Kwang-Youn Ko

100% internal quantum efficiency and stable efficiency roll-off in phosphorescent light-emitting diodes using a high triplet energy hole transport material

Highly efficient green phosphorescent organic light-emitting diodes were developed by using high triplet energy hole transport materials. The quantum efficiency of green devices could be improved from 12% to 20% at 1000cd∕m2 by using a phenylcarbazole based hole transport material. In addition, the high quantum efficiency could be stably maintained up to a high luminance of 10000cd∕m2.

Aromatization of Hantzsch 1,4-dihydropyridines with Magtrieve™

Abstract Hantzsch 1,4-dihydropyridines (1,4-DHPs) can be aromatized to pyridines by refluxing in chloroform with Magtrieve™ in high yields.

Synthesis of 5-oxo-l-pipecolic acid derivatives by rhodium(II) acetate catalyzed cyclization of diazoketones

Abstract A convenient synthesis of 5-oxo- l -pipecolic acid derivatives is described. The key step involves the rhodium(II) acetate catalysed N-H insertion reaction of diazoketones, which are derived from l -glutamic acid.

Magtrieve™: a new agent for the deprotection/oxidation of acetals and ketals under neutral conditions

MagtrieveTM can be used for the deprotection of acetals and ketals or for the direct oxidation to carboxylic acids under neutral conditions.

Diastereoselective reduction of chiral N-tosyl 2-Benzoyl-1,3-oxazines derived from D-glucose

Abstract Stereochemistry of reduction of the diastereomerically pure N -tosyl 2-benzoyl-1,3-oxazines prepared from D-glucose was investigated with various reducing agents. It was found that the stereochemical outcome is consistent with the Crams chelation model where the ring oxygen atom is involved in chelation, not the tosyl oxygen as in the 5-membered oxazolidines.

Copper-catalyzed carbon–carbon bond cleavage of primary propargyl alcohols: β-carbon elimination of hemiaminal intermediates

The copper-catalyzed cleavage of carbon–carbon bonds in primary propargyl alcohols under oxygen was investigated. This process involves the formation and fragmentation of hemiaminals from aldehydes (oxidized alcohols) and amines. This reaction mechanism was supported by the formation of N-formyl amines and GC experimental results.