Oee-Sook Park

A CONVENIENT ONE-POT SYNTHESIS OF 4-HYDROXYCOUMARIN, 4-HYDROXYTHIOCOUMARIN, AND 4-HYDROXYQUINOLIN-2(1H)-ONE

An improved one-pot synthesis of 4-hydroxycoumarin, 4-hydroxythiocoumarin, and 4-hydroxyquinolin-2(1H)-one from 2-hydroxyacetophenone, 2-mercaptoacetophenone, and 2-aminoacetophenone, respectively, is described. The synthetic strategies involve the acylation and internal ring cyclization. This method is readily amenable to large-scale synthesis of 4-hydroxycoumarin, 4-hydroxythiocoumarin, and 4-hydroxyquinolin-2(1H)-one derivatives in high yields.

Simple and Cost Effective Syntheses of 4-Hydroxycoumarin

Abstract Two simple and inexpensive methods for the preparation of 4-hydroxycoumarin from aspirin are described, which should be readily amenable to large scale synthesis.

A HIGHLY PRACTICAL ROUTE TO 2-METHYLCHROMONES FROM 2-ACETOXYBENZOIC ACIDS

2-Methylchromones were accessed via a keto ester condensation on 2-acetoxybenzoyl chloride, followed by cyclization and decarboxylation. No column chromatography was required in the process.

PREPARATION OF 2-CHLOROPYRIDINE

Regiospecific chlorination of pyridine-N-oxide to give 2-chloropyridine was achieved in 90% yield with 99.2% selectivity by treatment with phosphorus oxychloride in the presence of a stoichiometric amount of triethylamine. Other chlorinating agents such as sulfuryl chloride, p-toluenesulfonyl chloride, trichloroacetyl chloride, benzenesulfonyl chloride and methanesulfonyl chloride produced 2-chloropyridine also under these conditions, albeit in moderate yield.

Efficient and Practical Syntheses of Benzothiopyran Derivatives

Abstract Concise and inexpensive methods for the preparation of 4-hydroxy-1-thiocoumarin and 2-methylthiochromone from 2-mercaptobenzoic acid are described, which should be readily amenable to large scale synthesis.

Efficient synthesis of (′)-juglomycin A

Abstract (±)‐Juglomycin A has been synthesized in 8 steps from 1‐hydroxy‐5‐methoxynaphthalene.

Synthesis and antibacterial activity of 2-substituted 6-fluoro-1,4-dihydro-4-oxo-3-quinolinecarboxylic acids

A series of 2-substituted 6-fluoro-1,4-dihydro-4-oxo-3-quinolinecarboxylic acids was prepared and evaluated for antibacterial activity. The 6-fluoro-2-methyl-1-prenyl-1,4-dihydro-7-(3,5-dimethylpiperazinyl)-4-oxo-3-quinolinecarboxylic acid (14f) exhibited the most potent antibacterial activity against gram-positive bacteria among the total 32 derivatives. The synthetic strategies involve the use of well known keto ester condensation of benzoyl chloride and reductive cyclization of intermediates (4a-d) to afford 4-hydroxy-1,2-dihydro-2-oxo-quinoline derivatives (5a,b) or 1-hydroxy-1,4-dihydro-4-oxo-quinoline derivatives (6a,b).

Simple Synthesis of Eudesmin through Oxidative Coupling of Carbanions and Reductive Catalytic Hydrogenation of Diketo Diester

Abstract A simple synthesis of eudesmin (1) is described. The key fragments were diol 13, dicarbethoxyethane 4, and diketo diester 5, which were prepared via reductive catalytic hydrogenation and oxidative intermolecular coupling of carbanions. This method is useful to generate the core skeleton of an endo–endo furofuran ring.