Chiral, Sterically Demanding N-Heterocyclic Carbenes Fused into a Heterobiaryl Skeleton: Design, Synthesis, and Structural Analysis
摘要:
A series of Cu(I), Ag(I), and Au(I) complexes incorporating a new family of imidazopyridin-3-ylidene ligands substituted by a diphenylpyrrolidino group at N(1) and aryl groups at C(5) has been synthesized and their structures determined by X-ray diffraction analysis. This structural study has revealed an extremely high steric protection of the metal center by the bulky heterobicyclic carbenes, while the inversion at the exocyclic N(sp(3)) atom provides a remarkable flexibility.
Regio- and Enantioselective Allylation of Phenols<i>via</i>Decarboxylative Allylic Etherification of Allyl Aryl Carbonates Catalyzed by (Cyclopentadienyl)ruthenium(II) Complexes and Pyridine-Hydrazone Ligands
作者:Léo Egger、Cecilia Tortoreto、Thierry Achard、David Monge、Abel Ros、Rosario Fernández、José M. Lassaletta、Jérôme Lacour
DOI:10.1002/adsc.201500534
日期:2015.10.12
(Cyclopentadienyl)tris(acetonitrile)ruthenium hexafluorophosphate [CpRu(CH3CN)3][PF6] in combination with pyridine-hydrazone ligands efficiently catalyzes the asymmetric decarboxylative allylic rearrangement of allylarylcarbonates. Formation of CO bonds with high regio- and enantioselectivity ratios (up to 95:5 and 98% ee) is obtained. Good stereocontrol of the pseudotetrahedral geometry of the CpRu
Phosphino Hydrazones as Suitable Ligands in the Asymmetric Suzuki–Miyaura Cross-Coupling
作者:Abel Ros、Beatriz Estepa、Antonio Bermejo、Eleuterio Álvarez、Rosario Fernández、José M. Lassaletta
DOI:10.1021/jo300548z
日期:2012.5.18
Phosphino hydrazones derived from C2-symmetric hydrazines exhibit excellent catalytic activity and provide good enantioselectivities in the asymmetric Suzuki–Miyaura cross-coupling to axially chiralbiaryls, in particular for the most challenging reactions of monocyclic, functionalized aryl bromides and triflates. X-ray analysis of preformed [Pd(P/N)Cl2] precatalysts [(P/N) = phosphino hydrazone] revealed
Design and synthesis of new bis-hydrazones and pyridine bis-hydrazones: application in the asymmetric Diels-Alder reaction
作者:David Monge、Antonio Bermejo、Juan Vázquez、Rosario Fernández、José M. Lassaletta
DOI:10.3998/ark.5550190.0014.205
日期:——
The design of two different types of new chiral bis -hydrazones 5 (bidentate N,N ligands, type A ) and pyridinebis-hydrazones 7 ('pincer' N,N,N ligands, type B) is discussed. Preliminary results on the copper(II)-catalyzed Diels-Alderreaction of N-(E)-crotyloxazolidin-2-one ( 8) with cyclopentadiene ( 9) revealed that the (2 S,6 S)-2,6-diphenylpiperidine C2-symmetric substructure in pyridine bis-hydrazone
Studies on Stereoselective [2+2] Cycloadditions between N,N-Dialkylhydrazones and Ketenes
作者:Eloísa Martín-Zamora、Ana Ferrete、José M. Llera、Jesús M. Muñoz、Rafael R. Pappalardo、Rosario Fernández、José M. Lassaletta
DOI:10.1002/chem.200400452
日期:2004.12.3
chiral, non-racemic N,N-dialkylhydrazones 1 and functionalized ketenes constitute an efficient methodology for the stereoselective construction of the beta-lactam ring. The potential for fine tuning of the dialkylamino auxiliary structure, the availability of a high-yielding deprotection method for the release of the free azetidinones, and the high thermal and chemical stability of hydrazones as N-dialkylamino
Glyoxal bis-hydrazones: a new family of nitrogen ligands for asymmetric catalysis
作者:José M. Lassaletta、Manuel Alcarazo、Rosario Fernández
DOI:10.1039/b314249c
日期:——
The introduction of C2-symmetric dialkylamino substructures in chiral non-racemic glyoxal bis-hydrazones such as 9 appears as the key design element for this novel ligand class, as shown in the highly enantioselective copper(II)-catalyzed Diels–Alder reaction.