Showing papers by "Armando Córdova published in 2015"

Highly Enantioselective Control of Dynamic Cascade Transformations by Dual Catalysis : Asymmetric Synthesis of Polysubstituted Spirocyclic Oxindoles

Abstract: The highly enantioselective (up to >99.5:0.5 er) synthesis of polysubstituted spirocyclic oxindoles with four new contiguous stereocenters, including the spiro all-carbon quaternary center, is d ...

Abiotic synthesis of amino acids and self-crystallization under prebiotic conditions

Abstract: Building on previous research on the origin and homochirality of life, this study focuses on analyses profiling important building blocks of life: the natural amino acids. The spark discharge variation of the iconic Miller experiment was performed with a reducing gas mixture of ammonia, methane, water and hydrogen. Amino acid analysis using liquid chromatography coupled with tandem mass spectrometry after pre-column derivatizaiton revealed the generation of several amino acids including those essential for life. Re-crystallization of the synthetic products and enantiomeric ratio analysis were subsequently performed. Results from liquid chromatography coupled with either fluorescent detector or tandem mass spectrometry after pre-column derivatization with chiral reagent revealed spontaneous and effective asymmetric resolution of serine and alanine. This work describes a useful analytical platform for investigation of hypotheses regarding the origin and homochirality of amino acids under prebiotic conditions. The formation of numerous amino acids in the electric discharge experiment and the occurrence of high enantiomeric ratios of amino acids in re-crystallization experiment give valuable implications for future studies in unraveling fundamental questions regarding origins and evolution of life.

Selective Access to All Four Diastereomers of a 1,3-Amino Alcohol by Combination of a Keto Reductase- and an Amine Transaminase-Catalysed Reaction

Abstract: The biocatalytic synthesis of chiral amines has become a valuable addition to the chemists' tool-box. However, the efficient asymmetric synthesis of functionalised amines bearing more than one ster ...

The Use of Porous Palladium(II)-polyimine in Cooperatively- catalyzed Highly Enantioselective Cascade Transformations

Abstract: Porous organic polymers have prospects as functional substrates for catalysis, with quite dif- ferent molecular properties from inorganic sub- strates. Here we disclose for the first time that porous palladium(II)-polyimines are excellent cata- lysts for cooperatively catalyzed and enantioselec- tive cascade reactions. In synergy with a chiral amine co-catalyst, polysubstituted cyclopentenes and spirocyclic oxindoles, including the all-carbon quaternary stereocenter, were synthesized in high yields. High diastereo- and enantioselectivities were achieved for these dynamic kinetic asymmetric transformations (DYKAT) of enals with propargylic nucleophiles.

Combined heterogeneous metal/organic catalysts for eco-friendly synthesis

Abstract: The interplay and synergistic cooperation between homogeneous and heterogeneous catalyst systems is of utmost importance in nature. It is also applied in chemical synthesis. Here, it can allow for ...

Efficient synthesis of amines and amides from alcohols and aldehydes by using cascade catalysis

Abstract: The present invention relates generally to an eco-friendly methodology for the conversion of alcohols and aldehydes to amines and amides using an integrated enzyme cascade system with metal-and organocatalysis. More specifically, the present invention relates to synthesis of capsaicinoids starting from vanillin alcohol and using a combination of an enzyme cascade system and catalysts. Furthermore, the method also relates to synthesis of capsaicinoids derivatives starting from vanillin alcohol derivatives and using a combination of an enzyme cascade system and catalysts.

Synthesis of amides and amines from aldehydes or ketones by heterogeneous metal catalysis

Abstract: This invention concerns the first mild and efficient synthesis of primary amines and amides from aldehydes or ketones using a heterogeneous metal catalystand amine donor. The initial heterogeneous metal- catalyzed reaction between the carbonyl and the amine donor components is followed up with the addition of a suitable acylating agent component in one-pot. Hence, the present invention provides a novel catalytic one-pot three-component synthesis of amides. Moreover, the integration of enzyme catalysis allows for eco-friendly one-pot co-catalytic synthesis ofamides from aldehyde and ketone substrates, respectively. The process can be applied to the co-catalytic one-pot three-component synthesis of capsaicin and its analogues from vanillin or vanillyl alcohol. It can also be applied for asymmetric synthesis. In the present invention, a novel co-catalytic reductive amination/dynamic kinetic resolution (dkr) relay sequence for the asymmetric synthesis of optically active amides from ketones is disclosed. Moreover, implementation of a catalytic reductive amination/kinetic resolution (kr) relay sequence produces the corresponding optically active amide product and optical active primary amine product with the opposite stereochemistry from the starting ketones.

Enantioselective Heterogeneous Synergistic Catalysis for Asymmetric Cascade Transformations.

Abstract: A modular design for a novel heterogeneous synergistic catalytic system, which simultaneously activates the electrophile and nucleophile by the combined activation modes of a separate metal and non ...