Cristina Nevado

Gold-Catalyzed Ethynylation of Arenes

A novel gold-catalyzed ethynylation of aromatic rings with electron-deficient alkynes via gold catalyzed C-H activation of both C(sp)-H and C(sp(2))-H bonds has been developed. This transformation provides aromatic propiolates difficult to prepare by other methods, highlighting the synthetic potential of gold chemistry.

Copper-catalyzed one-pot trifluoromethylation/aryl migration/desulfonylation and C(sp2)-N bond formation of conjugated tosyl amides.

A novel copper-catalyzed one-pot trifluoromethylation/aryl migration/desulfonylation and C(sp(2))-N bond formation with conjugated tosyl amides as starting materials is presented here. The reaction affords α-aryl-β-trifluoromethyl amides bearing a quaternary stereocenter or trifluoromethylated oxindoles in a regioselective manner.

Metal‐Free Aryltrifluoromethylation of Activated Alkenes

Metal-free: The first metal-free aryltrifluoromethylation of activated alkenes has been developed. With this method, trifluoromethylated isoquinolinediones, spirobicycles, oxindoles, and α-aryl-β-trifluoromethylamides were obtained with high control of the regioselectivity.

Cyclization cascades via N-amidyl radicals toward highly functionalized heterocyclic scaffolds.

The addition of a variety of radicals to the double bond of N-(arylsulfonyl)acrylamides can trigger cyclization/aryl migration/desulfonylation cascades via amidyl radical intermediates 2. Herein, we demonstrate the synthetic utility of these intermediates in subsequent C-C and C-X bond-forming events to rapidly build up molecular complexity. First, we describe a regioselective one-pot synthesis of CF3-, SCF3-, Ph2(O)P-, and N3-containing indolo[2,1-a]isoquinolin-6(5H)-ones from N-[(2-ethynyl)arylsulfonyl]acrylamides through a multi-step radical reaction cascade. The process involves the one-pot formation of four new bonds (one C-X, two C-C, and one C-N), a formal 1,4-aryl migration, and desulfonylation of the starting material. Second, we present a one-pot synthesis of 3,3-disubstituted-2-dihydropyridinones from N-(arylsulfonyl)acrylamides and 1,3-dicarbonyl compounds. In this case, a silver-catalyzed radical cascade process involving the sequential formation of two new C-C bonds and one C-N bond, a formal 1,4-aryl migration, and desulfonylation of the starting material explains the regioselective formation of densely functionalized heterocycles in a straightforward manner. Control experiments have unraveled the key intermediates as well as the sequence of individual steps involved in these transformations.

Flexible Gold‐Catalyzed Regioselective Oxidative Difunctionalization of Unactivated Alkenes

Diols, diamines, and aminoalcohols are ubiquitous functionalities in complex organic molecules. From the seminal work of Sharpless and co-workers on the intermolecular osmiumcatalyzed asymmetric dihydroxylation and aminohydroxylation of alkenes, the development of alternative methods to access these privileged motifs has become a priority for synthetic organic chemists. In recent years, palladium catalysts in combination with PhI(OAc)2 as oxidant have been successfully used in the aminooxygenation and diamination of unactivated alkenes both intraand intermolecularly. These transformations rely on the oxidation of Pd to Pd species to facilitate the formation of C X bonds. 5] Coppercatalyzed and also metal-free reactions have been reported although the required acidic media in the later processes might limit its potential application in more elaborated settings [Eq. (1); TFA = trifluoroacetic acid]. Our research group has recently combined the unique carbophilicity of gold complexes with the Au/Au redox catalytic cycles to design new transformations. 9] Surprisingly, though, only one example of gold-catalyzed oxidative diamination of alkenes from ureas has been reported up to date. We envisioned that highly oxidized gold(III) intermediates generated in the presence of oxidants such as Selectfluor or PhI(OAc)2 could trigger the selective oxidative difunctionalization of alkenes [Eq. (2)].

