616-16-0Relevant academic research and scientific papers
Influence of the Production Process on the Key Aroma Compounds of Rum: From Molasses to the Spirit
Franitza, Laura,Granvogl, Michael,Schieberle, Peter
, p. 9041 - 9053 (2016)
The production of rum consists of fermentation, distillation, and aging. To check the influence of each step on the final rum aroma, molasses, mash, distillate, and the final rum were analyzed using the sensomics concept. The changes in key aroma compounds were determined by application of aroma extract dilution analysis (AEDA) in combination with gas chromatography-mass spectrometry for identification and by stable isotope dilution assays (SIDAs) for quantitation. Odor activity values (OAVs; ratio of concentration to respective odor threshold) were calculated for the compounds determined in the rum and, finally, the rum aroma was successfully simulated by recombination. (E)-β-Damascenone showed by far the highest OAV (3280) in rum. Although this compound was determined already in molasses, its concentration increased significantly during distillation, indicating a thermolabile precursor. Vanillin, 4-ethylphenol, 2-methoxyphenol, 4-ethyl-2-methoxyphenol, and 2-methoxy-4-propylphenol are well-known compounds mainly stemming from the wood barrels used for aging and showed an OAV ≥ 1. Another important group of aroma-active compounds in rum were ethyl esters, for which a significant increase was determined during fermentation but also to a lesser extent during aging. Altogether, the concentrations of 68% of the aroma-active compounds increased during the process, demonstrating its influence on the overall rum aroma.
Decadienoates: Sex pheromone components of nettle caterpillars Darna trima and D. bradleyi
Sasaerila, Yorianta,Gries, Regine,Gries, Gerhard,Khaskin, Grigori,King, Skip,Chor Boo, Teo
, p. 1969 - 1981 (2000)
This study was undertaken to identify sex pheromone components of nettle caterpillars Darna trima and Darna bradleyi (Lepidoptera: Limacodidae) whose larvae defoliate oil palm, Elaeis guineensis, in southeast Asia. Coupled gas chromatographic-electroantennographic detection (GC-EAD) analyses of pheromone gland extracts revealed two antennally active compounds produced by female D. trima and two by female D. bradleyi. Molecular structures of these candidate pheromone components were identified by electron-impact and chemical-ionization mass spectrometry; retention-index calculations on DB-5, DB-23, and DB-210 columns; microanalytical treatments, as well as syntheses of 'auxilliary' compounds that facilitated identification of the compounds. The compounds from D. trima were 2-methylbutyl (E)-7,9-decadienoate (A) and (E)-2-hexenyl (E)-7,9-decadienoate (B); from D. bradleyi we identified methyl (E)-7,9-decadienoate (C), and isobutyl (E)-7,9-decadienoate (D). In field experiments in Malaysia, (S)-2-methylbutyl (E)-7,9-decadienoate (SA) in combination with B proved to be essential and synergistic pheromone components for attraction of male D. trima. (R)-2-Methylbutyl (E)-7,9-decadienoate (RA) had no behavioral activity. Compound D singly attracted male D. bradleyi, but addition of C to D at a 1:10 ratio significantly enhanced attractiveness of the bait. Synthetic pheromone blends were more effective trap baits than unmated female moths and could be developed for monitoring populations of D. trima and D. bradleyi in Asian oil palm plantations.
Structure-Elucidating Total Synthesis of the (Polyenoyl)tetramic Acid Militarinone C §
Brückner, Reinhard,Drescher, Christian,Hamburger, Matthias,Keller, Morris,Potterat, Olivier
supporting information, (2020/03/30)
The (polyenoyl)tetramic acid militarinone C (1) heads a family of seven members. Before our work, the configuration of C-5 was unknown whereas the configurations of C-8′ and C-10′ were either (R,R) or (S,S). We synthesized the four stereoisomers of constitution 1, which conform with these insights. This included cross-coupling both enantiomers of the western building block (8) with both enantiomers of the eastern building block (9). The specific rotations of the resulting 1 isomers suggested that natural 1 is configured like the coupling partners (S)-8 and (R,R)-9. This conclusion was corroborated by degrading natural 1 to alcohol 35 and by proving its configurational identity with synthetic (R,R)-35.
Asymmetric total synthesis of four stereoisomers of the sex pheromone of the western corn rootworm
Sun, Zhi-Feng,Zhang, Tao,Liu, Jinyang,Du, Zhen-Ting,Zheng, Huaiji
, (2018/03/30)
A convergent synthesis of four stereoisomers of the sex pheromone of the western corn rootworm (8-methyldecan-2-yl propionate, 1) from commercially available chiral starting materials is reported. The key step was Julia–Kocienski olefination between chiral BT-sulfone and chiral aldehyde. This synthetic route provided the four stereoisomers of 1 in 24–29% total yield via a six-step sequence. The simple scale-up strategy provides a new way to achieve the asymmetric synthesis of the sex pheromone.
Synthesis method and application of diabrotica virgifera virgifera le conte sex pheromone
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Paragraph 0073; 0092; 0105-0107, (2018/07/15)
The invention belongs to the technical field of pesticide chemistry, and discloses a synthesis method and application of diabrotica virgifera virgifera le conte sex pheromone. The synthesis method comprises the steps of enabling chiral sulfone compounds, i.e., (S)-2-methylbutyl thiazolsulfone and (R)-2-methylbutyl thiazolsulfone to be respectively subjected to a Julia-Kocienski coupling reaction with chiral aldehyde compounds, i.e., (S)-6-aldehyde hexan-2-ol propionate and (R)-6-aldehyde hexan-2-ol propionate, and carrying out hydrogenation reduction on the product of the coupling reaction soas to obtain the diabrotica virgifera virgifera le conte sex pheromone. In addition, the diabrotica virgifera virgifera le conte sex pheromone prepared by the method can be applied to the prevention and control of diabrotica virgifera virgifera le conte. The synthetic route of the diabrotica virgifera virgifera le conte sex pheromone is simplified, fewer by-products are produced in the reaction, and the reaction yield is greatly increased.
