGA-DSC, and SEM-EDAX. Their acidic and textural properties were determined by potentiometric titration and nitrogen adsorption–desorption isotherms, respectively. Considering 31P MAS-NMR and FT-IR analyses, the main species present in the samples is the [PW12O40]3− anion that, according to XRD results, is highly dispersed in the polymeric matrix or appears as a noncrystalline phase. The thermogravimetric analysis revealed that PLMTPA materials did not undergo any remarkable chemical changes up to 200 °C. Additionally, the PLMTPA materials showed strong acid sites whose number increased with the increment of their TPA content. Finally, PLMTPA materials were used as efficient and recyclable noncorrosive catalysts for the synthesis of 2-benzazepines and related compounds. Good yields (55–88%) and high purity were achieved by a Pictet-Spengler variant reaction between N-aralkylsulfonamides and s-trioxane in soft reaction conditions: low toluene volume, at 70 °C, for 3 h. The described protocol results in a useful and environmentally friendly alternative with operative simplicity. The best catalyst in the optimized reaction conditions, PLMTPA60/40100, was reused six times without appreciable loss of activity.

A convenient approach to 2,4-disubstituted quinazoline-3-oxides using active MnO2 as the oxidant

Using cheap, readily available, and economic active MnO2 as an oxidant, a series of 2,4-disubstituted quinazoline-3-oxides were synthesized in good to excellent yields by oxidation of the corresponding 1,2-dihydroquinazoline-3-oxides under mild conditions. This novel approach is simple and convenient and provides a series of 2,4-disubstituted quinazoline-3-oxides.

3-(Hetero)aryl-4-indolylamino-α-tetralones by diastereoselective internal redox cyclization: an "azaenamine" conjugate addition

(E)-3-(hetero)aryl-1-(2-((E)-(indolin-1-ylimino)methyl)phenyl)prop-2-en-1-ones 1 undergo 6-exo-trig cyclization reactions upon treatment with BF(3)·Me(2)S in dichloromethane at low temperature to give the tetralones 10 in good yield. This cyclization process can be considered to be an intramolecular Michael-type addition which is accompanied by an internal redox reaction as the indoline fragment is oxidized to indole with simultaneous hydrogen shift to nitrogen atom N1 and the α-carbon atom of the Michael system. The reactions at the iminic centers take place via umpolung of the classical carbonyl reactivity. The reaction is diastereoselective and affords exclusively 3,4-disubstituted α-tetralones 10 as trans-diastereomers. According to quantum chemical calculations the reactions take place under kinetic control with the trans-diastereomer being the kinetically favored product as it has the lower activation barrier compared to the cis-diastereomer.

One-pot etherification of purine nucleosides and pyrimidines

A one-pot synthesis of ethers derived from inosine, guanosine, 2'-deoxyguanosine, and pyrimidinones is described. Exposure of the heterocycle to 1H-benzotriazol-1-yloxy-tris(dimethylamino)phosphonium hexafluorophosphate (BOP) and Cs(2)CO(3) produces a reactive intermediate, which is converted to the desired ether by subsequent addition of an appropriate alcohol or phenol and Cs(2)CO(3). Although rapid formation of HMPA from BOP can occur in the presence of an alcohol and base, as demonstrated by the reaction with methanol, under appropriate conditions these heteroaryl ethers can be efficiently synthesized.

Can drug effects on anxiety and convulsions be separated?

The effects of benzodiazepines, barbiturates, a series of novel putative anxiolytic compounds and anxiogenic compounds are reviewed in animal tests of anxiety and on experimentally-induced seizures. It is clear from the data that drug effects on anxiety and convulsions are not always in the same direction; certain compounds are apparently both anxiolytic and proconvulsant, others are anxiogenic and anticonvulsant, others have varied effects depending on the test situation. It is suggested that this work necessitates considerable revision of our traditional concepts of an "anticonvulsant." The extent to which drug-induced anxiety is correlated with weak epileptiform activity in the brain is discussed. Finally, the Discussion considers a number of possible mechanisms that could underlie the separation of drug effects on anxiety and convulsions that is observed.