No abstract

Benzoxazolinone derivatives have been found to exhibit various pharmacological properties and 6‐acyl‐2(3H)‐benzoxazolones are considered as key starting materials for the preparation of these compounds. Reported here are the optimal conditions for a regioselective acylation at the 6‐position of the benzoxazolinone ring. A general method leading to the expected products in excellent yields consists in using a mixture of aluminum chloride‐dimethylformamide as catalyst and acid anhydrides or chlorides as acylating agents.

Chalcones featuring an analgesic/anti-inflammatory pharmacophore, i.e., the 2(3H)-benzoxazolone heterocycle, on the one hand, and a radical scavenger moiety, i.e., 2,6-di-t-butylphenol, on the other hand were synthesized by condensation of a ketone 2(3H)-benzoxazolone precursor with 3,5-di-t-butyl-4-hydroxybenzaldehyde. Among the various methods explored (acid homogenous or heterogenous catalysis, base catalysis), heterogenous catalysis conditions using KSF Montmorillonite were found to be the most convenient. The E-geometry of the soobtained chalcones was ascertained both by 1 H and 13 C-nuclear magnetic resonance (NMR) spectroscopy as well as B3LYP/6-31G ** quantum mechanics calculations. Chalcones 1-8 were pharmacologically evaluated in vitro for their ability to prevent human low-density lipoprotein (LDL) copper-induced oxidation using Cu 2? as oxidizing agent. Compound 4 emerged as the most promising agent as it was able to inhibit copper-mediated human LDL oxidation with an activity ten times greater than that of Probucol, a reference antioxidant drug.

No abstract

To study the scope and limitations of the use of complexed species of AlCl 3 in FriedelCrafts reactions, we investigated the acetylation and benzoylation of 2(3H)-benzoxazolone and 3-methyl-2(3H)-benzoxazolone varying the amide complexing agent. We replaced dimethylformamide by N-methylformamide, dimethylacetamide, pyrrolidone, N-methylpyrrolidone, tetramethylurea, and dimethylsulfoxide. However, there was no particular advantage of substituting dimethylformamide by another amide ligand. This can probably be ascribed to the fact that the complex formed between AlCl 3 and the complexing agent becomes too stable. Alternatively, a route using polyphosphoric acid and microwave activation was explored. The major advantage of running the reaction in a microwave oven was that a good yield was reached in a rather short period of time.