151
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Synthesis and odor description of optically active cyclopropanated analogues of geraniol, nerol, nor-leaf alcohol, and matsutake alcohol. ACTA ACUST UNITED AC 2007. [DOI: 10.1016/j.tetasy.2007.02.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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152
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Abstract
In 1896, Tiemann first raised the question of whether or not enantiomers might exhibit different odors. The classic work of von Braun should have settled the issue in 1927 but the debate continued for decades, often rather acrimoniously. Various factors such as purity of samples and subjectivity of odors provided the confusion necessary to perpetuate disagreement. Nowadays, we have enough good-quality data to know that sometimes, absolute configuration affects odor perception and sometimes it does not. We are, therefore, left with some interesting academic and commercial questions to be addressed.
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153
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Brookes JC, Hartoutsiou F, Horsfield AP, Stoneham AM. Could humans recognize odor by phonon assisted tunneling? PHYSICAL REVIEW LETTERS 2007; 98:038101. [PMID: 17358733 DOI: 10.1103/physrevlett.98.038101] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2006] [Indexed: 05/14/2023]
Abstract
Our sense of smell relies on sensitive, selective atomic-scale processes that occur when a scent molecule meets specific receptors in the nose. The physical mechanisms of detection are unclear: odorant shape and size are important, but experiment shows them insufficient. One novel proposal suggests receptors are actuated by inelastic electron tunneling from a donor to an acceptor mediated by the odorant, and provides critical discrimination. We test the physical viability of this mechanism using a simple but general model. With parameter values appropriate for biomolecular systems, we find the proposal consistent both with the underlying physics and with observed features of smell. This mechanism suggests a distinct paradigm for selective molecular interactions at receptors (the swipe card model): recognition and actuation involve size and shape, but also exploit other processes.
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Affiliation(s)
- Jennifer C Brookes
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom.
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154
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Shimotori Y, Nakahachi Y, Inoue K, Miyakoshi T. Synthesis of optically activeγ-lactones via lipase-catalyzed resolution. FLAVOUR FRAG J 2007. [DOI: 10.1002/ffj.1816] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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155
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Serra S, Fuganti C, Brenna E. Two easy photochemical methods for the conversion of commercial ionone alpha into regioisomerically enrichedγ-ionone andγ-dihydroionone. FLAVOUR FRAG J 2007. [DOI: 10.1002/ffj.1832] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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156
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157
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Hao X, Hoshi N. Facile and Recyclable Method for the Prins Reaction Using Hafnium(IV) Bis(perfluorooctanesulfonyl)amides in Fluorous Biphase System. CHEM LETT 2006. [DOI: 10.1246/cl.2006.1102] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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158
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159
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Scafato P, Larocca A, Rosini C. An alternative stereoselective synthesis of the macrocyclic fragrances (R)-12-methyltridecanolide and (S)-muscolide by means of an asymmetric catalytic conjugate addition/Baeyer–Villiger oxidation. ACTA ACUST UNITED AC 2006. [DOI: 10.1016/j.tetasy.2006.09.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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160
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Volatile composition of oak and chestnut woods used in brandy ageing: Modification induced by heat treatment. J FOOD ENG 2006. [DOI: 10.1016/j.jfoodeng.2005.05.008] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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161
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Ramón DJ, Yus M. Asymmetric multicomponent reactions (AMCRs): the new frontier. Angew Chem Int Ed Engl 2006; 44:1602-34. [PMID: 15719349 DOI: 10.1002/anie.200460548] [Citation(s) in RCA: 1405] [Impact Index Per Article: 78.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Asymmetric multicomponent reactions involve the preparation of chiral compounds by the reaction of three or more reagents added simultaneously. This kind of addition and reaction has some advantages over classic divergent reaction strategies, such as lower costs, time, and energy, as well as environmentally friendlier aspects. All these advantages, together with the high level of stereoselectivity attained in some of these reactions, will force chemists in industry as in academia to adopt this new strategy of synthesis, or at least to consider it as a viable option. The positive aspects as well as the drawbacks of this strategy are discussed in this Review.