Regio- and Enantioselective Aminofluorination of Alkenes†

Enantio- and regioselective: The intramolecular enantioselective aminofluorination of unactivated olefins was achieved by using a chiral iodo(III) difluoride salt. A highly regioselective aminofluorination of styrenes to access 2-fluoro-2-phenylethanamines was also developed.

Mechanistic insights in gold-stabilized nonclassical carbocations: gold-catalyzed rearrangement of 3-cyclopropyl propargylic acetates.

The reaction of 3-cyclopropyl propargylic carboxylates with Au(I) and Au(III) catalysts affords selectively 5-(E)-alkylidenecyclopentenyl acetates via [3,3]-sigmatropic rearrangement of the carboxylic moiety followed by cyclopropyl ring opening and cyclization. DFT calculations have been performed, supporting a two-step no-intermediate mechanism along the cyclization coordinate. The stereoselective formation of the exocyclic alkenes is kinetically controlled in the first of these events. Although stereospecific in nature through a gold-stabilized nonclassical carbocation, the chirality transfer in these cyclopentannulations is not complete. Computational and experimental evidence is provided for a Au-promoted cyclopropyl ring opening/epimerization/ring closure in both cis- and trans-cyclopropyl settings, which competes with the cyclization event, thus eroding the stereochemical information transfer. When tertiary acetates were used, products of both 1,2- and 1,3-acyloxy migration processes could be isolated, supporting the competitive coexistence of these two pathways along the reaction profile, as suggested also by DFT calculations.

Arylphosphonylation and Arylazidation of Activated Alkenes

Two radical-mediated processes of activated alkenes, namely arylphosphonylation and arylazidation, are described. The difunctionalization of alkenes by a tandem process that involves radical addition, 1,4-aryl migration, and desulfonylation generates α-aryl-β-heterofunctionalized amides bearing a quaternary stereocenter when the substituent on the nitrogen atom is an aryl group. Alternatively, heterooxindoles or spirobicycles can be obtained with excellent regioselectivity in the presence of an alkyl substituent on the nitrogen atom.

Kinase selectivity potential for inhibitors targeting the ATP binding site

UNLABELLED MOTIVATION AND METHOD: Small-molecule inhibitors targeting the adenosine triphosphate (ATP) binding pocket of the catalytic domain of protein kinases have potential to become drugs devoid of (major) side effects, particularly if they bind selectively. Here, the sequences of the 518 human kinases are first mapped onto the structural alignment of 116 kinases of known three-dimensional structure. The multiple structure alignment is then used to encode the known strategies for developing selective inhibitors into a fingerprint. Finally, a network analysis is used to partition the kinases into clusters according to similarity of their fingerprints, i.e. physico-chemical characteristics of the residues responsible for selective binding. RESULTS For each kinase the network analysis reveals the likelihood to find selective inhibitors targeting the ATP binding site. Systematic guidelines are proposed to develop selective inhibitors. Importantly, the network analysis suggests that the tyrosine kinase EphB4 has high selectivity potential, which is consistent with the selectivity profile of two novel EphB4 inhibitors. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.

Stereoselective Synthesis of Highly Functionalized Indanes and Dibenzocycloheptadienes through Complex Radical Cascade Reactions

Two highly stereoselective radical-mediated syntheses of densely functionalized indanes and dibenzocycloheptadienes from ortho-vinyl- and ortho-vinylaryl-substituted N-(arylsulfonyl)-acrylamides, respectively, are presented here. The chemoselective addition of in situ generated radicals (X(·)) onto the styrene moieties triggers an unprecedented reaction cascade, resulting in the formation of one new C-X bond and two new C-C bonds, a formal 1,4-aryl migration, and the extrusion of SO2 to generate an amidyl radical intermediate. This intermediate, upon H abstraction, leads to the observed 5- and 7-membered ring carbocyclic products, respectively, in a highly efficient manner.