Kooyeon Lee

Studies on the reactions of α,β-enones with allyl indium reagent; effects of TMSCl as promoter on regioselectivity

Regioselectivity on the reactions of α,β-enones with allyl indium reagents in the presence of TMSCl was systematically studied. 2-Cyclohexen-1-one, (R)-carvone, 2-cyclohepten-1-one and chalcone produced 1,4-addition products in good yields, whereas 2-cyclopenten-1-one, 2-methylcyclopenten-1-one, 4,4-dimethylcyclohexen-1-one and acyclic α,β-enones afforded 1,2-addition products.

ULTRASOUND PROMOTED SYNTHESIS OF β-HYDROXYESTERS BY REFORMATSKY REACTION USING INDIUM METAL

Ultrasound promoted Reformatsky reaction by the reaction of aldehydes or ketone with ethyl bromoacetate in the presence of indium metal afforded β-hydroxyesters in good to excellent yields under mild conditions.

Efficient Synthetic Method of Multisubstituted Allenes from the Reactions of Allylindium Reagents with 3°-Propargyl Alcohols

An efficient synthetic method of tri- and tetra-substituted allenes having an allyl and methallyl group was developed by the reactions of allylindium reagents generated in situ from indium and allyl bromides with 3 degree-propargyl alcohols.

In-mediated synthesis of 2-(2-hydroxyethyl)homoallenylsilanes

Abstract Indium-mediated homoallenylation of aldehydes with 4-bromo-3-[(trimethylsilyl)methyl]-1,2-butadiene in DMF afforded 2-(2-hydroxyethyl)homoallenylsilanes at room temperature in good yields.

Palladium‐Catalyzed Allyl Cross‐Coupling Reactions with In Situ Generated Organoindium Reagents

Inter- and intramolecular palladium-catalyzed allyl cross-coupling reactions, using allylindium generated in situ from allyl halides and indium, is demonstrated. Allylindium compounds may be effective nucleophilic coupling partners in palladium-catalyzed cross-coupling reactions. A variety of allyl halides, such as allyl iodide, allyl bromide, crotyl bromide, prenyl bromide, geranyl bromide, and 3-bromocyclohexene afforded the allylic cross-coupling products in good to excellent yields. Stereochemistry of the double bond is retained in the allylic cross-coupling reactions. Electrophilic cross-coupling partners, such as aryl and vinyl halides, dibromoolefin, alkynyl iodide, and aryl and vinyl triflates participate in these reactions. The presence of various substituents, such as n-butyl, ketal, acetyl, ethoxycarbonyl, nitrile, N-phenylamido, nitro, and chloride groups on the aromatic ring of electrophilic coupling partners showed little effect on the efficiency of the reactions. The present conditions work equally well for not only intermolecular but also intramolecular palladium-catalyzed cross-coupling reactions. These methods provide an efficient synthetic method for the introduction of an allyl group, which can be easily further functionalized to afford an sp(2)- and sp-hybridized carbon. The present method complements existing synthetic methods as a result of advantageous features such as easy preparation and handling, thermal stability, high reactivity and selectivity, operational simplicity, and low toxicity of allylindium reagents.

Inhibitory effects of Capsicum annuum L. water extracts on lipoprotein lipase activity in 3T3-L1 cells

Obesity, an intractable metabolic disease, currently has no medical treatment without side effects, so studies have been actively carried out to find natural compounds that have anti-obesity activity with minimum side effects. In this study, the anti-obesity effects of water extracts of seven Capsicum annuum L. varieties being Putgochu (Pca), Oyee gochu (Oca), Kwari putgochu (Kca), Green pepper (Gca), Yellow paprika (Yca), Red paprika (Rca) and Cheongyang gochu (Cca), were examined through the evaluation of lipoprotein lipase (LPL) mRNA expression level in 3T3-L1 cells (mouse pre-adipocytes). After capsaicin elimination by chloroform defatting, freeze-dried powder of Cca was treated to 3T3-L1 cells and anti-obesity effects were examined by determining the LPL mRNA level using the RT-PCR method. Of the primary fractions, only proven fractions underwent secondary and tertiary refractionating to determine anti-obesity effects. From seven different Capsicum annuum L., there was a significant decrease of the LPL mRNA expression level of 50.9% in Cca treatment compared to the control group. A significant decrease of the LPL mRNA expression level was shown in primary fractions (Fr) 5 (36.2% decrease) and 6 (30.5% decrease) of the Cca water extracts. Due to the impurities checked by UPLC chromatography, Fr 5 and 6 were refractionated to determine the LPL mRNA expression level. Treatment of Fr 6-6 (35.8% decrease) and Fr 5-6 (35.3% decrease) showed a significant decrease in the LPL mRNA expression level. When analyzed using UPLC, major compounds of Fr 6-6 and Fr 5-6 were very similar. Subsequently, we refractionated Fr 6-6 and Fr 5-6 to isolate the major peak for structure elucidation. Treatment of Fr 5-6-1 (26.6% decrease) and Fr 6-6-1 (29.7% decrease) showed a significant decrease in the LPL mRNA expression level. Consequently, the fractions may have a possibility to ameliorate obesity through the decrease of the LPL mRNA expression level.

In-MEDIATED ALLYLATION OF α-KETO ESTERS WITH ALLYL HALIDES*

The chemoselective reaction of α-keto esters with allyl halides, propargyl bromides, and allenyl bromide using indium metal afforded α-hydroxy-γ,δ-unsaturated esters in good to excellent yields under mild conditions. *This paper is dedicated to Professor Chang Hwan Rhee on the occasion of his 60th birthday.

Brønsted Acid–Catalyzed Meyer–Schuster Rearrangement for the Synthesis of α,β-Unsaturated Carbonyl Compounds

Abstract An efficient and simple protocol for the Meyer–Schuster rearrangement of propargyl alcohols into α,β-unsaturated carbonyl compounds has been developed using catalytic amounts of p-toluenesulfonic acid in 1,2-dichloroethane. GRAPHICAL ABSTRACT

PREPARATION OF UNSYMMETRICAL DIALKENYL KETONES FROM THE REACTIONS OF ALKENYL ALKYNYL KETONES WITH GILMAN REAGENTS

Unsymmetrical dialkenyl ketones were prepared from the reactions of alkenyl alkynyl ketones with 0.55 equiv of lithium dialkylcuprates.

PKA regulates calcineurin function through the phosphorylation of RCAN1: Identification of a novel phosphorylation site

Calcineurin is a calcium/calmodulin-dependent phosphatase that has been implicated in T cell activation through the induction of nuclear factors of activated T cells (NFAT). We have previously suggested that endogenous regulator of calcineurin (RCAN1, also known as DSCR1) is targeted by protein kinase A (PKA) for the control of calcineurin activity. In the present study, we characterized the PKA-mediated phosphorylation site in RCAN1 by mass spectrometric analysis and revealed that PKA directly phosphorylated RCAN1 at the Ser 93. PKA-induced phosphorylation and the increase in the half-life of the RCAN1 protein were prevented by the substitution of Ser 93 with Ala (S93A). Furthermore, the PKA-mediated phosphorylation of RCAN1 at Ser 93 potentiated the inhibition of calcineurin-dependent pro-inflammatory cytokine gene expression by RCAN1. Our results suggest the presence of a novel phosphorylation site in RCAN1 and that its phosphorylation influences calcineurin-dependent inflammatory target gene expression.