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Affiliation(s)
- Diego J Ramón
- Instituto de Síntesis Orgánica y Departamento de Química Orgánica, Facultad de Ciencias, Universidad de Alicante, Apdo. 99, 03080-Alicante, Spain
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162
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Serra S, Fuganti C. Synthesis of the enantiomeric forms of α- and γ-damascone starting from commercial racemic α-ionone. ACTA ACUST UNITED AC 2006. [DOI: 10.1016/j.tetasy.2006.05.024] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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163
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Serra S, Fuganti C, Brenna E. Synthesis, Olfactory Evaluation, and Determination of the Absolute Configuration of the 3,4-Didehydroionone Stereoisomers. Helv Chim Acta 2006. [DOI: 10.1002/hlca.200690109] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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164
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Conversion of γ-substituted bicyclo[2.2.1] (Z)-vinylsulfones to the corresponding (E)-allylsulfones. Tetrahedron Lett 2006. [DOI: 10.1016/j.tetlet.2006.01.099] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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165
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Ulland S, Ian E, Borg-Karlson AK, Mustaparta H. Discrimination between enantiomers of linalool by olfactory receptor neurons in the cabbage moth Mamestra brassicae (L.). Chem Senses 2006; 31:325-34. [PMID: 16495438 DOI: 10.1093/chemse/bjj036] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Plants emit complex blends of volatiles, including chiral compounds that might be detected by vertebrates and invertebrates. Insects are ideal model organisms for studying the underlying receptor neuron mechanisms involved in olfactory discrimination of enantiomers. In the present study, we have employed two-column gas chromatography linked to recordings from single olfactory receptor neurons of Mamestra brassicae, in which separation of volatiles in a polar and a chiral column was performed. We here present the response properties of olfactory receptor neurons tuned to linalool. The narrow tuning of these receptor neurons was demonstrated by their strong responses to (R)-(-)-linalool, the weaker responses to the (+)-enantiomer as well as a few structurally related compounds, and no responses to the other numerous plant released volatiles. The enantioselectivity was verified by parallel dose-response curves, that of (R)-(-)-linalool shifted 1 log unit to the left of the (S)-(+)-linalool curve. A complete overlap of the temporal response pattern was found when comparing the responses of the same strength. Analysis of the spike amplitude and waveform indicated that the responses to the two enantiomers originated from the same neuron.
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Affiliation(s)
- Stig Ulland
- Neuroscience Unit, Department of Biology, Norwegian University of Science and Technology, NO-7489 Trondheim, Norway.
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166
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Abate A, Allievi M, Brenna E, Fuganti C, Gatti F, Serra S. Enzymatic Approach to and Odor Description of the Twelve Enantiomerically Pure Isomers ofPelargene®. Helv Chim Acta 2006. [DOI: 10.1002/hlca.200690020] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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167
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Begnaud F, Starkenmann C, Van de Waal M, Chaintreau A. Chiral Multidimensional Gas Chromatography (MDGC) and Chiral GC–Olfactometry with a Double-Cool-Strand Interface: Application to Malodors. Chem Biodivers 2006; 3:150-60. [PMID: 17193253 DOI: 10.1002/cbdv.200690018] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Volatile sulfur compounds such as 3-methyl-3-sulfanylhexan-1-ol (1) are largely responsible for axillary-sweat malodors. In this work, we describe the determination of the enantiomer ratio of the trace constituent 1 and the odor description of its antipodes (R)- and (S)-1 by means of multidimensional gas chromatography (MDGC) in combination with chiral gas chromatography-olfactometry (GC-O). This technique allowed the on-line evaluation of the sensory character of both enantiomers via a sniffing port, and is based on a novel double-cool-strand interface (DCSI). First, the system's inertness was tested towards the labile compound 2-methylfuran-3-thiol (MFT; 2). Then, the DCSI was used in a new configuration to achieve olfactive characterization by means of chiral GC-O. In contrast to direct smelling after the chiral column, our technique allows, for the first time, to significantly delay the perception of the second-eluting enantiomer after the first one. This lowers the risk of sensory saturation, as the panelist can recover from the first stimulus, before evaluating the second one. To help programming the DCSI, a dedicated program was set up. The enantiomer ratio of the sweat malodor 1 was determined as (S)/(R) 3 : 1, and the dominating (S)-isomer was shown to largely impart its specific character to the overall odor of the sweat extract.
