이철범 교수

A photo opportunity: A visible-light-excited iridium catalyst delivers electrons from an amine to an organohalide. The electron transfer then induces reductive scission of the carbon–halogen bond, generating the corresponding alkyl, alkenyl, and aryl radical that can undergo cyclization and hydrodehalogenation reactions. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made ava

With their mechanistic novelty and various modalities of reactivity, transition metal unsaturated carbene (alkenylidene) complexes have emerged as versatile intermediates for new reaction discovery. In particular, the past decade has witnessed remarkable advances in the chemistry of metal vinylidenes and allenylidenes, leading to the evolution of a diverse array of new catalytic transformations that are mechanistically distinct from those developed in the previous two decades. This review aims t

The C-H imidation of arenes and heteroarenes has been achieved via visible light induced photocatalysis. In the presence of an iridium(III) photoredox catalyst, the reaction of aromatic substrates with N-chlorophthalimide furnishes the N-aryl products at room temperature through a nitrogen-centered radical mediated aromatic substitution.

Bei Licht betrachtet: Ein durch sichtbares Licht angeregter Iridiumkatalysator überträgt Elektronen von einem Amin auf ein Organohalogenid. Der Elektronentransfer löst daraufhin die reduktive Spaltung der Kohlenstoff-Halogen-Bindung aus und erzeugt das entsprechende Alkyl-, Alkenyl- oder Arylradikal, das Cyclisierungs- und Hydrodehalogenierungsreaktionen eingehen kann. DIPEA=N,N-Diisopropylethylamin.

Cyanine (Cy) dyes are among the most useful organic fluorophores that have found a wide range of applications in single-molecule and super-resolution imaging as well as in other biophysical studies. However, recent observations that blueshifted derivatives of Cy dyes are formed via photoconversion have raised concerns as to the potential artifacts in multicolor imaging. Here, we report the mechanism for the photoconversion of Cy5 to Cy3 that occurs upon photoexcitation during fluorescent imaging

A gem of a couple: The title reaction of terminal alkynes with O and N nucleophiles proceeds in the presence of [{Rh(cod)Cl}2], P(4-FC6H4)3, and 4-picoline N-oxide. Alcohols, amines, and water add to the terminal alkynes to give esters, amides, and carboxylic acids, respectively. The reaction involves formation of a rhodium vinylidene, oxidation to a ketene by oxygen transfer, and nucleophilic addition.

An efficient protocol for the modular synthesis of sulfones and sulfonyl derivatives has been developed utilizing sodium <i>tert</i>-butyldimethylsilyloxymethanesulfinate (TBSOMS-Na) as a sulfoxylate (SO₂ ^2-) equivalent. TBSOMS-Na, easily prepared from the commercial reagents Rongalite™ and TBSCl, serves as a potent nucleophile in <i>S</i>-alkylation and Cu-catalyzed <i>S</i>-arylation reactions with alkyl and aryl electrophiles. The sulfone products thus obtained can under

Transition metal-mediated catalysis routinely enables substrates of multiple π-systems to be efficiently coupled with various carbon nucleophiles along with simultaneous ring formation. This transformation, however, remains unexplored in connection with pericyclic processes. Reported here is a protocol for cycloalkene synthesis based on the merger of rhodium catalysis and a retro-ene reaction. The approach allows alkyne-tethered hydrazones and organoboronic acids to undergo a cascade of addition

Und Sauerstoff dazu: In Gegenwart von [{Rh(cod)Cl}2], P(4-FC6H4)3 und 4-Picolin-N-oxid reagieren terminale Alkine mit O- und N-Nukleophilen (Alkoholen, Aminen und Wasser) zu Estern, Amiden und Carbonsäuren. Die Reaktion verläuft über die Bildung eines Rhodiumvinylidenkomplexes, Oxidation zum Keten durch Sauerstofftransfer und nukleophile Addition. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and ma

Garsubellin A is a meroterpene capable of enhancing the enzyme choline acetyltransferase whose decreased level is believed to play a central role in the symptoms of Alzheimer's disease. Due to the potentially useful biological activity together with the novel bridged and fused cyclic molecular architecture, garsubellin A has garnered substantial synthetic interest, but its absolute stereostructure has been undetermined. We report here the first enantioselective total synthesis of (+)-garsubellin

A tandem approach for the stereoselective allylic reduction has been developed based on a strategy combining the palladium-catalyzed <italic>S</italic>-allylation and the sulfinyl retro-ene reactions.

Abstract Garsubellin A is a meroterpene capable of enhancing the enzyme choline acetyltransferase whose decreased level is believed to play a central role in the symptoms of Alzheimer's disease. Due to the potentially useful biological activity together with the novel bridged and fused cyclic molecular architecture, garsubellin A has garnered substantial synthetic interest, but its absolute stereostructure has been undetermined. We report here the first enantioselective total synthesis of (+)‐ga

Abstract Described here is the rhodium(I)‐catalyzed tandem addition–cyclization of 1,5‐enynes with aryl‐ and alkenylboronic acids. In the presence of triethylamine and catalytic [Rh(OH)(COD)] 2 in methanol, both the terminal and internal alkyne substrates possessing an electron‐deficient alkene undergo inter‐ and intramolecular C−C bond formations to yield alkylidene–cyclobutane products. The reaction proceeds through a series of processes involving generation of an aryl or alkenyl rhodium from