Likai Xia

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.

An Efficient and Rapid Synthetic Route to Biologically Interesting Pyranochalcone Natural Products

An efficient and concise total synthesis of naturally occurring pyranochalcones was achieved from readily available 2,4-dihydroxyacetophenone and 2,4-dihydroxy-6-methoxyacetophenone. The key steps in the synthetic strategy were ethylenediamine diacetate-catalyzed benzopyran formation and aldol 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.

Regioselective synthesis of novel and diverse naphtho[1,2-b]furan-3-carboxamides and benzofuran-3-carboxamides by cascade formal [3 + 2] cycloaddition

A novel and efficient In(OTf)3-catalyzed cascade formal [3 + 2] cycloaddition of 1,4-naphthoquinones or benzoquinones with β-ketoamides was developed to provide naphtho[1,2-b]furan-3-carboxamides and benzofuran-3-carboxamides. This methodology has broad substrate scope that can afford novel and diverse naphtho[1,2-b]furan-3-carboxamides and benzofuran-3-carboxamides with high regioselectivity in good to excellent yields. Furthermore, this methodology is expected to be applicable to the synthesis of biologically-active complex molecules bearing naphtho[1,2-b]furan-3-carboxamides and benzofuran-3-carboxbenzamides.

A green synthetic approach to synthesizing diverse 2-pyridones for their exceptional UV shielding functions

An efficient green synthesis of a wide range of N-nonsubstituted 2-pyridones via thermal multicomponent reactions of 4-oxo-4H-chromene-3-carbaldehydes with malonates and ammonium acetate under catalyst- and solvent-free conditions is described. This reaction proceeds through domino Knoevenagel condensation/Michael addition/ring opening/ring closure reactions. This protocol has several advantages, such as commercial availability, low toxicity, ease of handling, and environmental benignity. The potential application of the synthesized compounds as UV protecting materials was also evaluated.

Synthesis of novel and diverse naphtho[1,2-b]furans by phosphine-catalyzed [3+2] annulation of activated 1,4-naphthoquinones and acetylenecarboxylates

A new phosphine-catalyzed [3+2] annulation reaction between activated 1,4-naphthoquinones and acetylenecarboxylates is described. This reaction provides a facile and efficient route to a variety of biologically promising and novel naphtho[1,2-

Straightforward synthesis of diverse dipyrazolylmethane derivatives and their application for fluorescence sensing of Cu2+ ions

b

Regioselective Synthesis of Highly Functionalized Furans Through the RuII‐Catalyzed [3+2] Cycloaddition of Diazodicarbonyl Compounds

b]furans. This devised method provides a first example for the synthesis of diverse naphtho[1,2-