Youseung Kim

A facile synthesis of N-carbamoylmethyl- α -aminobutyrolactones by the Ugi multicomponent condensation reaction

Abstract A new method of various N-carbamoylmethyl-α-amino-butyrolactones4 utilizing the intramolecular Ugi five-center-three-component condensation reaction starting from l -homoserine was developed.

Formation of amorphous phase in the binary Cu−Zr alloy system

The aim of this work is to elucidate the formation of the amorphous phase in the Cu−Zr binary alloy system. It was found that 1 mm diameter rods with a fully amorphous structure can be prepared in a relatively wide range of compositions. In contrast, the formation of 2 mm diameter rods was achieved only for the Cu64Zr36 alloy and in the range of Cu53Zr47−Cu50Zr50, which are compositions near the energetically stable Cu2Zr and CuZr intermetallic compounds. The difference between the calculated Gibbs free energy of the amorphous phase and the intermetallic compounds gives insight into the range of glass formation. In addition, the formation of the energetically stable phases can be kinetically by-passed owing to the crystallization of several competing phases.

Indium mediated pinacol coupling reaction of aromatic aldehydes in aqueous media

Abstract The carbon-carbon bond formation reaction of aromatic carbonyl compounds was performed with indium in neutral aqueous media using sonication affording the corresponding diols in moderate to good yields.

Indium mediated allylation and propargylation reactions of dimethyl acetals and ketals

Abstract Indium mediated allylation and propargylation reactions of acetals and ketals with various allyl or propargyl bromides in aqueous media successfully provided the corresponding homoallylic or homopropargylic (and allenylic) alcohol, respectively, in moderate to good yields. Highly chemoselective allylation is also described. The ketal and aryl acetal could be selectively allylated over the aliphatic one in 80–84% yields.

A FACILE SYNTHESIS OF (S)-(-)-7,8-DIFLUORO-3,4-DIHYDRO-3-METHYL-2H-1,4-BENZOXAZINE BY ZINC CHLORIDE ASSISTED MITSUNOBU CYCLIZATION REACTION

A convenient procedure for preparation of the title compound of ≥99% ee starting from 1-(2,3-difluoro-6-nitrophenoxy)-2-propanone (3) is presented. The key reaction is the intramolecular cyclization reaction in the presence of zinc chloride.

An efficient synthesis of 2,5-diketopiperazine derivatives by the Ugi four-center three-component reaction

A facile synthetic approach to 2,5-diketopiperazines 4 by the Ugi four-center three-component reaction using commercially available dipeptides as a bifunctional component, aldehydes, and isocyanides was described.

Indium-mediated monoallylation of carbonyl compounds with allylic chlorides and bisallylation of 2-pyridyl carboxylates with allylic halides in aqueous media

Abstract Allylic chlorides are efficient reagents in the indium-mediated Barbier-type allylation reaction with various aldehydes and ketones in pure water under sonication or in a 1:1 mixture of H 2 O and t-BuOH. Also indium is effective in bisallylation reactions of the 2-pyridyl esters with allyl halides in pure water.

Intermolecular Double Prins‐Type Cyclization: A Facile and Efficient Synthesis of 1,6‐Dioxecanes

Double or nothing: The title reaction converts a range of aromatic aldehydes and allenylmethyl/allyl silanes into 1,6-dioxecane derivatives in good to excellent yields (see scheme; Ar = aryl, Tf = triflate, THF = tetrahydrofuran, TMS = trimethylsilyl). In addition, the bisdiene product has been transformed into the corresponding tricyclic compound through a Diels-Alder reaction.

A new direct allylation of the aromatic compounds with allylic chlorides catalyzed by indium metal

Abstract A new method of the direct allylation reaction for the aromatic compounds with allylic chlorides using a catalytic amount of indium in the presence of CaCO 3 4 A molecular sieves was developed.

A facile synthesis of 7-amino-3-desacetoxycephalosporanic acid derivatives by indium-mediated reduction of 3-iodomethylcephems in aqueous media

Abstract An efficient reductive conversion of 3-iodomethylcephalosporin and 3-acetoxymethylcephalosporin derivatives mediated by indium into the corresponding 3-methylcephems and 3-methylenecephams in moderate to good yields has been developed in an aqueous system. 3-Methylenecephams are converted into the corresponding 3-methylcephems under previously reported basic conditions quantitatively.