18374-76-0Relevant articles and documents
GUAIANE SESQUITERPENES FROM AGARWOOD
Ishihara, Masakazu,Tsuneya, Tomoyuki,Uneyama, Kenji
, p. 3343 - 3347 (1991)
Key Word Index - Aquilaria agallocha; Thymelaeaceae; agarwood; sesquiterpenes; (-)-guaia-1(10),11-dien-15-ol; (-)-guaia-1(10),11-diene-15-carboxylic acid; methyl guaia-1(10),11-diene-15-carboxylate; (+)-guaia-1(10),11-dien-9-one; (-)-1,10-epoxyguai-11-ene; (-)-guaia-1(10),11-dien-15,2-olide; (-)-rotundone.Seven new sesquiterpenes, all of which have a guaiane skeleton, i.e. (-)-guaia-1(10),11-dien-15-ol, (-)-guaia-1(10),11-diene-15-carboxylic acid, methyl guaia-1(10),11-diene-15-carboxylate, (+)-guaia-1(10),11-dien-9-one, (-)-1,10-epoxyguai-11-ene, (-)-guaia-1(10),11-dien-15,2-olide and (-)-rotundone, have been isolated from Aquilaria agallocha (agarwood).Their structures have been established on the bases of detailed spectroscopic analyses and synthesis.
Effective analysis of rotundone at below-threshold levels in red and white wines using solid-phase microextraction gas chromatography/tandem mass spectrometry
Mattivi,Caputi,Carlin,Lanza,Minozzi,Nanni,Valenti,Vrhovsek
, p. 483 - 488 (2011)
Rotundone is an oxygenated sesquiterpene belonging to the family of guaianes, giving the 'peppery' aroma to white and black pepper and to red wines. Here we describe a novel, convenient protocol for the synthesis of rotundone, starting from a commercially available compound and requiring only two reaction steps, and an improved, faster method of GC separation (30min) with selective quantisation of rotundone using tandem mass spectrometry in multiple reaction monitoring (MRM) mode with d5-rotundone as internal standard. With limits of detection (LODs) of 1.5ng/L in white wine and 2.0ng/L in red wine, intraday repeatability CV values of 6% and 5% at 50ng/L and 500ng/L and interday repeatability CV values of 13% and 6% at 50ng/L and 500ng/L, respectively, the improved protocol provides the desired sensitivity and selectivity for routine analysis of rotundone in both white and red wines. Initial application of this method highlighted the presence of unexpectedly high concentrations of rotundone, thus explaining the origin of the distinctive peppery aroma in Schioppettino and Vespolina red wines and in Gruener Veltliner white wines.
Development of a synthesis method for odor sesquiterpenoid, (?)-rotundone, using non-heme Fe2+-chelate catalyst and ferric-chelate reductase
Umezawa, Satoru,Konishi, Shunsuke,Kino, Kuniki
, p. 1875 - 1883 (2019)
(?)-Rotundone, a sesquiterpenoid that has a characteristic woody and peppery odor, is a key aroma component of spicy foodstuffs, such as black pepper and Australian Shiraz wine. (?)-Rotundone shows the lowest level of odor threshold in natural compounds and remarkably improves the quality of various fruit flavors. To develop a method for the synthesis of (?)-rotundone, we focused on non-heme Fe2+-chelates, which are biomimetic catalysts of the active center of oxygenases and enzymatic supply and regeneration of those catalysts. That is, we constructed a unique combination system composed of the oxidative synthesis of (?)-rotundone using the non-heme Fe2+-chelate catalyst, Fe(II)-EDTA, and the enzymatic supply and regeneration of Fe2+-chelate by ferric-chelate reductase, YqjH, from Escherichia coli. In addition, we improved the yield of (?)- rotundone by the application of cyclodextrin and glucose dehydrogenase to this system, and thus established a platform for efficient (?)-rotundone production.
Total Synthesis of (?)-Rotundone and (?)-epi-Rotundone from Monoterpene Precursors
Rüthi, Fabian,Schr?der, Fridtjof
, (2020/10/30)
The first total synthesis of (?)-rotundone has been accomplished from (+)-(R)-limonene and therefore for the first time from an unrelated monoterpene instead of modifying structurally closely related sesquiterpene precursors such as α-guaiene. Challenges such as intermediates with stereocenters prone to epimerization by enolization were overcome by designing a β-methyl-keto route starting from (+)-(R)-limonene which finally gave (?)-rotundone by Nazarov cyclization of a precursor 13a. Diastereomer (?)-epi-rotundone was separated from (?)-rotundone chromatographically. An alternative route from rac-citronellal provided a diastereomer mixture of racemic Nazarov precursor 13 through a TRIP-catalyzed intramolecular aldolization, thus indicating that the Nazarov cyclization precursor 13a is in principle accessible from (?)-(S)-citronellal. The 11-step synthesis from (+)-(R)-limonene with ca. 1 % overall yield confirmed the absolute configuration of (?)-rotundone and provided samples of good olfactory quality.
PRODUCTION OF GUAIENE AND ROTUNDONE
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Page/Page column 19; 20, (2019/06/23)
Proposed is a process for producing rotundone from α-guaiene, in particular by oxidation of the C(3) position, wherein the α-guaiene is produced from a precursor by a sesquiterpene synthase. The sesquiterpene synthase is produced in a microorganism.
