Saegun Kim

Rhodium(III)-Catalyzed C(sp3)–H Alkylation of 8-Methylquinolines with Maleimides

The rhodium(III)-catalyzed cross-coupling reaction of 8-methylquinolines and maleimides is described. In contrast to the C(sp(2))-H functionalization, a first catalytic functionalization of sp(3) C-H bonds with maleimides is reported. This protocol provides a facile access to various succinimide scaffolds on 8-methylquinolines via a direct C-H cleavage approach.

Synthesis and Anti-inflammatory Evaluation of 2-Aminobenzaldehydes via Ir(III)-Catalyzed C–H Amidation of Aldimines with Acyl Azides

The aldimine-directed C-H amidation of various arenes with N-acyl azides as amidation surrogates under cationic iridium(III) catalysis is described. This transformation efficiently provides a range of 2-aminobenzaldehyde derivatives with excellent site selectivity and functional group compatibility. The resulting 2-aminobenzaldehyde framework provides facile access to a range of biologically interesting heterocycles. In addition, all synthetic compounds were screened for anti-inflammatory activity against interleukin-1β (IL-1β) and tumor necrosis factor alpha (TNF-α) with lipopolysaccharide (LPS)-induced RAW264.7 cells. Generally, a range of ortho-amidated benzaldehydes displayed promising inhibitory activity against IL-1β and TNF-α compared to dexamethasone as a positive control. Notably, compounds (3ae and 4ac) were found to exhibit potent anti-inflammatory activity stronger than that of dexamethasone.

Synthesis of (2H)-Indazoles through Rh(III)-Catalyzed Annulation Reaction of Azobenzenes with Sulfoxonium Ylides

The rhodium(III)-catalyzed C-H functionalization followed by intramolecular annulation reactions between azobenzenes and sulfoxonium ylides is described. This protocol leads to the efficient formation of 3-acyl (2 H)-indazoles with a range of substrate scope. A high level of chemoselectivity and functional group tolerance of this transformation were also observed.

Dual Role of Anthranils as Amination and Transient Directing Group Sources: Synthesis of 2-Acyl Acridines

The transient directing group promoted C(sp2)-H functionalization of benzaldehydes with anthranils by a cationic rhodium(III) catalyst is described. Notably, anthranils have been used as both transient directing groups and amination sources to afford 2-acyl acridines through direct C-H amination followed by acid-mediated cyclization. A range of substrate scopes and functional group tolerance were observed.

One-pot Synthesis of 2-Naphthols from Nitrones and MBH Adducts via Decarboxylative N–O Bond Cleavage

The efficient synthesis of 2-naphthols is important for their further development as bioactive compounds and chiral ligands as well as other synthetic purposes. Herein, we describe the unprecedented one-pot synthesis of 2-naphthols through an acid-mediated decarboxylative N–O bond cleavage of bridged benzoxazepine intermediates, which were in turn generated from aryl nitrones and Morita–Baylis–Hillman (MBH) adducts under cationic rhodium(III) catalysis. A range of 2-naphthol derivatives including anthracen-2-ol, phenanthren-2-ol, and 11H-benzo[b]fluoren-7-ol were formed with excellent site selectivities and functional group compatibilities. To gain mechanistic insight into this process, a series of mechanistic investigations and DFT calculations were also performed.

Central region of SKKUCY-9 compact cyclotron

The development of a 9 MeV compact cyclotron for the production of radioisotopes for medical applications has been recently completed. The machine accelerates negative hydrogen ions generated from an internal PIG (Penning Ion Gauge) ion source following spiral orbits. Some of the structures designed for early beam acceleration, including a pair of center poles providing ions a circular direction, the head of the ion source, and the electrodes, are located in the center of the cyclotron. In this paper we discuss and evaluate the design of the central region that pulls the ions from the chimney of the ion source and directs them into the equilibrium orbit. The magnetic field produced by the center poles was analyzed using the magnetic solver in OPERA-3D TOSCA, and the phase error and ion equilibrium orbit, which is dependent on the kinetic energy within the designed field, were calculated using CYCLONE v8.4. The electric field produced in the acceleration gap was designed using an electrostatic solver. Then, the single beam trajectory was calculated by our own Cyclotron Beam Dynamics (CBD) code. The early orbits, vertical oscillation, acceptable RF phase and the energy gain during the early turns was evaluated. Final goal was to design the central region by the iterative optimization process and verify it with 1 MeV beam experiment.