Sunwoo Lee

Catalysts comprised Pd(OAc)(2) and either PCy(3) or sterically hindered N-heterocyclic carbene ligands provide fast rates for a palladium-catalyzed synthesis of oxindoles by amide alpha-arylation. This catalyst system allowed for room-temperature reactions in some cases and reactions of aryl chlorides at 70 degrees C. Most important, reactions occurred in high yields under mild conditions to form the quaternary carbon in alpha,alpha-disubstituted oxindoles. The combined inter- and intramolecular

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTPalladium-Catalyzed α-Arylation of Esters and Protected Amino AcidsSunwoo Lee, Neil A. Beare, and John F. HartwigView Author Information Department of Chemistry Yale University, P.O. Box 208107 New Haven, Connecticut 06520-8107 Cite this: J. Am. Chem. Soc. 2001, 123, 34, 8410–8411Publication Date (Web):August 3, 2001Publication History Received17 April 2001Revised1 July 2001Published online3 August 2001Published inissue 1 August 2001https://pubs.

[reaction: see text]. A simple, palladium-catalyzed method to convert aryl halides to the parent anilines using lithium bis(trimethylsilyl)amide (LiN(SiMe3)2) is reported. The reaction is catalyzed by Pd(dba)2 and P(t-Bu)3 and can be run with as little as 0.2 mol % of catalyst. The reaction is faster than competing generation of benzyne intermediates and, therefore, provides the aniline products regiospecifically.

The decarboxylative coupling of alkynyl carboxylic acids is an attractive area of research in organic chemistry, because the structure of aryl alkyne is one of the important building blocks for the synthesis of p-conjugated compounds. The use of alkynyl carboxylic acid as an alkyne source has several advantages in handling and storage. As a catalyst, palladium, copper, nickel, and silver were employed in the decarboxylative coupling reactions. The formation of C–C (sp2–sp, sp–sp and sp3–sp), C–N

Arylsulfonyl compounds are among the most important compounds in pharmaceutical and medicinal chemistry. Hence, a wide variety of sulfonylation methods have been reported recently. This review summarizes arylsulfonylation methodologies developed in the last 5 years and includes two major categories. The first entails direct arylsulfonylation and the second multicomponent arylsulfonylation. In direct arylsulfonylation, arylsulfonyl reagents react with C–H activated compounds, alkynes, and alkenes

We have fabricated boron carbide thin films on Si(111) and other substrates by plasma-enhanced chemical-vapor deposition (PECVD). The PECVD of boron carbides from nido-cage boranes, specially nido-pentaborane(9) (B5H9), and methane (CH4) is demonstrated. The band gap is closely correlated with the boron to carbon ratio and can range from 0.77 to 1.80 eV and is consistent with the thermal activation barrier of 1.25 eV for conductivity. We have made boron carbide by PECVD from pentaborane and meth

Recording neural activity in live animals in vivo with minimal tissue damage is one of the major barriers to understanding the nervous system. This paper presents the technology for a tetherless opto-electronic neural interface based on 180 nm CMOS circuits, heterogeneously integrated with an AlGaAs diode that functions as both a photovoltaic and light emitting diode. These microscale opto-electrically transduced electrodes (MOTEs) are powered by and communicate through an optical interface, sim

Graphene mechanical resonators are the ultimate two-dimensional nanoelectromechanical systems (NEMS) with applications in sensing and signal processing. While initial devices have shown promising results, an ideal graphene NEMS resonator should be strain engineered, clamped at the edge without trapping gas underneath, and electrically integratable. In this Letter, we demonstrate fabrication and direct electrical measurement of circular SU-8 polymer-clamped chemical vapor deposition graphene drum

Abstract A variety of aryl bromides were coupled with propiolic acid in the presence of 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) and catalyst Pd(PPh 3 ) 4 to afford the corresponding arylalkynecarboxylic acids in good yields at low temperature. This method showed good tolerance toward functional groups such as alkoxy, ketone, ester, aldehyde, cyano, nitro, and hydroxy. Under these conditions, propiolic acid showed higher reactivity than any other compound containing terminal alkyne groups. Accor

Abstract Copper‐catalyzed coupling reaction of 2‐iodobenzoic acids and alkynes such as terminal acetylenes, alkynyl carboxylic acids, and trimethylsilylacetylene selectively afforded isocoumarins and phthalides in the presence of cesium carbonate (Cs 2 CO 3 ) and dimethyl sulfoxide (DMSO). Among the regioselective products, only the 6 ‐endo‐dig product, isocoumarin, was formed at 100 °C, and the 5‐ exo‐dig product, phthalide, was formed as a major product at 25 °C. A variety of alkynes produced

Various primary amides have been synthesized using the transamidation of various tertiary amides under metal-free and mild reaction conditions. When (NH₄)₂CO₃ reacts with a tertiary amide bearing an <i>N</i>-electron-withdrawing substituent, such as sulfonyl and diacyl, in DMSO at 25 °C, the desired primary amide product is formed in good yield with good funcctional group tolerance. In addition, <i>N</i>-tosylated lactam derivatives afforded their corresponding <

In this study, we demonstrated a noble Ag-decorated graphene oxide catalyst (GOSH-Ag) for use in the decarboxylative cycloaddition reaction. The catalyst was easily prepared by depositing Ag nanoparticles on thiolated graphene oxide (GOSH) surfaces. Transmission electron microscopy (TEM) indicated that the nanoparticles were well-dispersed and of a small, approximately 3.7 nm average size. These characteristics resulted in a high surface area, which enhanced the catalytic activity of the support

In Federated Learning (FL), a common approach for aggregating local solutions across clients is periodic full model averaging. It is, however, known that different layers of neural networks can have a different degree of model discrepancy across the clients. The conventional full aggregation scheme does not consider such a difference and synchronizes the whole model parameters at once, resulting in inefficient network bandwidth consumption. Aggregating the parameters that are similar across the