Kyung Woon Jung

Oxidative dimerization: Pd(II) catalysis in the presence of oxygen using aqueous media

Reported herein is a method for the formation of symmetric biaryls and dienes via oxidative dimerization of aryl and alkenyl boronic acids. These conditions utilized Pd(II) catalysts under an oxygen atmosphere with water as the solvent. The use of phase transfer catalysts promoted efficient and mild syntheses of a wide range of materials.

Mild and efficient synthesis of thiocarbonates and thiocarbamates via a three-component coupling utilizing Cs2CO3 and TBAI

Abstract The presence of cesium carbonate and tetrabutylammonium iodide (TBAI) facilitated efficient thiocarbonylation of alcohols, and thiocarbamation of amines, using carbon disulfide with alkyl halides. This protocol was mild, chemoselective, and efficient, compared to the existing methods.

Efficient Cs2CO3-promoted solution and solid phase synthesis of carbonates and carbamates in the presence of TBAI

Abstract Novel solution and solid-phase methods for the synthesis of carbonates and carbamates were developed using cesium bases and TBAI via a three-component coupling. Cesium carbonate not only promoted successful carbonylations of alcohols and carbamations of amines, but also suppressed common side reactions traditionally seen using existing protocols. Various alcohols and amines were examined, using a wide array of alkyl halides, and the results demonstrated this methodology was highly chemoselective. In particular, use of either sterically demanding substrates or amino acid derivatives afforded the corresponding products exclusively, offering a wide variety of applications such as novel protecting groups and peptidomimetic syntheses.

Cesium promoted O-alkylation of alcohols for the efficient ether synthesis

Abstract Efficient Williamson type O -alkylation of alcohols was developed using cesium bases in the presence of tetrabutylammonium iodide (TBAI) and molecular sieves. Various substrates including unreactive primary and secondary alcohols were converted smoothly to the corresponding ethers. Electrophiles used herein encompass primary bromides and reactive halides such as benzyl bromide and MPMCl.

An efficient one-pot synthesis of N-alkyl carbamates from primary amines using Cs2CO3

Abstract A facile one-pot synthesis of N-alkyl carbamates is described. A primary amine, CO2, and an alkyl halide underwent a three-component coupling using cesium carbonate and tetrabutylammonium iodide (TBAI) giving rise to the resultant carbamate. In the presence of Cs2CO3, subsequent N-alkylation of the in situ generated carbamate with a different alkyl halide afforded various aliphatic N-alkyl carbamates, respectively.

CS2CO3 PROMOTED O-ALKYLATION OF ALCOHOLS FOR THE PREPARATION OF MIXED ALKYL CARBONATES

Abstract The presence of cesium carbonate and tetrabutylammonium iodide (TBAI) facilitated efficient O -alkylation of alcohols with alkyl halides, giving rise to the exclusive formation of mixed alkyl carbonates. The cesium effect was also examined comparatively with other alkali carbonates.

Efficient synthesis of β-amino bromides

Abstract β-Aminoalcohols were smoothly converted to β-amino bromides using thionyl bromide and DMF, which were easily isolated without any further purification. Participation by the β-amino group in brominations not only enhanced reaction rates but also promoted stereo- and regioselectivities.

Mild and efficient formation of symmetric biaryls via Pd(II) catalysts and Cu(II) oxidants

Described herein is a mild and efficient palladium-catalyzed synthesis of symmetric biaryls from organostannanes. This methodology offers products rapidly in very high yields.

CsOH-promoted chemoselective mono-N-alkylation of diamines and polyamines

Abstract Selective N -alkylation of diamines and polyamines was carried out using cesium hydroxide, 4 A molecular sieves, and DMF. This protocol was highly chemoselective, favoring mono- N -alkylation over overalkylations.

Efficient and selective N-alkylation of carbamates in the presence of Cs2CO3 and TBAI

Abstract Mild and selective N -alkylation of carbamates was carried out in the presence of cesium carbonate, tetrabutylammonium iodide (TBAI), and a halide. This protocol was highly selective and efficient, offering aliphatic and aromatic N -alkyl carbamates exclusively in high yields.