Search results for "Amino acid synthesis"
showing 5 items of 25 documents
Use of gaseous 13NH3 administered to intact leaves of Nicotiana tabacum to study changes in nitrogen utilization during defence induction
2010
Nitrogen-13 (t(1/2) 9.97 m), a radioactive isotope of nitrogen, offers unique opportunities to explore plant nitrogen utilization over short time periods. Here we describe a method for administering (13)N as gaseous (13)NH(3) to intact leaves of Nicotiana tabacum L. (cv Samsun), and measuring the labelled amino acids using radio high-performance liquid chromatography (HPLC) on tissue extract. We used this method to study the effects of defence induction on plant nitrogen utilization by applying treatments of methyl jasmonate (MeJA), a potent defence elicitor. MeJA caused a significant increase relative to controls in key [(13)N]amino acids, including serine, glycine and alanine by 4 h post-…
Yeast interaction on Chardonnay wine composition: Impact of strain and inoculation time.
2022
Abstract It is of great importance to understand the molecular characteristics and substantial chemical transformations due to yeast-yeast interaction. Non-targeted metabolomics was used to unravel must in fermentation composition, inoculated with non-Saccharomyces (NS) yeasts and Saccharomyces cerevisiae (S) for sequential fermentation. ultrahigh-resolution mass spectrometry was able to distinguish thousands of metabolites and provides deep insights into grape must composition allowing better understanding of the yeast-yeast interactome. The dominance of S, characterized by a metabolic richness not found with NS, is dependent on inoculation time and on the yeast species present. Co-inocula…
Ring Expansion of 1,2,3,4-Tetrahydroisoquinolines to Dibenzo[c,f]azonines. An Unexpected [1,4]-Sigmatropic Rearrangement of Nitrile-Stabilized Ammoni…
2014
When the products of a Strecker reaction of 1,2,3,4-tetrahydroisoquinolines with aromatic aldehydes are quaternized with alkyl triflates and subsequently treated with base, a ring expansion to 6,7,8,13-tetrahydro-5H-dibenzo[c,f]azonine-5-carbonitriles takes place. The nine-membered cyclic products can be obtained in good yields (78-89%) in a process involving the [1,4]-sigmatropic rearrangement of a nitrile-stabilized ammonium ylide. The reaction sequence provides a new, simple, and efficient method for the synthesis of these unusual N-heterocycles.
Facile Preparation of 3-Amino-4-(arylamino)-1H-isochromen-1-ones by a New Multicomponent Reaction
2005
Reactions between 2-formylbenzoic acid, various anilines and HCN result in the formation of 3-amino-4-(arylamino)-1H-isochromen-1-ones in high yield. The mechanism of this three-component condensation involves the intermediate formation of an α-aminonitrile and subsequent cyclization through nucleophilic attack of the ortho-carboxylate at the nitrile carbon. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
ChemInform Abstract: Reversal of Asymmetric Induction in Stereoselective Strecker Synthesis on Galactosyl Amine as the Chiral Matrix.
1989
Abstract The reversal of the direction of asymmetric induction in Lewis acid catalyzed Strecker synthesis using the 2,3,4,6-tetra-O-pivaloyl-β-D-galactopyranosyl amine 1 is described. In isopropanol or tetrahydrofuran 1 had given ( R )-diastereomers of the corresponding α-amino nitriles preferably. However, in chloroform in the presence of heterogeneous zinc chloride the same auxiliary alternatively leads to an excess of the ( S )-diastereomers.