Sung Hong Kim

Microwave-Assisted Synthesis of Diverse Pyrrolo[3,4-c]quinoline-1,3-diones and Their Antibacterial Activities

With the aim of developing a general and practical method for library production, a novel and efficient two-phase microwave-assisted cascade reaction between isatins and β-ketoamides in [Bmim]BF4/toluene was developed for the synthesis of pyrrolo[3,4-c]quinoline-1,3-diones. The features of this methodology are, the use of microwave-assisted rapid synthesis, mild reaction conditions, high yields, operational simplicity, facile product separation, and recyclability. Furthermore, the antibacterial activities of the pyrrolo[3,4-c]quinoline-1,3-dione derivatives produced were evaluated against Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, and Enterobacter aerogenes) and Gram-positive bacteria (Bacillus cereus and Staphylococcus aureus). These derivatives showed antibacterial activities against Gram-positive strains that were at least equivalent to that against Gram-negative strains. Compound 7{3,5} displayed the most potent antibacterial activity against P. aeruginosa (MIC = 0.5 μg/mL) and greater activity than standard ampicillin (MIC = 1 μg/mL). Compound 7{4,7} exhibited the best inhibitory activity against E. coli and E. aerogenes (MIC = 1 and 0.5 μg/mL), compared with the standard ampicillin (both MICs = 1 μg/mL). The synthesized pyrrolo[3,4-c]quinoline-1,3-diones are expected to be widely used as lead compounds for the development of new antibacterial agents.

Eco-friendly synthesis of diverse and valuable 2-pyridones by catalyst- and solvent-free thermal multicomponent domino reaction

An efficient and highly eco-friendly synthesis of diverse and functionalized 2-pyridone derivatives in good yield via the thermal multicomponent reaction of 4-oxo-4H-chromene-3-carbaldehydes with 1,3-diketoesters and anilines or primary aliphatic amines under catalyst- and solvent-free conditions is described. This reaction proceeds via domino Knoevenagel condensation/Michael addition/ring opening/ring closure reactions.

Synthesis of novel and diverse mollugin analogues and their antibacterial and antioxidant activities

Novel and diverse mollugin analogues (1-12) were synthesized using PhB(OH)2/AcOH-mediated electrocyclization reaction as a key step. The newly synthesized compounds were screened for antioxidant and antibacterial activities. Compounds 1, 2, 5, 6, 8, and 10-12 showed high antioxidant activities in DPPH inhibition (IC50=0.52-1.11 μM) compared with BHT (IC50=9.67 μM). Compounds 3 exhibited potent antibacterial activity against Staphylococcus aureus (KCTC-1916) bacterial strain at 100 μg/mL. Structures of newly synthesized compounds were confirmed by IR, (1)H NMR, (13)C NMR data and high-resolution mass spectrometry.

Rhodium(II)-catalyzed direct sulfenylation of diazooxindoles with disulfides

Rhodium(II)-catalyzed direct sulfenylation of diazooxindoles using disulfides as the sulfenylating agent was developed via intermolecular C–S bond formation. This novel protocol provides a rapid synthetic route to 3-alkylthiooxindoles, 3,3-dialkylthiooxindoles, or 3,3-diarylthiooxindoles in moderate to good yield. The transformation is proposed to proceed through sulfur ylide formation followed by S–S bond cleavage and rearrangement.

Efficient one-pot synthesis of novel and diverse furo[2,3-\(d\)]pyrimidinediones and thioxofuro[2,3-\(d\)]pyrimidineones by the rhodium (II) pivalate-catalyzed reactions of cyclic diazo compounds

The rhodium(II)-catalyzed reactions of cyclic diazo compounds derived from barbituric acid or thiobarbituric acid with arylacetylenes and styrenes were examined. These reactions provide a rapid synthetic route to the preparation of a variety of novel and diverse furo[2,3-

Novel construction of diversely functionalized N-heteroaryl-2-pyridones via copper(II)-catalyzed [3+2+1] annulation

d

Copper-catalyzed [3 + 2 + 1] annulation for functionalized pyridines as potent and dynamic UV absorbers

d]pyrimidine-2,4-diones, 2-thioxodihydrofuro[2,3-