27300-27-2Relevant academic research and scientific papers
Synthesis of 1-piperideine-6-carboxylic acid produced by L-lysine-ε-aminotransferase from the Streptomyces clavuligerus gene expressed in Escherichia coli
Wu, Mei-Li,Chen, Jun-Hao,Ho, Chi-Tang,Huang, Tzou-Chi
, p. 1767 - 1772 (2007)
The gene (laf) encoding L-lysine ε-aminotransferase (LAT) in Streptomyces clavuligerus was cloned and expressed in Escherichia coli. Nucleotide sequence analysis of lat predicted a single open reading frame (ORF) of 1371 bp, encoding a polypeptide of 457 amino acids with calculated molecular mass of 49.89 kDa. S. clavuligerus LAT was grouped into aminotransferase subfamily II of a family on the basis of sequence homology. A model system composed of the recombinant LAT in phosphate buffer was set up to study the biosynthesis of 2-acetyltetrahydropyridine. Lysine was found to be transformed to 1-piperideine-6-carboxylic acid. 2-Acetyltetrahydropyridine was characterized from the mixture of 1-piperideine-6-carboxylic acid and methylglyoxal. For the first time, we demonstrated that the L-lysine ε-aminotransferase is responsible for the formation of 1-piperideine-6-carboxylic acid, which may react with methylglyoxal to generate the acylated N-heterocyclic odorant 2-acetyltetrahydropyridine.
METHOD FOR SYNTHESISING 2-ACETYL-1-PYRROLINE AND THE STABLE PRECURSOR THEREOF, OPTIONALLY ISOTOPICALLY MARKED
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, (2012/05/04)
The present invention relates to a method for synthetizing a compound of the following formula (I): wherein R is a methyl or ethyl group, n is 1 or 2, and X is a CH2 or CD2 group, from a compound of the following formula (II): wherein R and n are as defined above, and also relates to a method for assaying the compounds of the formula (I) using a corresponding deuterated derivative as an internal reference, as well as to the use of ketal derivatives of compounds of the formula (I) as a stable precursor, in particular in a flavoring composition.
A general method for the synthesis of the most powerful naturally?occurring Maillard flavors
Fuganti, Claudio,Gatti, Francesco G.,Serra, Stefano
, p. 4762 - 4767 (2007/10/03)
The natural flavors 2-acetyl-1-pyrroline 1a, 2-propionyl-1-pyrroline 1b, 2-acetyl-3,4,5,6-tetrahydropyridine 1c, 2-acetyl-2-thiazoline 1d, 2-propionyl-2-thiazoline 1e, and the artificial flavor 2-acetyl-5,6-dihydro-4H-1,3-thiazine 1f have been prepared by catalytic SeO2 oxidation of the corresponding cyclic imines 6a-c and sulfur cyclic imines 7a-c using TBHP as co-oxidant. The oxidation of the pyrrolines 1a and b is completely regioselective. Professional olfactory evaluation together with the odor threshold of the new flavor 1f is reported.
An efficient one-pot synthesis of pyrrolines and tetrahydropyridines from their chloro-precursors via in situ aza-Wittig reaction
Singh, Pradeep N.D.,Klima, Rodney F.,Muthukrishnan, Sivaramakrishnan,Murthy, Rajesh S.,Sankaranarayanan, Jagadis,Stahlecker, Heidi M.,Patel, Bhavika,Gudmundsdóttir, Anna D.
, p. 4213 - 4217 (2007/10/03)
A simple and efficient method for synthesizing pyrrolines and tetrahydropyridines via an intramolecular aza-Wittig reaction has been achieved by microwave irradiation of the corresponding chloro-alkane derivatives in the presence of tertiary phosphite and sodium azide. The in situ formation of the alkyl azides makes this a facile and safe method for aza-Wittig reactions.
2-Oxopropanal, Hydroxy-2-propanone, and 1-Pyrroline - Important Intermediates in the Generation of the Roast-Smelling Food Flavor Compounds 2-Acetyl-1-pyrroline and 2-Acetyltetrahydropyridine
Hofmann, Thomas,Schieberle, Peter
, p. 2270 - 2277 (2007/10/03)
On the basis of labeling experiments with [13C]6-glucose/unlabeled proline as well as quantitative data obtained in model studies using stable isotope dilution assays, 1-pyrroline and hydroxy-2-propanone were identified as effective intermediates in generating the roast-smelling food odorant 2-acetyltetrahydropyridine (ATHP; two tautomers). Synthesis of the key precursor compound, 2-(1-hydroxy-2-oxo-propyl)pyrrolidine, and studies on its degradation confirmed the important role of this intermediate in ATHP formation. Boiling of the intermediate for 30 min in aqueous solution generated >30% of ATHP on a molar basis. 1-Pyrroline and 2-oxopropanal were confirmed as important intermediates in the generation of the further roast food odorant, 2-acetyl-1-pyrroline (AP). On the basis of results of labeling experiments with [13C]6-glucose/unlabeled proline, two different mechanisms could be proposed. One leads to AP via 2-(1,2-dioxopropyl)pyrrolidine as the precursor with elimination of the aldehyde group in 2-oxopropanal as carbon dioxide. The other one suggests elimination of carbon-2 of the pyrroline ring. The latter mechanism was further established by a result showing that from the reaction of 2-methyl- 1-pyrroline with 2-oxopropanal AP was also generated.
Flavor Contribution and Formation of the Intense Roast-Smelling Odorants 2-Propionyl-1-pyrroline and 2-Propionyltetrahydropyridine in Maillard-Type Reactions
Hofmann, Thomas,Schieberle, Peter
, p. 2721 - 2726 (2007/10/03)
Application of aroma extract dilution analysis on two different model mixtures of proline and glucose, reacted under aqueous or dry-heating conditions, revealed 2-propionyl-1-pyrroline (PP) and 2-propionyltetrahydropyridine (PTHP; occurring in two tautomers), besides 2-acetyl-1-pyrroline and 2-acetyltetrahydropyridine, as important roast-smelling odorants in both mixtures. A comparison of the isotope distribution in PP and PTHP formed from either 13C6-labeled or unlabeled glucose suggested a formation pathway for both odorants from the same intermediate, 1-pyrroline, when reacted with either 2-oxobutanal (yielding PP) or 1-hydroxy-2-butanone (yielding PTHP). 2-Oxobutanal, a possible precursor of 1-hydroxy-2-butanone, was shown to be formed in high yields (29 mol %) by reacting acetaldehyde and glycolaldehyde, two well-known degradation products of carbohydrates.
Novel syntheses of the major flavor components of bread and cooked rice
De Kimpe, Norbert,Keppens, Marian
, p. 1515 - 1519 (2007/10/03)
A new synthetic pathway toward the Maillard flavor compounds 6-acyl-1,2,3,4-tetrahydropyridines and 2-acetyl-1-pyrroline is presented. The reaction sequence involves deprotonation of a vicinal diimine and subsequent alkylation with an N,N-diprotected ω-bromoalkylamine, followed by deprotection and intramolecular transimination of the functionalized intermediate. Acidic workup affords the above-mentioned heterocycles, which are principal flavor constituents of bread and cooked rice, respectively. In addition, the synthesis of the more stable diethyl acetal of 2-acetyl-1-pyrroline is described.
