Korea University · Chemistry
Professor Cheol-Hong Cheon's research lab specializes in the development of innovative, sustainable, and catalytic methodologies for the synthesis of nitrogen-containing heterocycles—particularly benzoxazoles, quinolines, indolines, and tetrahydroquinolines. The lab focuses on transition-metal-free, metal-free, and organocatalytic strategies, with an emphasis on cyanide and nucleophilic catalysts (e.g., benzylamine, iodide, chiral phosphoric acids) to enable atom-economical, step-economical, and environmentally benign transformations. Key advances include umpolung strategies, on-water synthesis, and asymmetric catalysis, often applied to the total synthesis of complex natural products and biologically relevant compounds.
Figures are computed from collected data and may differ slightly.
Abstract A cyanide‐catalyzed synthesis of 2‐substituted benzoxazoles from Schiff bases via aerobic oxidation has been developed. The products from various Schiff bases were obtained in high yields in an open flask under ambient conditions without other external oxidants. We have also developed a simple one‐step protocol for the synthesis of benzoxazoles from aminophenol and the corresponding aldehydes in the presence of cyanide without isolation of imine intermediates.
Abstract A general method to generate umpolung of aldimines with cyanide was developed via the addition of cyanide to aldimines followed by a proton transfer from the carbon atom to the nitrogen atom in the resulting cyanide adducts. This novel method was successfully applied to the first imino‐Stetter reaction of aldimines obtained from 2‐aminocinnamic acid derivatives and aromatic aldehydes with cyanide, affording 2‐aryl‐substituted indole‐3‐acetic acid derivatives. Furthermore, the usefulness
On-water synthesis of 2-substituted quinolines from 2-aminochalcone derivatives was developed using benzylamine as the nucleophilic catalyst. Various 2-aminochalcones could be applied to this protocol, and the desired 2-substituted quinoline products were isolated in excellent yields by simple filtration. Furthermore, we elucidated the role of benzylamine in this transformation and provided the detailed reaction mechanism. This protocol has several additional advantages, such as simple operation
The total synthesis of (±)-hinckdentine A is described herein. A cyanide-catalyzed imino-Stetter reaction of the aldimine derived from ethyl 2-amino-3,5-dibromocinnamate and 5-bromo-2-nitrobenzaldehyde followed by oxidative rearrangement afforded a 2,2-disubstituted 3-indolinone derivative containing the carbon skeleton and all of the functional groups present in the natural product correctly positioned, including three bromine atoms. Subsequent D-ring formation and seven-membered C-ring constru
A new asymmetric protocol for the synthesis of chiral tetrahydroquinolines from 2-aminochalcones via a two-step one-pot consecutive process (cyclization/asymmetric reduction) has been developed using chiral phosphoric acid as the sole catalyst. 2-Aminochalcones were converted into the corresponding quinolines through chiral phosphoric acid-catalyzed dehydrative cyclization, and the resultant quinolines were subsequently reduced to the chiral tetrahydroquinolines via chiral phosphoric acid-cataly
A new protocol for the synthesis of 2-substituted quinolines from 2-aminostyryl ketones has been developed using iodide as a nucleophilic catalyst. Conjugate addition of iodide to 2-aminostyryl ketones yielded the corresponding β-iodoketones, which could have a conformation where the amino and carbonyl groups are proximal through free rotation about the C<sub>α</sub>-C<sub>β</sub> single bond. Subsequent condensation between the amino and carbonyl groups followed by elimination of hydrogen iodid
The total synthesis of iheyamine A from readily available ethyl 2-aminocinnamate and 5-methoxyindole-2-carboxaldehyde is described. The cyanide-catalyzed imino-Stetter reaction of an aldimine derived from ethyl 2-aminocinnamate and 5-methoxyindole-2-carboxaldehyde provided the desired unsymmetrical 2,2'-bisindole-3-acetic acid derivative. The subsequent introduction of an amino group at the C-3' position, followed by the formation of the azepine ring, completed the total synthesis of iheyamine A
Abstract A new protocol for the synthesis of chiral β‐aminotetralins has been developed via chiral phosphoric acid‐catalyzed asymmetric reductive amination of β‐tetralones using a Hantzsch ester as an organic hydride donor. Various chiral β‐aminotetralins were obtained in good yields with good to high enantioselectivities. Furthermore, the utility of our new protocol was successfully demonstrated in the enantioselective synthesis of rotigotine. magnified image
A highly concise strategy for the total synthesis of phenanthroindolizidines was developed. The one-pot iterative Suzuki-Miyaura reaction of aryl boronic acids with ortho-bromoaryl N-methyliminodiacetate (MIDA) boronate followed by a second Suzuki-Miyaura reaction with a suitable pyridyl bromide provided ortho-aza-terphenyls. Subsequent saturation of the triple bond, treatment with mesyl chloride, and reduction of the resulting dihydroindolizidinium ring afforded the hexahydroindolizines. A fina
A concise total synthesis of rucaparib, an FDA-approved drug for ovarian and prostate cancers, is reported. The Heck reaction of the commercially available aryl iodide with acrylonitrile provided the desired (<i>E</i>)-2-aminocinnamonitrile derivative. A subsequent imino-Stetter reaction of the aldimine derived from 2-aminocinnamonitrile and aldehyde furnished indole-3-acetonitrile bearing the desired substituents at appropriate positions. The construction of the final azepinone scaffold via red
We describe the asymmetric total syntheses of naphthylisoquinoline alkaloids. Atroposelective biaryl coupling reaction between naphthyl pinacol boronate and an aryl iodide, bearing (<i>S</i>)-2-aminopropyl group at the <i>ortho</i>-position using the existing central chirality as an atroposelectivity-controlling group, provided the desired biaryl product with high atroposelectivity, without the use of an external chiral source. From the resulting biaryl product, several naphthylisoquinoline alka
The chemistry of hydrogen cyanide adducts of imines is well-developed, but that of cyanide adducts remains unexplored. This is presumably because these cyanide adducts are not stable and thus not readily available in their isolated forms. In this personal account, we present the progress made in our research program towards the development of novel organic transformations utilizing cyanide adducts of imines as key intermediates. We also report the application of these methodologies to the total
Highly concise total syntheses of paullone and kenpaullone were developed. Cyanide-catalyzed intramolecular imino-Stetter reaction of aldimines derived from methyl 2-aminocinnamate derivatives and 2-nitrobenzaldehyde provided 2-(2′-nitrophenyl)indole-3-acetic acid derivatives. Subsequent reduction of the nitro group with zinc under acidic conditions to an amino group followed by spontaneous lactam formation allowed for the total syntheses of paullone and kenpaullone to be completed in two steps
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