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Affiliation(s)
- Frédéric Begnaud
- Firmenich SA, Corporate R&D Division, CH-1211 Geneva 8, Switzerland
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168
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Headspace Hanging Drop Liquid Phase Microextraction and GC-MS for the Determination of Linalool from Evening Primrose Flowers. B KOREAN CHEM SOC 2005. [DOI: 10.5012/bkcs.2005.26.12.1996] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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169
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Castro JM, Linares-Palomino PJ, Salido S, Altarejos J, Nogueras M, Sánchez A. Enantiospecific synthesis, separation and olfactory evaluation of all diastereomers of a homologue of the sandalwood odorant Polysantol®. Tetrahedron 2005. [DOI: 10.1016/j.tet.2005.09.023] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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170
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de Carvalho CCCR, da Fonseca MMR. Biotransformation of terpenes. Biotechnol Adv 2005; 24:134-42. [PMID: 16169182 DOI: 10.1016/j.biotechadv.2005.08.004] [Citation(s) in RCA: 160] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2005] [Accepted: 08/13/2005] [Indexed: 10/25/2022]
Abstract
The main application of terpenes as fragrances and flavors depends on the absolute configuration of the compounds because enantiomers present different organoleptic properties. Biotransformations allow the production of regio- and stereoselective compounds under mild conditions. These products may be labeled as "natural". Commercially useful chemical building-blocks and pharmaceutical stereo isomers can also be produced by bioconversion of terpenes. Enzymes and extracts from bacteria, cyanobacteria, yeasts, microalgae, fungi, plants, and animal cells have been used for the production and/or bioconversion of terpenes. In addition, whole cell catalysis has also been used. A variety of media and reactors have been assessed for these biotransformations and have produced encouraging results, as discussed in this review.
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Affiliation(s)
- Carla C C R de Carvalho
- Centro de Engenharia Biológica e Química, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa, Lisbon, Portugal.
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171
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Abstract
During the past years biocatalytic production of fine chemicals has been expanding rapidly. Flavours and fragrances belong to many different structural classes and therefore represent a challenging target for academic and industrial research. Here, we present a condensed overview of the potential offered by biocatalysis for the synthesis of natural and natural-identical odorants, highlighting relevant biotransformations using microorganisms and isolated enzymes. The industrial processes based on biocatalytic methods are discussed in terms of their advantages over classical chemical synthesis and extraction from natural sources. Recent applications of the biocatalytic approach to the preparation of the most important fine odorants are comprehensively covered.
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Affiliation(s)
- Stefano Serra
- C.N.R. Consiglio Nazionale delle Richerche, Istituto di Chimica del Riconoscimento Molecolare, Sezione A. Quilico' (Institute of Chemistry of Molecular Recognition, A. Quilico section), Via Mancinelli 7, I-20133 Milano, Italy.
