Iodine recycling via 1,3-migration in iodoindoles under metal catalysis

3-Substituted (indol-2-yl)-α-allenols show divergent patterns of reactivity under metal catalysis. An unprecedented intramolecular 1,3-iodine migration is described. © 2013 The Royal Society of Chemistry.Peer Reviewe

Organometallic catalysis for applications in radical chemistry and asymmetric synthesis

Two organometallic catalysis studies are presented. The first one deals with the development of a new catalytic agent based on the mixture of a hydride and an iron salt to trigger efficient radical cyclization processes. In a second line of research, we have shown that the use of chiral anions can outperform chiral ligands in a carbocyclization reaction and a 2 + 2 + 2 cycloaddition

Halocyclization of o-(Alkynyl)styrenes. Synthesis of 3-Halo-1H-indenes

Junta de Castilla y Leon (BU021A09 and GR-172), Ministerio de Educacion y Ciencia (MEC), FEDER (CTQ2007-61436/BQU and CTQ2009-09949/BQU), MEC (FPU grant), Juan de la Cierva, Ramon y Cajal and "Young Foreign Researchers" (SB2009-0186) contract

Construction of spirocarbocycles via gold-catalyzed intramolecular dearomatization of naphthols.

A highly efficient, gold-catalyzed intramolecular dearomatization reaction of naphthols via 5-endo-dig cyclization is described. This facile and direct approach furnishes spirocarbocycles in excellent yields under mild conditions

'Diastereoselective Carbocyclization of 1,6-Heptadienes Triggered by Rhodium-Catalyzed Activation of an Olefinic C-H Bond'

The use of α,ω‐dienes as functionalization reagents for olefinic carbon–hydrogen bonds has been rarely studied. Reported herein is the rhodium(I)‐catalyzed rearrangement of prochiral 1,6‐heptadienes into [2,2,1]‐cycloheptane derivatives with concomitant creation of at least three stereogenic centers and complete diastereocontrol. Deuterium‐labeling studies and the isolation of a key intermediate are consistent with a group‐directed C-H bond activation, followed by two consecutive migratory insertions, with only the latter step being diastereoselective

Synthesis of Functionalized Spiro-Heterocycles by Sequential Multicomponent Reaction/Metal Catalyzed Carbocylizations from Simple β-Ketoesters and Amides

International audienceA new strategy from simple cyclic β-ketoesters or amides involving a selective three-component reaction and a ring closing metathesis or a palladium catalyzed carbocyclization in a sequential fashion to access spiro-heterocycles is reported. This expedient two-step sequence generates compounds of significant molecular complexity and high synthetic and biological relevance from simple and readily available starting materials

A fast, efficient and simple method for the synthesis of cyclic alkenyl fluorides by a fluorinative carbocyclization reaction

Tetrafluoroboric acid promotes a fluorinative carbocyclization reaction to give cyclic alkenyl fluorides in a process where the incorporation of the fluorine atom occurs through the nucleophilic addition of a fluoride anion.</p

Development of iron catalysts for hydrogenation and polymerization

Im Rahmen der vorliegenden Arbeit wurden eine Reihe von neuen, einfach herzustellenden Eisenhydrierkatalysatoren eingeführt. Verschiedenste Aspekte dieser neuen Hydrierkatalysatoren wie Eisenquelle, Aktivierungsmittel, Substrate und Effizienz wurden untersucht. Ein ligandfreier Katalysator, hergestellt aus einer Eisen(II)chlorid-Suspension aktiviert mit Diisobutylaluminiumhydrid (DIBAH), weist die grösste Aktivität auf. Alle Arten von C-C-Doppelbindungen wie mono-, di- oder trisubstituierte, acyclische oder cyclische, isolierte oder konjugierte Doppelbindungen sowie Alkine werden von diesem Katalysator unter milden Bedingungen (3 bar Wasserstoffdruck, Raumtemperatur) in kurzer Zeit quantitativ hydriert. Sowohl TON wie auch TOF steigen mit zunehmender Menge Aktivierungsmittel, bis bei einem Verhältnis FeCl2/DIBAH 1:8 mit TON = 1900 und TOF = 125 h-1 der effizienteste Katalysator erhalten wird. Mit Ausnahme von Ethern und Aminen verhindert die Verwendung eines starken Reduktionsmittels zur Aktivierung die Hydrierung von funktionalisierten Olefinen. In Abwesenheit von Wasserstoff H2 konnte katalytische Aktivität für Alkinpolymerisierungs- und Alkincyclotrimerisierungsreaktionen nachgewiesen werden. Ferner kann dieser Katalysator zur Polymerisierung von Acetylen eingesetzt werden. Bei dem Versuch, die in diesen Fällen katalytisch aktive Spezies zu identifizieren fand man einen homogenen Präkatalysator, welcher erstaunliche Effizienz aufweist (TOF > 340 h-1). Abgeleitet von der angenommenen Struktur dieses Präkatalysators wurden eine Reihe von Allylbenzylether synthetisiert, welche als Liganden getestet wurden. Die entsprechenden Katalysatoren, erhalten durch Aktivierung mit Alkyllithiumreagenzien, weisen Alkenhydrier- und Ethylenoligomerisierungsaktivität auf.In the scope of this work, a series of new, easy to prepare iron hydrogenation catalysts have been introduced. Different aspects of this new hydrogenation catalysts such as iron source, activation reagent, substrates and efficiency were investigated. A ligand-free catalyst, prepared from an iron(II) chloride suspension activated with diisobutylaluminiumhydride (DIBAH), showed the highest activity. With this catalyst all kind of C-C double bonds like mono-, di- or trisubstituted, acyclic or cyclic, isolated or conjugated double bonds as well as alkynes were hydrogenated quantitatively under mild conditions (3 bar hydrogen pressure, room temperature) within short time. Both TON and TOF scale with the added amount of activation reagent up to a 1:8 FeCl2/DIBAH ratio furnishing the most active catalyst with TON = 1900 and TOF = 125 in this case. With the exception of ethers and amines, the use of strong reducing agents as activators prevents the hydrogenation of functionalized olefins. In absence of hydrogen H2, catalytic activity for alkyne polymerization and cyclotrimerization was observed. Furthermore, this catalyst is able to promote the polymerization of acetylene. Attempts to identify the catalytic active species led to the development of a homogeneous precatalyst showing an amazing efficiency (TOF > 340 h-1). Derived from the assumed structure of this precatalyst, a series of allylbenzylethers were synthesized and tested as ligands. The corresponding catalysts, obtained by activation with alkyllithium reagents, display alkene hydrogenation and ethylene oligomerization activity