IMPROVEMENTS IN OR RELATING TO ORGANIC COMPOUNDS
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Page/Page column 8; 9; 10, (2019/06/23)
An allylic oxidation process comprising: forming a mixture containing α-Guaiene and an iron (III)-X porphyrin complex catalyst in a sustainable solvent, introducing molecular oxygen into the mixture, and effecting allylic oxidation to produce an α,?-unsaturated ketone, Rotundone.
Identification of Rotundone as a Potent Odor-Active Compound of Several Kinds of Fruits
Nakanishi, Akira,Fukushima, Yusuke,Miyazawa, Norio,Yoshikawa, Keisuke,Maeda, Tomoko,Kurobayashi, Yoshiko
, p. 4464 - 4471 (2017/06/13)
An investigation of the aromas of grapefruit, orange, apple, and mango revealed the presence of an odor-active compound that gave off a strong woody odor when assessed by gas chromatography-olfactometry. We isolated the compound from a high-boiling fraction of an orange essential oil, and subsequent nuclear magnetic resonance analyses of the isolated compound identified it as rotundone. Mass spectra and retention indices obtained from aroma concentrates of grapefruit, apple, and mango were identical to those of rotundone, which was therefore determined to be the common woody compound in these fruits. Sensory analyses were performed to assess the effects of rotundone on model beverages of the various fruits. It was revealed that rotundone added at even subthreshold levels to model beverages did not confer directly the woody odor, but had significant effects on the overall flavors of the beverages, helping them to better approximate the natural flavors of the fruits.
Scalable and sustainable electrochemical allylic C-H oxidation
Horn, Evan J.,Rosen, Brandon R.,Chen, Yong,Tang, Jiaze,Chen, Ke,Eastgate, Martin D.,Baran, Phil S.
, p. 77 - 81 (2016/06/01)
New methods and strategies for the direct functionalization of C-H bonds are beginning to reshape the field of retrosynthetic analysis, affecting the synthesis of natural products, medicines and materials. The oxidation of allylic systems has played a prominent role in this context as possibly the most widely applied C-H functionalization, owing to the utility of enones and allylic alcohols as versatile intermediates, and their prevalence in natural and unnatural materials. Allylic oxidations have featured in hundreds of syntheses, including some natural product syntheses regarded as € classics €. Despite many attempts to improve the efficiency and practicality of this transformation, the majority of conditions still use highly toxic reagents (based around toxic elements such as chromium or selenium) or expensive catalysts (such as palladium or rhodium). These requirements are problematic in industrial settings; currently, no scalable and sustainable solution to allylic oxidation exists. This oxidation strategy is therefore rarely used for large-scale synthetic applications, limiting the adoption of this retrosynthetic strategy by industrial scientists. Here we describe an electrochemical C-H oxidation strategy that exhibits broad substrate scope, operational simplicity and high chemoselectivity. It uses inexpensive and readily available materials, and represents a scalable allylic C-H oxidation (demonstrated on 100 grams), enabling the adoption of this C-H oxidation strategy in large-scale industrial settings without substantial environmental impact.
Mechanistic studies on the autoxidation of α-guaiene: Structural diversity of the sesquiterpenoid downstream products
Huang, An-Cheng,Sefton, Mark A.,Sumby, Christopher J.,Tiekink, Edward R. T.,Taylor, Dennis K.
, p. 131 - 145 (2015/02/05)
Two unstable hydroperoxides, 6b and 10a, and 13 downstream sesquiterpenoids have been isolated from the autoxidation mixture of the bicyclic sesquiterpene α-guaiene (1) on cellulose filter paper. One of the significant natural products isolated was rotundone (2), which is the only known impact odorant displaying a peppery aroma. Other products included corymbolone (4a) and its C-6 epimer 4b, the (2R)- and (2S)-rotundols (7a/b), and several hitherto unknown epimers of natural chabrolidione A, namely, 7-epi-chabrolidione A (3a) and 1,7-epi-chabrolidione A (3b). Two 4-hydroxyrotundones (8a/b) and a range of epoxides (9a/b and 5a/b) were also formed in significant amounts after autoxidation. Their structures were elucidated on the basis of spectroscopic data and X-ray crystallography, and a number of them were confirmed through total synthesis. The mechanisms of formation of the majority of the products may be accounted for by initial formation of the 2- and 4-hydroperoxyguaienes (6a/b and 10a/b) followed by various fragmentation or degradation pathways. Given that α-guaiene (1) is well known to exist in the essential oils of numerous plants, coupled with the fact that aerial oxidation to form this myriad of downstream oxidation products occurs readily at ambient temperature, suggests that many of them have been overlooked during previous isolation studies from natural sources.
1-HYDROXY-OCTAHYDROAZULENES AS FRAGRANCES
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Page/Page column 15-16, (2012/01/14)
(3S,5R)-3,8-dimethyl-5-(prop-1-en-2-yl)-octahydroazulen-1-ols, their use as flavour or fragrance ingredient, and a process of their production by oxidation in the presence of laccase.
