Reagent-controlled regiodivergent intermolecular cyclization of 2-aminobenzothiazoles with β-ketoesters and β-ketoamides.

Two regiodivergent approaches to intermolecular cyclization of 2-aminobenzothiazoles with β-ketoesters and amides have been developed, controlled by the reagents employed. With the Brønsted base KOBu and CBrCl as radical initiator, benzo[]imidazo[2,1-]thiazoles are synthesized via attack at the α-carbon and keto carbon of the β-ketoester moiety. In contrast, switching to the Lewis acid catalyst, In(OTf), results in the regioselective nucleophilic attack at both carbonyl groups forming benzo[4,5]thiazolo[3,2-]pyrimidin-4-ones instead.

Synthesis of Disubstituted 3-Phenylimidazo[1,2-a]pyridines via a 2-Aminopyridine/CBrCl α-Bromination Shuttle.

A versatile protocol for the synthesis of disubstituted 3-phenylimidazo[1,2-a]pyridines by coupling 2-aminopyridine with phenylacetophenones, phenylacetones, or β-tetralone has been developed. Isolated yields of up to 97% were obtained at 80 °C within 5 h. The 2-aminopyridine/CBrCl system acts as an α-bromination shuttle by transferring Br from CBrCl to the α-carbon of the carbonyl moiety.

Exerting control over the acyloin reaction.

A synthetic method for conducting the acyloin reaction using electron transfer in solution is reported. By linking two esters via their oxygen atoms, it was possible to perform crossed acyloin reactions between two different ester functionalities and display a high degree of preference for an intramolecular coupling process.

The supplementation of levothyroxine among indigenous people in endemic goitre areas: The impact of therapy.

In order to study the effect of levothyroxine in the treatment of endemic goitre, a longitudinal study was conducted among the Aborigines in Lanai Post and Sinderut Post, situated in an iodine-deficient area located in the district of Kuala Lipis, Pahang. All subjects in the treatment group (Lanai Post) were given 100 µg of levothyroxine per day and were followed for 1 1/2 years. A total of 311 subjects were examined at baseline, 323 on the first, 256 on the second, 239 on the third and 184 on the fourth visit following levothyroxine supplementation.