Yong Ho Lee

A completely atom economical palladium-catalyzed addition reaction has been developed to stereoselectively access functionalized tetrasubstituted alkenyl iodides. The palladium catalyst, which bears an electron-poor bidentate ligand rarely employed in catalysis, is essential to promote the high yielding and chemoselective intermolecular reaction between equimolar amounts of an alkyne and an aryl iodide. This new carbohalogenation reaction is an attractive alternative to traditional synthetic met

Recently, various chemical modifications of peptides have been incorporated into mass spectrometric analyses of proteome samples, predominantly in conjunction with matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS), to facilitate de novo sequencing of peptides. In this work, we investigate systematically the utility of N-terminal sulfonation of tryptic peptides by 4-sulfophenyl isothiocyanate (SPITC) for proteome analysis by capillary reverse-phase liquid chromatography/tan

Recently various methods for the N-terminal sulfonation of peptides have been developed for the mass spectrometric analyses of proteomic samples to facilitate de novo sequencing of the peptides produced. This paper describes the isotope-coded N-terminal sulfonation (ICenS) of peptides; this procedure allows both de novo peptide sequencing and quantitative proteomics to be studied simultaneously. As N-terminal sulfonation reagents, 13C-labeled 4-sulfophenyl[13C6]isothiocyanate (13C-SPITC) and unl

Abstract This paper deals with the results of experimental investigations on the effects of tube vibration on critical heat flux (CHF) in order to gain an understanding of the relationship between CHF and flow-induced vibration (FIV). The experiment was carried out in the following range of parameters: diameter (D)=0.008 m; heated length (L)=0.2, 0.4 m; pressure (P)=101 kPa; mass flux (G)=403–2,551 kg/m2.s; quality (x)=-0.045–0.289; amplitude (a)=0.0001–0.001 m; frequency (f)=0–70Hz. The CHF gen

Abstract Eine vollständig atomökonomische, Palladium‐katalysierte Additionsreaktion wurde entwickelt, um einen stereoselektiven Zugang zu funktionalisierten, vierfach substituierten Alkenyliodiden zu erhalten. Der Palladiumkatalysator weist einen elektronenarmen, zweizähnigen Liganden auf, der zwar selten in der Katalyse verwendet wird, aber essentiell ist, um diese chemoselektive, intermolekulare Reaktion eines Alkins mit einem Aryliodid in äquimolaren Mengen mit hoher Ausbeute ablaufen zu lass

We describe a general strategy for the intermolecular synthesis of polysubstituted cyclopentenones using palladium catalysis. Overall, this reaction is achieved via a molecular shuffling process involving an alkyne, an α,β-unsaturated acid chloride, which serves as both the alkene and carbon monoxide source, and a hydrosilane to create three new C-C bonds. This new carbon monoxide-free pathway delivers the products with excellent yields. Furthermore, the regioselectivity is complementary to conv

We report that a Lewis acidic silane, Me2SiHCl, can mediate the direct cross-coupling of a wide range of carbonyl compounds with alcohols to form dialkyl ethers. The reaction is operationally simple, tolerates a range of polar functional groups, can be utilized to make sterically hindered ethers, and is extendable to sulfur and nitrogen nucleo­philes.

A new approach for the preparation of amides was developed using C-C bond cleavage that initiates C- to N-acyl transfer, employing activated ketones as acylation reagents and amine nucleophiles. The reaction was operational under the coupling reagent system that is commonly utilized for peptide bond formations. The method enables practical preparation of amides using linear and cyclic ketone substrates under mild conditions.