Strictly Alternating Sequences When Copolymerizing Racemic and Chiral Acetylene Monomers with an Organo-Rhodium Catalyst
Yoshida, Yoshiaki,Mawatari, Yasuteru,Sasaki, Takahiro,Hiraoki, Toshifumi,Wagner, Manfred,Müllen, Klaus,Tabata, Masayoshi
, p. 1291 - 1301 (2017/03/09)
A racemic mixture and two chiral monomers of 2-methyl-1-butyl propiolate, i.e., rac1, R1, and S1, were stereoregularly polymerized with a catalyst, [Rh(norbornadiene)Cl]2, in methanol at 40 °C to obtain the corresponding helical racemic and two chiral polymers, Prac1, PR1, and PS1, and a copolymer, Pco. The 1H and 13C NMR spectra of the racemic and chiral polymers differed, although the NMR spectra of their monomers were the same. The structures of the Pco copolymers with different chiral monomer ratios were analyzed using 1D and 2D NMR, optical rotation, circular dichroism (CD), UV-vis, and computational methods to elucidate the stereochemical effect of the chiral monomers together with the polymerization mechanism. The temperature dependence of 1H and 13C NMR spectra in line shape and intensity indicated that the helical main chain undergoes restricted rotation around the ester methylene bonds ?O-CH2- through a three-site jump exchange called an accordion-like helix oscillation (HELIOS). The energetically preferred structures of the helical-sense polymers PR1 or PS1 were simulated using the MMFF94 program. The dependence of the NMR spectral line shapes, optical rotations, and calculated structures on the monomer feed clearly indicated that the copolymers alternatively incorporate R1 and S1 to generate one-handed helical-sense chains. Based on these results, a polymerization mechanism is proposed, explaining a strictly alternating copolymerization that yields helical chains.
Polyunsaturated C-Glycosidic 4-Hydroxy-2-pyrone Derivatives: Total Synthesis Shows that Putative Orevactaene Is Likely Identical with Epipyrone A
Preindl, Johannes,Schulthoff, Saskia,Wirtz, Conny,Lingnau, Julia,Fürstner, Alois
supporting information, p. 7525 - 7530 (2017/06/13)
Orevactaene and epipyrone A were previously thought to comprise the same polyunsaturated tail but notably different C-glycosylated 4-hydroxy-2-pyrone head groups. Total synthesis now shows that the signature bicyclic framework assigned to orevactaene is a chimera; the compound is almost certainly identical with epipyrone A, whose previously unknown stereochemistry has also been established during this study. Key to success was the ready formation of the bicyclic core of putative orevactaene by a sequence of two alkyne cycloisomerization reactions using tungsten and gold catalysis. Equally important was the flexibility in the assembly process gained by the use of heterobimetallic polyunsaturated modules whose termini could be selectively and consecutively addressed in a practical one-pot cross-coupling sequence.
Rational Design of Thermodynamic and Kinetic Binding Profiles by Optimizing Surface Water Networks Coating Protein-Bound Ligands
Krimmer, Stefan G.,Cramer, Jonathan,Betz, Michael,Fridh, Veronica,Karlsson, Robert,Heine, Andreas,Klebe, Gerhard
, p. 10530 - 10548 (2016/12/16)
A previously studied congeneric series of thermolysin inhibitors addressing the solvent-accessible S2′ pocket with different hydrophobic substituents showed modulations of the surface water layers coating the protein-bound inhibitors. Increasing stabilization of water molecules resulted in an enthalpically more favorable binding signature, overall enhancing affinity. Based on this observation, we optimized the series by designing tailored P2′ substituents to improve and further stabilize the surface water network. MD simulations were applied to predict the putative water pattern around the bound ligands. Subsequently, the inhibitors were synthesized and characterized by high-resolution crystallography, microcalorimetry, and surface plasmon resonance. One of the designed inhibitors established the most pronounced water network of all inhibitors tested so far, composed of several fused water polygons, and showed 50-fold affinity enhancement with respect to the original methylated parent ligand. Notably, the inhibitor forming the most perfect water network also showed significantly prolonged residence time compared to the other tested inhibitors.
Domino Methylenation/Hydrogenation of Aldehydes and Ketones by Combining Matsubara's Reagent and Wilkinson's Catalyst
Maazaoui, Radhouan,Pin-Nó, María,Gervais, Kevin,Abderrahim, Raoudha,Ferreira, Franck,Perez-Luna, Alejandro,Chemla, Fabrice,Jackowski, Olivier
supporting information, p. 5732 - 5737 (2016/12/14)
The methylenation/hydrogenation cascade reaction of aldehydes or ketones through a domino process involving two ensuing steps in a single pot is realized. The compatibility of Matsubara's reagent and Wilkinson's complex give a combination that allows, under dihydrogen, the transformation of a carbonyl function into a methyl group. This new method is suitable to introduce an ethyl motif from aromatic and aliphatic aldehydes with total chemoselectivity and total retention of α-stereochemical purity. The developed procedure is also extended to the introduction of methyl groups from ketones.
PROCESSES FOR THE SYNTHESIS OF CHIRAL 1-ALKANOLS
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Paragraph 0212; 0213, (2016/12/01)
The invention relates to highly enantioselective processes for the synthesis of chiral 1-alkanols via Zr-catalyzed asymmetric carboalumination of alkenes.