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172
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Lactones 23: Synthesis of cis-fused bicyclic hydroxy lactones with a p-menthane system. ACTA ACUST UNITED AC 2005. [DOI: 10.1016/j.tetasy.2005.04.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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173
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Brenna E, Fuganti C, Serra S. Synthesis and olfactory evaluation of the enantiomerically enriched forms of 7,11-epoxymegastigma-5(6)-en-9-one and 7,11-epoxymegastigma-5(6)-en-9-ols isomers, identified in Passiflora edulis. ACTA ACUST UNITED AC 2005. [DOI: 10.1016/j.tetasy.2005.02.021] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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174
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175
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Ramón DJ, Yus M. Neue Entwicklungen in der asymmetrischen Mehrkomponenten-Reaktion. Angew Chem Int Ed Engl 2005. [DOI: 10.1002/ange.200460548] [Citation(s) in RCA: 352] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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176
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Abate A, Brenna E, Fuganti C, Gatti FG, Giovenzana T, Malpezzi L, Serra S. Chirality and Fragrance Chemistry: Stereoisomers of the Commercial Chiral Odorants Muguesia and Pamplefleur. J Org Chem 2005; 70:1281-90. [PMID: 15704962 DOI: 10.1021/jo048445j] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
[structure: see text] The work describes the enzyme-mediated preparation and the odor evaluation of the single stereoisomers of the commercial odorants Muguesia and Pamplefleur. The synthetic approach to Muguesia stereoisomers helped to clear the assignment of the relative configuration of intermediate diols 5. The odor response of Pamplefleur isomers was found to be rather unusual. No stereoisomer prevailed, but each one played a definite role in establishing the odor sensation of the final blend.
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Affiliation(s)
- Agnese Abate
- Dipartimento di Chimica, Materiali ed Ingegneria Chimica del Politecnico, Istituto CNR per la Chimica del Riconoscimento Molecolare, Via Mancinelli 7, I-20131 Milano, Italy
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177
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Larkov O, Dunkelblum E, Zada A, Lewinsohn E, Freiman L, Dudai N, Ravid U. Enantiomeric composition of (E)- and (Z)-sabinene hydrate and their acetates in ?veOriganum spp. FLAVOUR FRAG J 2005. [DOI: 10.1002/ffj.1386] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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178
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Abate A, Brenna E, Fuganti C, Gatti FG, Serra S. Odor and (Bio)diversity: Single Enantiomers of Chiral Fragrant Substances. Chem Biodivers 2004; 1:1888-98. [PMID: 17191827 DOI: 10.1002/cbdv.200490145] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Our sense of smell is enantioselective. This review reports interesting examples of single stereoisomers of natural and synthetic odorants, prepared via bioorganic routes, that support this statement. This article is the summary of a talk given at the Flavours & Fragrances 2004 conference in Manchester at the MCC/UMIST, 12-14 May, 2004.
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Affiliation(s)
- Agnese Abate
- Dipartimento di Chimica, Materiali ed Ingegneria Chimica del Politecnico, Istituto CNR per la Chimica del Riconoscimento Molecolare, Via Mancinelli 7, I-20131 Milano
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179
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Fráter G, Müller U, Schröder F. Synthesis and olfactory properties of (−)-(1R,2S)-Georgywood. ACTA ACUST UNITED AC 2004. [DOI: 10.1016/j.tetasy.2004.11.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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180
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Kim NS, Lee DS. Headspace solid-phase microextraction for characterization of fragrances of lemon verbena (Aloysia triphylla) by gas chromatography-mass spectrometry. J Sep Sci 2004; 27:96-100. [PMID: 15335064 DOI: 10.1002/jssc.200301603] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Natural fragrances from lemon verbena (Aloysia triphylla) were studied by headspace solid phase microextraction (HS-SPME) techniques followed by gas chromatography-mass spectrometry (GC-MS), with six different fibre coatings being tested to evaluate the extraction efficiencies of several selected compounds. A total of 14 compounds were identified in the fragrances of lemon verbena. Geranial and neral were detected as major components and alpha-pinene, beta-pinene, beta-caryophyllene, and curcumene as minor components. Enantiomeric analysis of chiral compounds from lemon verbena was carried out on a chiral column. alpha-Pinene, limonene, and camphor in the fragrances emitted from lemon verbena were found in the (+), (-), and (-) forms, respectively.
