- Synthesis of Deuterium-Labeled 1,1,6-Trimethyl-1,2-dihydronaphthalene (TDN) and Quantitative Determination of TDN and Isomeric Vitispiranes in Riesling Wines by a Stable-Isotope-Dilution Assay
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The C13-norisoprenoid aroma compounds 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN) and isomeric 2,10,10-trimethyl-6-methylene-1-oxaspiro[4.5]dec-7-enes, so-called vitispiranes, are considered to be biosynthetically related. They occur at higher concentrations in bottle-aged Riesling wines especially and are important contributors to the varietal aroma of Riesling wines. Because of the variation of the quantitative methods and data reported in the literature, a redetermination of concentration levels for both free and total TDN and isomeric vitispiranes, especially in German Riesling wines, was performed using a stable-isotope-dilution assay (SIDA). For this purpose, a novel six-step synthetic route to TDN and deuterium-labeled TDN was developed. A standardized sample preparation for TDN and vitispiranes and a rapid acid-hydrolysis method at genuine wine-pH conditions for the conversion of the precursors into TDN and vitispiranes were also developed. Automated HS-SPME was applied to 250 wine samples from two wine competitions, and analysis was performed by gas chromatography-mass spectrometry with selected-ion monitoring (GC-SIM-MS) as well as selected-reaction monitoring (GC-SRM-MS).
- G?k, Recep,Bechtloff, Pia,Ziegler, Michael,Schmarr, Hans-Georg,Fischer, Ulrich,Winterhalter, Peter
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p. 6414 - 6422
(2019/06/07)
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- Iron-Catalyzed Synthesis of Dihydronaphthalenones from Aromatic Oxime Esters
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Herein, a convenient procedure on iron-catalyzed radical-mediated synthesis of dihydronaphthalenones from oxime esters has been developed. By using iron salt as a green and inexpensive catalyst, various α-aryl oxime esters were transformed into the corresponding dihydronaphthalenones in moderate to good yields with high chemo-selectivities. The reaction proceeds via 1,5-hydrogen atom transfer and then intramolecular radical cyclization sequence. (Figure presented.).
- Zhang, Youcan,Yin, Zhiping,Wu, Xiao-Feng
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supporting information
p. 3223 - 3227
(2019/05/10)
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- Design and synthesis of phosphotyrosine mimetics
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Selective inhibitors of protein tyrosine phosphatases (PTPases) are of great interest as therapeutic agents and research tools. Several phenylalanine derivatives (1, 2) designed as phosphotyrosine mimetics or irreversible active site inhibitors were successfully synthesized, then incorporated into a combinatorial library based on a peptidomimetic β-strand template.
- Yan, Zheng,Kahn, Michael,Qabar, Maher,Urban, Jan,Kim, Hwa-Ok,Blaskovich, Mark A.
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p. 2083 - 2085
(2007/10/03)
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