Fernando López-Ortiz

Bio: Fernando López-Ortiz is an academic researcher from University of Almería. The author has contributed to research in topics: Transition metal carbene complex & Cycloaddition. The author has an hindex of 13, co-authored 41 publications receiving 405 citations. Previous affiliations of Fernando López-Ortiz include Spanish National Research Council & University of Oviedo.

Alkenyl Fischer Carbene Complexes and α,β‐Unsaturated Imine Derivatives: Synthesis of Azepines and Mechanistic NMR Studies

Abstract: 4-Amino-1-azadienes 1 react with α,β-unsaturated Fischer carbene complexes at −40°C to give stereoselectively a variety of substituted 3H-4,5-dihydroazepines 3; similarly, 1-hydroxy-1-azadienes (α,β-unsaturated oximes) 6 afforded the corresponding azepine derivatives 7. Chiral, nonracemic carbene complexes 11 gave azepines 12–13 (d.e. = 40–44%) upon reaction with oxime 6a; the major isomers were obtained in a diastereomerically and enantiomerically pure form (45–50% overall yield) after crystallization. An X-ray structure of 12a allowed assignment of the absolute stereochemistry. The acid hydrolysis of azepines synthesized provided racemic and enantiomerically pure 1,6-dicarbonyl compounds (±)-5, (±)-9, and (–)-14, as well as diol (–)-15. The mechanism of the reaction of 1 and 2 was investigated by multinuclear (1H, 13C, 15N, and 183W) NMR characterization of four intermediates (A, B, C, and D) at low temperature. The experimental sequence of events involves: i) 1,2-nucleophilic addition of the unsubstituted imine nitrogen of 1 to the metal carbene function (zwitterion A, −60°C), ii) cyclization to the seven-membered ring with 1,2-migration of the pentacarbonyl metal (zwitterion B, −40°C), iii) reductive elimination and coordination of the metal to the amine nitrogen (intermediate C, −40°C), and iv) thermal decomplexation and tautomerization (intermediate D and compound 3, above −20°C).

Synthesis of Polyfunctionalized 1-Aminobuta-1,3-dienes by Addition of Dimethyl Acetylenedicarboxylate to (Z)-.beta.-Enamino-.lambda.5-Phosphazenes. Configurational and Conformational Analysis Based on NOE Data, nJPX Coupling Constant, X-ray Structures, and Semiempirical Calculations

Abstract: DMAD adds regioselectivelly to N-acyl-(Z)-β-enaminophosphazenes through the β position with high stereoselectivity. The stereochemistry and conformation of the products (2) and (4) in solution have been elucida- ted based upon NOE experiments and n J PX (n=1-4, X=C, H) data. Large negative 4 J PH coupling constants from a predominant π contribution were observed from which conformational information could be derived. 3 J PC values are positive and follow the expected Karplus model, and values 2 J PC show a large stereochemical dependence. The activation energies for the isomerization of the C=C double bond as well as for the rotation around the C-N single bond of the enamine linkage have been calculated. The crystal structures of (Z)-1-benzoyl-3-[(Z)-1,2-bis(me- thoxycarbonyl)vinyl]-2,2-diphenyl-4-(p-tolyl)-1,5-diaza-2λ 5 -phophapenta-1,3-diene (2a) and E,Z derivative (2b) have been elucidated by single- crystal X-ray diffraction. Calculated conformations by MM and PM3 met- hods were in good agreement with the experimental observations

Novel syntheses of azetidines and azetidinones.

Abstract: 2.1.5. Electrophilic Attack on CdC 3994 2.1.6. NH Insertions in Diazo Compounds 3994 2.1.7. Pd Catalyzed Cyclizations 3994 2.2. Cyclizations by C-C Bond formation 3995 2.2.1. Nucleophilic Displacement of Halides 3995 2.2.2. Cyclizations Involving CdO Group 3995 2.3. Cycloadditions 3996 2.4. Ring Rearrangements 3997 2.4.1. Rearrangements of Four-Membered Rings 3997 2.4.2. Rearrangements of Larger Rings 3998 2.5. Reduction of Azetidin-2-ones 3998 2.6. Miscellaneous Syntheses 3999 2.7. Important Classes of Compounds 4000 2.7.1. Natural Products 4000 2.7.2. Azetidine Carboxylic Acids 4001 2.7.3. Exomethylene Azetidines 4002 2.7.4. Ligands for Metal-Catalyzed Reactions and Chiral Auxiliaries 4003

Fischer Carbene Complexes in Organic Synthesis: Metal-Assisted and Metal-Templated Reactions

Abstract: The formal combination of a carbene and an organometallic fragment yields carbene complexes. They are commonly classified as Fischerand Schrock-type complexes. While Schrock-type compounds (first described in the early 1970s) play an important role in olefin metathesis (acknowledged by the Nobel Prize 20051), Fischer carbene complexes, which were first reported in 19642a and 1965,2b have been developed into powerful reagents for organic synthesis.3 This review concentrates on group 6 metal carbene complexes with a special focus on chromium complexes since, because of their balance of reactivity and stability combined with easy accessibility (see below), they are the most prominent members of the Fischer carbenes and have found the broadest application. While most of the recent chemistry of Fischer carbene complexes has been periodically summarized during the last 5-10 years,4 this review, apart from the basic characteristics of Fischer carbene complexes in the introductory part, will focus on the developments since the mid1990s. The literature is covered up to April 2009.