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Affiliation(s)
- Nam-Sun Kim
- Department of Chemistry, Seoul Women's University, Seoul 139-774, South Korea
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181
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Margot C, Simmons D, Reichlin D, Skuy D. Amber-Woody Scent: Alcohols with Divergent Structure Present Common Olfactory Characteristics and Sharp Enantiomer Differentiation. Helv Chim Acta 2004. [DOI: 10.1002/hlca.200490237] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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182
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Pollini GP, Bianchi A, Casolari A, De Risi C, Zanirato V, Bertolasi V. An efficient approach to chiral nonracemic trans- and cis-decalin scaffolds for drimane and labdane synthesis. ACTA ACUST UNITED AC 2004. [DOI: 10.1016/j.tetasy.2004.07.064] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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183
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Scafato P, Cunsolo G, Labano S, Rosini C. Asymmetric activation of tropos catalysts in the stereoselective catalytic conjugate additions of R2Zn to α,β-enones: an efficient synthesis of (−)-muscone. Tetrahedron 2004. [DOI: 10.1016/j.tet.2004.07.034] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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184
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Deoxycholic acid-based phosphites as chiral ligands in the enantioselective conjugate addition of dialkylzincs to cyclic enones: preparation of (−)-(R)-muscone. ACTA ACUST UNITED AC 2004. [DOI: 10.1016/j.tetasy.2004.07.009] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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185
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Benincori T, Rizzo S, Pilati T, Ponti A, Sada M, Pagliarini E, Ratti S, Giuseppe C, de Ferra L, Sannicolò F. Process-scale preparation of enantiomerically pure γ-lactones by asymmetric hydrogenation of γ-ketoesters and comparative tests of the sensory properties of some antipodes. ACTA ACUST UNITED AC 2004. [DOI: 10.1016/j.tetasy.2004.06.024] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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186
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Enders D, Backes M. First asymmetric synthesis of both enantiomers of Tropional® and their olfactory evaluation. ACTA ACUST UNITED AC 2004. [DOI: 10.1016/j.tetasy.2004.04.026] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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187
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188
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Serra S, Brenna E, Fuganti C, Maggioni F. Lipase-catalyzed resolution of p-menthan-3-ols monoterpenes: preparation of the enantiomer-enriched forms of menthol, isopulegol, trans- and cis-piperitol, and cis-isopiperitenol. ACTA ACUST UNITED AC 2003. [DOI: 10.1016/j.tetasy.2003.08.010] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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189
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Enantioselective synthesis of benzylic stereocentres via Claisen rearrangement of enantiomerically pure allylic alcohols: preparation of (R)- and (S)-3-methyl-2-phenylbutylamine. ACTA ACUST UNITED AC 2003. [DOI: 10.1016/s0957-4166(03)00454-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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190
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Boto A, Hernández D, Hernández R, Suárez E. beta-Fragmentation of primary alkoxyl radicals versus hydrogen abstraction: synthesis of polyols and alpha,omega-differently substituted cyclic ethers from carbohydrates. J Org Chem 2003; 68:5310-9. [PMID: 12816493 DOI: 10.1021/jo034442f] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The beta-fragmentation of primary alkoxyl radicals, described in many cases as low-yielding and plagued by side reactions, can proceed in satisfactory yields using carbohydrate substrates. The only reaction that can compete significantly with the beta-scission is the intramolecular hydrogen abstraction. The ratio of beta-fragmentation to hydrogen abstraction can be varied according to the reaction conditions, the stereochemistry of the substituents (e.g., alpha- or beta-anomeric substituents), and the protecting groups chosen. The carbohydrate substrates are easily prepared, and the mild reaction conditions are compatible with most functional groups. The beta-scission reaction provides an expedient way toward shorter and less common sugar series and also toward alpha,omega-differently substituted cyclic ethers. These units are useful building blocks and are present in many natural products with interesting biological activity.
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Affiliation(s)
- Alicia Boto
- Instituto de Productos Naturales y Agrobiología del C.S.I.C., Carretera de La Esperanza 3, 38206 La Laguna, Tenerife, Spain
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191
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