Showing papers by "Armando Córdova published in 2010"
Book•
01 Jan 2010
TL;DR: Asymmetric Bifunctional Catalysis Using Heterobimetallic and Multimetallic Systems in Enantioselective Conjugate Additions and asymmetric Epoxidations of a,ss-Unsaturated Carbonyl Compounds.
Abstract: 1 Rhodium- and Palladium-Catalyzed Asymmetric Conjugate Additions 2 Cu- and Ni-Catalyzed Conjugated Additions of Organozincs and Organoaluminums to a,ss-Unsaturated Carbonyl Compounds 3 ECAs of Organolithium Reagents, Grignard Reagents, and Examples of Cu-Catalyzed ECAs 4 Asymmetric Bifunctional Catalysis Using Heterobimetallic and Multimetallic Systems in Enantioselective Conjugate Additions 5 Enamines in Catalytic Enantioselective Conjugate Additions 6 Iminium Activation in Catalytic Enantioselective Conjugate Additions 7 Organocatalytic Enantioselective Conjugate Additions of Heteroatoms to a,ss-Unsaturated Carbonyl Compounds 8 Domino Reactions Involving Catalytic Enantioselective Conjugate Additions 9 Asymmetric Epoxidations of a,ss-Unsaturated Carbonyl Compounds 10 Catalytic Asymmetric Baylis?Hillman Reactions and Surroundings
93 citations
TL;DR: The first examples of one-pot highly chemo- and enantioselective dynamic kinetic asymmetric transformations (DYKATs) involving alpha,beta-unsaturated aldehydes and propargylated carbon acids are presented.
Abstract: Dynamic kinetic asymmetric transformation (DYKAT) by combined amine- and transition-metal-catalyzed enantioselective cycloisomerization
91 citations
TL;DR: It is reported that inorganic ammonium ions, NH(4)(+), and carbonate ions, CO(3)(2-), are also efficient catalysts for the aldol condensation of carbonyl compounds, and shows, in particular, that common ones, such as ammonium and Carbonate salts, might even play important roles in their chemical transformations.
Abstract: In natural environments such as atmospheric aerosols, organic compounds coexist with inorganic salts but, until recently, were not thought to interact chemically. We have recently shown that inorganic ammonium ions, NH4+, act as catalysts for acetal formation from glyoxal, a common atmospheric gas. In this work, we report that inorganic ammonium ions, NH4+, and carbonate ions, CO32−, are also efficient catalysts for the aldol condensation of carbonyl compounds. In the case of NH4+ this was not previously known, and was patented prior to this article. The kinetic results presented in this work show that, for the concentrations of ammonium and carbonate ions present in tropospheric aerosols, the aldol condensation of acetaldehyde and acetone could be as fast as in concentrated sulfuric acid and might compete with their reactions with OH radicals. These catalytic processes could produce significant amounts of polyconjugated, light-absorbing compounds in aerosols, and thus affect their direct forcing on climate. For organic gases with large Henry's law coefficients, these reactions could also result in a significant uptake and in the formation of secondary organic aerosols (SOA). This work reinforces the recent findings that inorganic salts are not inert towards organic compounds in aerosols and shows, in particular, that common ones, such as ammonium and carbonate salts, might even play important roles in their chemical transformations.
77 citations
TL;DR: The novel methodology is based on the combination of organic acid-catalyzed esterification or etherification and photochemical thiol-ene click derivatization of a heterogeneous polysaccharide to allow for a highly modular and metal free surface modification of solidpolysaccharides.
Abstract: A simple and direct method for derivatization of solid polysaccharides is presented. The novel methodology is based on the combination of organic acid-catalyzed esterification or etherification and photochemical thiol-ene click derivatization of a heterogeneous polysaccharide. The solid cellulose was "organoclick" modified with aryl, alkyl and polyester groups, respectively. The modification allows for a highly modular and metal free surface modification of solid polysaccharides.
77 citations
TL;DR: A one-pot highly chemo- and enantioselective catalytic domino oxa-Michael/carbocyclization between α,β-unsaturated aldehydes and propargylic alcohols is presented.
Abstract: A one-pot highly chemo- and enantioselective catalytic domino oxa-Michael/carbocyclization between α,β-unsaturated aldehydes and propargylic alcohols is presented. This dynamic kinetic transforma ...
