Odorant Design Based on the Carbon/Silicon Switch Strategy

Tacke, Reinhold; Metz, Stefan

doi:10.1002/cbdv.200890105

Cited by 36 publications

(19 citation statements)

References 23 publications

(18 reference statements)

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“…Again sila‐analogue 3b turned out to possess a significantly higher odor threshold than the parent compound 3a , with 0.085 ng L –1 air being almost about ten times higher than that of 3a (0.0087 ng L –1 air). Concerning structure–odor correlations, silicon compound 3b constitutes the most potent sila‐odorant of the series, and is, in fact, the sila‐odorant with the lowest threshold measured thus far in our laboratory 7,8…”

Section: Resultsmentioning

confidence: 78%

“…The 5‐silacyclohexene skeletons of 1b and 2b were built up by hydroformylation of divinylsilanes, followed by an intramolecular aldol condensation 5,6. As we found in our systematic investigations on silicon‐based odorants,7,8 a sila‐substitution generally much decreases the vapor pressure of odorants. Therefore, in addition to the synthesis and olfactory characterization of the C/Si pairs 1a / 1b and 2a / 2b , it was interesting to prepare the structurally related C/Si pair 3a / 3b as well and to compare its olfactory properties with those of the C/Si pairs 1a / 1b and 2a / 2b (Figure 1).…”

Section: Introductionmentioning

confidence: 74%

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Sila‐α‐galbanone and Analogues: Synthesis and Olfactory Characterization of Silicon‐Containing Derivatives of the Galbanum Odorant α‐Galbanone

et al. 2014

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Silicon compounds 1b–3b are sila‐analogues of the galbanum odorants α‐galbanone (1a), α‐spirogalbanone (2a), and nor‐α‐galbanone (3a), respectively. Sila‐α‐galbanone (1b), sila‐α‐spirogalbanone (2b), and sila‐nor‐α‐galbanone (3b) were synthesized in multistep syntheses in isomerically pure form, starting from Me2SiCl2, (CH2=CH)2SiCl2, and Me2(CH2=CH)SiCl, respectively. Hydroformylation of vinylsilanes, followed by either ring‐closing aldol condensation or ring‐closing alkene metathesis, were the key steps in these syntheses. The C/Si pairs 1a/1b, 2a/2b, and 3a/3b were studied for their olfactory properties. All compounds possess green‐fruity galbanum‐type odors with pineapple aspects and thus are olfactorily related. However, sila‐analogues 1b–3b were found to be weaker than the corresponding parent carbon compounds 1a–3a. This effect is most pronounced for the C/Si pair 2a/2b as indicated by the odor thresholds of 0.023 ng L–1 air (2a) and 3.8 ng L–1 air (2b). However, due to their higher molecular mass, the silicon compounds are less volatile and thus more substantive in functional applications. In contrast to the stable 5‐silacyclohex‐1‐enes 1b and 2b, the 4‐silacyclopent‐1‐ene 3b shows a limited chemical stability. For compound 3a an extremely low odor threshold of 0.0087 ng L–1 air was measured, and the silicon analogue 3b with an odor threshold of 0.085 ng L–1 air is the sila‐odorant with the lowest odor threshold measured so far.

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Section: Resultsmentioning

confidence: 78%

Section: Introductionmentioning

confidence: 74%

Sila‐α‐galbanone and Analogues: Synthesis and Olfactory Characterization of Silicon‐Containing Derivatives of the Galbanum Odorant α‐Galbanone

et al. 2014

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“…For example in odorants design, replacing a carbon atom by a silicon is also a new strategy to create unique signatures in perfumery. [5] More recently, the carbon atom substitution was pushed further and the next crystallogen element, germanium, attracted attention. The C/Ge swap that goes with a further increase of the covalent radius, lipophilicity, and electropositivity was rapidly applied to bioactive compounds [6][7] as well as perfume ingredients or in the design of fungicides.…”

Section: Introductionmentioning

confidence: 99%

Anionic Access to Silylated and Germylated Binuclear Heterocycles

Boddaert

Colleoni

Mistico

et al. 2014

Chemistry A European J

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A simple access to silylated and germylated binuclear heterocycles, based on an original anionic rearrangement, is described. A set of electron-rich and electron-poor silylated aromatic and heteroaromatic substrates were tested to understand the mechanism and the factors controlling this rearrangement, in particular its regioselectivity. This parameter was shown to follow the rules proposed before from a few examples. Then, the effect of the substituents borne by the silicon itself, in particular the selectivity of the ligand transfer, was studied. Additionally, this chemistry was extended to germylated substrates. A hypervalent germanium species, comparable to the putative intermediate proposed with silicon, seems to be involved. However, a pathway implicating the elimination of LiCH2Cl was observed for the first time with this element, leading to unexpected products of the benzo-oxa (or benzo-aza) germol-type.

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“…[5] Generally, more substantive odorants result from such sila-substitutions, and in some cases, such as ford isila-Okoumal [6] and silicon-based patchouli odorants, [7] the odor thresholds improved as well and compensated for the loss in volatility.Int he case of Spirogalbanone (5), however,t he odor detection threshold (th) increased by af actor of about 170 from 0.023 ng L À1 air to 3.8 ng L À1 for the more potent a-isomer. [5] Generally, more substantive odorants result from such sila-substitutions, and in some cases, such as ford isila-Okoumal [6] and silicon-based patchouli odorants, [7] the odor thresholds improved as well and compensated for the loss in volatility.Int he case of Spirogalbanone (5), however,t he odor detection threshold (th) increased by af actor of about 170 from 0.023 ng L À1 air to 3.8 ng L À1 for the more potent a-isomer.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Olfactory Properties of a 6′‐Silasubstituted “Spiro[4.5]‐δ‐Damascone”

Lovchik

Kraft

2017

Chemistry A European J

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The silicon analogue of the potent spirocyclic δ-damascone odorant 6 was synthesized from allyltrichlorosilane (15) and but-2-en-1-ol (16). The latter was transformed to 3-methylpen-4-enenitrile (11) by Saucy-Marbet reaction with ethoxyethane and subsequent treatment with HONH ⋅HCl. The resulting γ,δ-unsaturated nitrile 11 was silylated with 1-allyl-1-chlorosilolane (14), which was prepared from allyltrichlorosilane (15) and the bis-Grignard reagent of 1,4-dichlorobutane. Metathetic ring closure employing the Grubbs I catalyst, followed by DIBAL reduction with non-aqueous work up, Grignard reaction with prop-1-en-1-ylmagnesium bromide, and Attenburrow MnO oxidation concluded the synthesis. The target compound was found to be olfactorily related to the spiro[4.5]-δ-damascone lead, but approximately 900 times weaker. In a type of enol Brook rearrangement, it thermally decomposes however to 3,6-dihydro-2H-1,2-oxasilocine (20), which surprisingly is a damascone odorant as well; although, 12 000 times weaker.

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Odorant Design Based on the Carbon/Silicon Switch Strategy

Cited by 36 publications

References 23 publications

Sila‐α‐galbanone and Analogues: Synthesis and Olfactory Characterization of Silicon‐Containing Derivatives of the Galbanum Odorant α‐Galbanone

Sila‐α‐galbanone and Analogues: Synthesis and Olfactory Characterization of Silicon‐Containing Derivatives of the Galbanum Odorant α‐Galbanone

Anionic Access to Silylated and Germylated Binuclear Heterocycles

Synthesis and Olfactory Properties of a 6′‐Silasubstituted “Spiro[4.5]‐δ‐Damascone”

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