Alberto Avenoza

Investigations of La Rioja terroir for wine production using 1H NMR metabolomics.

In this study, La Rioja wine terroir was investigated by the use of (1)H NMR metabolomics on must and wine samples. Rioja is a small wine region in central northern Spain which can geographically be divided into three subareas (Rioja Alta, Rioja Baja, and Rioja Alavesa). The winemaking process from must, through alcoholic and malolactic fermentation, was followed by NMR metabolomics and chemometrics of nine wineries in the Rioja subareas (terroirs). Application of interval extended canonical variate analysis (iECVA) showed discriminative power between wineries which are geographically very close. Isopentanol and isobutanol compounds were found to be key biomarkers for this differentiation.

A thorough study on the use of quantitative 1H NMR in Rioja red wine fermentation processes.

In this study, we focused our attention on monitoring the levels of important metabolites of wine during the alcoholic and malolactic fermentation processes by quantitative nuclear magnetic resonance (qNMR). Therefore, using (1)H NMR, the method allows the simultaneous quantification of ethanol, acetic, malic, lactic, and succinic acids, and the amino acids proline and alanine, besides the ratio proline/arginine through fermentation of must of grapes corresponding to the Tempranillo variety. Each (1)H NMR spectrum gives direct and visual information concerning these metabolites, and the effectiveness of each process was assessed and compared by carrying out analyses using infrared spectroscopy to ethanol and acetic acid. The quantitative data were explained with the aid of chemometric algorithms.

Enantioselective synthesis of (S)- and (R)-α-methylserines: application to the synthesis of (S)- and (R)-N-Boc-N,O-isopropylidene-α-methylserinals

Abstract This report describes the synthesis of enantiomerically pure ( S )- and ( R )-α-methylserines on a multigram scale, starting from the Weinreb amide of 2-methyl-2-propenoic acid and using a stereodivergent synthetic route that involves a Sharpless asymmetric dihydroxylation reaction. As a synthetic application of these quaternary α-amino acids, they were used as starting materials in the synthesis of the well-known valuable homochiral ( S )- and ( R )- N -Boc- N , O -isopropylidene-α-methylserinal building blocks.

Synthesis of new conformationally rigid phenylalanine analogues

Abstract The reactivity of (Z)-2-phenyl-4-benzylidene-5(4H)-oxazolone 1 as dienophile in the Diels-Alder reaction with 1,3-butadiene and 2,3-dimethyl-1,3-butadiene is studied. The adducts obtained starting from the cycloaddition of 1 with both dienes are converted, through simple reactions into the conformationally restricted cyclic amino acids cis-1-amino-2-phenylcyclohexanecarboxylic acid 6 and 1-amino-c-4,c-5-dimethyl-t-2-phenyl-r-1-cyclohexanecarboxylic acid 10 , analogues of phenylalanine.

SYNTHESIS OF A NEW ENANTIOMERICALLY PURE CONSTRAINED HOMOSERINE

Abstract The use of the Diels-Alder reaction between 1,3-butadiene and chiral 2-acetamidoacrylates as the key step followed by stereocontrolled transformations allows the synthesis of (1 S , 3 R )-1-amino-3-hydroxycyclohexanecarboxylic acid, a new type of constrained homoserine, with an excellent overall yield.

New synthesis of 7-azabicyclo[2.2.1]heptane-1-carboxylic acid

Abstract This report describes a new synthetic route to 7-azabicyclo[2.2.1]heptane-1-carboxylic acid (Ahc), a constrained proline analogue, in which the key step is the Diels–Alder reaction using methyl 2-benzamidoacrylate as dienophile.

Asymmetric synthesis of all isomers of α-methyl-β-phenylserine

Abstract This report describes the synthesis of enantiomerically pure (2 R ,3 R )-, (2 R ,3 S )-, (2 S ,3 S )- and (2 S ,3 R )-2-amino-3-hydroxy-2-methyl-3-phenylpropanoic acids, four quaternary α-amino acids, using a stereodivergent synthetic route and starting from ( S )- and ( R )- N -Boc- N , O -isopropylidene-α-methylserinals. The key step involves the asymmetric Grignard additions to the above chiral aldehydes, in which high levels of asymmetric induction are observed.

Synthesis of the four d,l-pairs of 2-amino-3-phenylnorbornane-2-carboxylic acids II. The use of 5(4H)-oxazolones as dienophiles.

Abstract The Diels-Alder reaction between both geometric isomers (Z)- or (E)-2-phenyl-4-benzylidene-5(4H)-oxazolone and cyclopentadiene is studied. The cycloadducts are converted into the aminoacids through simple reactions allowing the synthesis of the four d,l-pairs of 2-amino-3-phenylnorbornane-2-carboxylic acids.

A straightforward synthesis of both enantiomers of α-vinylalanine and α-ethynylalanine

Abstract This report describes the synthesis of enantiomerically pure ( S )- and ( R )-α-vinylalanines and ( S )- and ( R )-α-ethynylalanines, four quaternary α-amino acids, using a straightforward synthetic route and starting from ( S )- and ( R )- N -Boc- N,O -isopropylidene-α-methylserinals.

Reactivity of (Z)-4-arylidene-5(4H)-oxazolones: [4+2] cycloaddition versus [4+3] cycloaddition/nucleophilic trapping

Abstract The use of different aluminum derivatives in the reaction between cyclopentadiene and ( Z )-2-phenyl-4-arylidene-5(4 H )-oxazolones, and in particular the use of different equivalents of the reagent, allows the modulation of the synthesis of the norbornane skeleton by a [4+2] cycloaddition or the more interesting bicyclo[3.2.1]octane framework by a [4+3] cycloaddition followed by nucleophilic trapping of the ionic dipole cycloadduct with cyclopentadiene.