74 citations
TL;DR: In this article, an asymmetric synthesis of Maraviroc (UK-427,857), a chemochine receptor 5 (CCR-5) receptor antagonist, based on an expeditious organocatalytic enantioselective assembly of the chiral β-amino aldehyde key fragment is presented.
Abstract: The asymmetric synthesis of Maraviroc (UK-427,857), a chemochine receptor 5 (CCR-5) receptor antagonist, based on an expeditious organocatalytic enantioselective assembly of the chiral β-amino aldehyde key fragment is presented. The reactions were performed on a gram-scale and allow for the rapid construction of new Maraviroc analogues.
49 citations
TL;DR: In this paper, the first example of a highly enantioselective organocatalytic aziridination of α-substituted α,β-unsaturated aldehydes is presented.
Abstract: The first example of a highly enantioselective organocatalytic aziridination of α-substituted α,β-unsaturated aldehydes is presented. The reaction is catalyzed by simple chiral amines and gives acc ...
45 citations
TL;DR: In this paper, a highly enantioselective catalytic route to carbamate and benzoate-protected β-amino aldehydes and βamino acids is presented.
23 citations
TL;DR: In this paper, a highly diastereoselective pyrrolidine-promoted dibromination of alkenes by combination of NBS and succinimide is presented.
22 citations
TL;DR: Nonlinear effects in asymmetric amino acid catalysis by multiple interconnected stereoselective catalytic networks are studied.
Abstract: Nonlinear effects in asymmetric amino acid catalysis by multiple interconnected stereoselective catalytic networks
8 citations
21 Jun 2010
TL;DR: Dynamic kinetic asymmetric transformation (DYKAT) as discussed by the authors combines amine and transition metal catalyzed enantioselective cycloisomerization to achieve dynamical asymmetric transformations.
Abstract: Dynamic kinetic asymmetric transformation (DYKAT) by combined amine- and transition-metal-catalyzed enantioselective cycloisomerization
TL;DR: Asymmetric bifunctional catalysis using heterobimetallic and multimetallic systems in enantioselective conjugate additions was studied in this paper, where the authors proposed a method to solve this problem.
Abstract: Asymmetric bifunctional catalysis using heterobimetallic and multimetallic systems in enantioselective conjugate additions
TL;DR: Inorganic ammonium salts catalyze the direct aldol reaction between unmodified ketones and aldehydes to furnish the corresponding β-hydroxy ketones in aqueous media as discussed by the authors.
Abstract: Inorganic ammonium salts catalyze the direct aldol reaction between unmodified ketones and aldehydes to furnish the corresponding β-hydroxy ketones in aqueous media. The reactions are highly chemoselective and operationally simple.
TL;DR: In this paper, a highly chemo-and enantioselective organocatalytic addition of fluorocarbon nucleophiles, such as 1-fluoro-bis(phenylsulfonyl)methane, toα,β-unsaturated aldehydes is presented.
Abstract: A highly chemo- and enantioselective organocatalytic addition of fluorocarbon nucleophiles, such as 1-fluoro-bis(phenylsulfonyl)methane, toα,β-unsaturated aldehydes is presented (see scheme). The reactions are catalyzed by simple chiral amines and give access to optically active fluorine derivatives in good yields and up to 95 % ee. Notably, the methodology can be applied to the formation of a chiral quaternary carbon center bearing a fluorine atom with high enantioselectivity.
TL;DR: In this paper, a new type of chiral Mo complex (see scheme; TBS=tert-butyldimethylsilyl, X=Cl, Br, I) was employed for the selective synthesis of Zalkenes.
Abstract: Stopping the gap: A notable shortcoming in olefin metathesis chemistry was the lack of methods for the selective synthesis of Z?alkenes. A breakthrough has now been achieved by the employment of a new type of chiral Mo complex (see scheme; TBS=tert-butyldimethylsilyl, X=Cl, Br, I). The first examples of the titled reactions are discussed.
TL;DR: In this paper, a highly diastereoselective pyrrolidine-promoted dibromination of alkenes by combination of NBS and succinimide is presented.
Abstract: A highly diastereoselective pyrrolidine-promoted dibromination of alkenes by combination of NBS and succinimide is presented. The pyrrolidine-mediated dibromination of alkenes is higly anti-selective and gives the corresponding products in moderate to high yields and up to >25:1 dr.