Seung Hoon Shin

Metal carbenes are highly versatile species that mediate various transformations. Recent advances in gold catalysis have allowed catalytic access to α-oxo metal carbenes from the alkyne functionality. Compared with traditional methods that rely upon metal-catalyzed decomposition of diazo precursors, the generation of this synthon occurs in an environmentally more appealing fashion by gold-catalyzed alkyne oxygenation. Hydroxylamine derivatives are typically prepared from hydroxylamine salts that

High-octane synthesis: Azomethine ylides can be generated from an internal redox reaction of a nitrone-tethered alkyne under electrophilic metal catalysis (see scheme; M=metal). This novel and atom-economical generation of an azomethine ylide does not involve potentially explosive diazo derivatives. The azomethine ylide can participate in a dipolar cycloaddition cascade to provide an azabicyclo[3.2.1]octane. Supporting information for this article is available on the WWW under http://www.wiley-v

Sicher und atomökonomisch: Die intramolekulare Redoxreaktion eines Alkin-Nitrons, katalysiert durch ein elektrophiles Metall, liefert Azomethin-Ylide (siehe Schema; M: Metall). Diese atomökonomische Synthese von Azomethin-Yliden kommt ohne explosionsgefährliche Diazoderivate aus. Die Azomethin-Ylide können über eine dipolare Cycloadditionskaskade in Azabicyclo[3.2.1]octane überführt werden. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_

We report geometry-dependent cyclizations of o-alkynylaryl ketoximes and nitrones catalyzed by gold complexes. (E)-Ketoximes undergo N-attack to give isoquinoline-N-oxides. In sharp contrast, (Z)-ketoximes undergo unprecedented O-nucleophilic attack, followed by a redox cascade leading to a novel catalytic entry to isoindoles of diverse scope. The structure of an isoindole was unambiguously supported by X-ray crystallography. We demonstrated the generality of the isoindole synthesis from either

Under dual gold/photoredox catalytic conditions, intermediates from the Meyer-Schuster rearrangement underwent an efficient cross-coupling with arene diazonium salts, leading to α-arylated enones. Diazonium salts assisted the dissociation of the propargyl hydroxyl group by forming alkoxydiazenes in the Meyer-Schuster rearrangement, and the coupling was proposed to proceed through an allenyl methyl ether.

Golden touch: Gold-catalyzed reaction of N-sulfonyl hydroxylamines with terminal alkyne led to 3-pyrrolidinones by means of an oygen-transfer redox reaction. This protocol constitutes a direct method for forming α-amino carbonyl compounds. In sharp contrast, those with internal alkynes underwent 1,3-sulfonyl migration leading to 3-sulfonyl cyclic nitrones. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-

Abstract Catalytically generated vinyl gold complexes from tert‐ butyl allenoates were found to undergo an efficient cross‐coupling with arenediazonium salts. The gold(I)‐gold(III) redox cycle can be accessed under two different conditions, i.e., visible‐light photoredox as well as a thermally induced radical chain pathway. The current C( sp 2 )C( sp 2 ) cross‐coupling protocol that is catalytic in gold, would make available desirable structural diversity to the traditional cross‐coupling chemi

Abstract A non‐metal approach for accessing α‐oxo carbene surrogates for a C−C bond‐forming bimolecular coupling between ynamides and nucleophilic arenes was developed. This acid‐catalyzed coupling features mild temperature, which is critical for the required temporal chemoselectivity among nucleophiles. The scope of nucleophiles includes indoles, pyrroles, anilines, phenols and silyl enolethers. Furthermore, a direct test of S N 2′ mechanism has been provided by employing chiral N,N′‐dioxides w

o-(1,6-Enynyl)benzaldehydes underwent a novel mode of cycloaddition using Rh(I)-precatalyst, via[3+2] cycloaddition of presumed dipolar carbonyl ylide intermediate generated by Rh-catalyst and the utility of this mechanistically intriguing enyne cyclization can be found in a number of polycyclic natural product skeletons.

A gold-catalyzed intermolecular reaction of propiolic acids with alkenes led to a [4 + 2] annulation or enyne cross metathesis. The [4 + 2] annulation proceeds with net cis-addition with respect to alkenes and provides an expedient route to α,β-unsaturated δ-lactones, for which preliminary asymmetric reactions were also demonstrated. For 1,2-disubstituted alkenes, unprecedented enyne cross metathesis occurred to give 1,3-dienes in a completely stereospecific fashion. DFT calculations and experim

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTRegio- and Stereochemical Control in Bis-functionalization−Cyclization: Use of Alleneyne Precursors for Carbocyclic and Heterocyclic SynthesisSeunghoon Shin and T. V. RajanBabuView Author Information Department of Chemistry The Ohio State University Columbus, Ohio 43210 Cite this: J. Am. Chem. Soc. 2001, 123, 34, 8416–8417Publication Date (Web):August 2, 2001Publication History Received25 May 2001Published online2 August 2001Published inissue 1 A

We report synthesis and optical/structural characterization of new fluorescent rod–coil amphiphiles based on the PEGylated α-cyanostilbene skeleton (12EO-CNMBE and 12EO-CNTFMBE) and their self-assembly behaviors in water. Distinct from the common amphiphilic behavior of nonfluorinated 12EO-CNMBE forming spherical nanostructures, fluorinated 12EO-CNTFMBE has proven to be the first example of a molecular building block that can self-assemble in water into small-dimension, small-aspect-ratio organi

Mannich und mehr: Eine Sequenz aus intramolekularer Redox-, Pinacol-, Mannich- und Michael-Reaktion führt unter Goldkatalyse zu verschiedenartigen Strukturen mit quartären Kohlenstoffzentren, z. B. Spirocyclen, 1-Aminoindanen und anellierten 5,6-Azabicyclen. Die Reaktion zeichnet sich durch vollständige Atomökonomie, hohe Diastereoselektivität und eine erstaunliche Effizienz aus.

Cyclohexylidene-protected diphosphinite-Rh complex A derived from α,α‘-trehalose was treated with acidic resin in methanol to get the unprotected complex B, which is water soluble. Preparation of complexes A−C and their applications for hydrogenations show the problems and prospects of using water as a solvent for these reactions.