Unsaturated aldehydes as potential lilial replacers

Article abstract of DOI:10.1002/cbdv.201400072

A series of Claisen rearrangements was undertaken in order to find a replacement for Lilial (= 3-(4-(tert-butyl)phenyl)-2-methylpropanal), a high-tonnage perfumery ingredient with a lily-of-the-valley odour, which is a CMR2 material [1]. 5,7,7-Trimethyl-4-methyleneoctanal (10), the synthesis of which is described, became the main lead. It possesses an odour which is very close to that of Lilial but lacks its substantivity. Aldehydes with higher molecular weights than that of 10 were, therefore, synthesised in order to boost substantivity and to understand the structural requirements for a 'Lilial' odour. The aldehydes were obtained via Claisen rearrangements of 'exo-methylidene' vinyl ethers, allenyl vinyl ethers, or allenyl allyl ethers. Alternatively, coupling of terminal alkynes with allyl alcohols led to the desired aldehydes. Derivatives of 10 and their sila analogues were also synthesised. The olfactory properties of all synthesised molecules were evaluated for possible structure-odour relationships (SOR).

Full text of DOI:10.1002/cbdv.201400072

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g-Unsaturated Aldehydes as Potential Lilial Replacers
by Martin Schroeder*, Marion Mathys, Nadja Ehrensperger, and Michelle Bꢀchel
Givaudan Schweiz AG, Fragrance Research, ꢀberlandstrasse 138, CH-8600 Dꢁbendorf
(phone: þ41448242243; fax: þ41448242926; e-mail: martin.schroeder@givaudan.com)
A series of Claisen rearrangements was undertaken in order to find a replacement for Lilial (¼ 3-(4-
(tert-butyl)phenyl)-2-methylpropanal), a high-tonnage perfumery ingredient with a lily-of-the-valley
odour, which is a CMR2 material [1]. 5,7,7-Trimethyl-4-methyleneoctanal (10), the synthesis of which is
described, became the main lead. It possesses an odour which is very close to that of Lilial but lacks its
substantivity. Aldehydes with higher molecular weights than that of 10 were, therefore, synthesised in
order to boost substantivity and to understand the structural requirements for a ꢂLilialꢃ odour. The
aldehydes were obtained via Claisen rearrangements of ꢂexo-methylideneꢃ vinyl ethers, allenyl vinyl
ethers, or allenyl allyl ethers. Alternatively, coupling of terminal alkynes with allyl alcohols led to the
desired aldehydes. Derivatives of 10 and their sila analogues were also synthesised. The olfactory
properties of all synthesised molecules were evaluated for possible structureꢀodour relationships
(SOR).
Introduction. – Lilial (¼ 3-(4-(tert-butyl)phenyl)-2-methylpropanal) is a high-
tonnage, low-cost perfumery ingredient with a lily-of-the-valley odour. It is mainly used
in home and personal care, where it is appreciated for its relatively low odour threshold
of 0.45 ng/l, and its bloom and tenacity. Recent studies have shown that Lilial may
cause harm to the unborn child, which resulted in its classification as a CMR2 material
[1]; restricting its usage. It became, therefore, necessary to search for replacement
odorants. When choosing possible target molecules, one should bear in mind that not
Lilial itself, but tert-butylbenzoic acid, an intermediate of the biodegradation process of
Lilial, is responsible for the adverse effects observed in dogs and rats. Substituted
aromatic aldehydes, which will generate similar degradation products as Lilial, should,
therefore, not be considered as possible Lilial replacement. Modelling experiments
undertaken by Pelzer et al. [2] showed that g,d-unsaturated carbonyl compounds, and
certain secondary and tertiary alcohols are likely to have floral odours. The synthesis of
g,d-unsaturated aldehydes was given priority in this context, since the odour thresholds
of aldehydes tend to be lower than those of the corresponding alcohols or ketones. A
convenient route to this type of aldehydes is the SaucyꢀMarbet variation of the Claisen
rearrangement, in which allyl vinyl ethers undergo thermally induced [3,3] sigmatropic
rearrangements, resulting in g,d-unsaturated aldehydes.
The synthesis of a number of g,d-unsaturated aldehydes via SaucyꢀMarbet
rearrangement will be described herein, together with the discussion of their odour
profiles in relation to their structural properties.
Results and Discussion. – Gansꢀuer et al. [3][4] reported an interesting rearrange-
ment of allyl vinyl ethers, which proceeds via a non-concerted mechanism catalysed by
ꢄ 2014 Verlag Helvetica Chimica Acta AG, Zꢁrich

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CHEMISTRY & BIODIVERSITY – Vol. 11 (2014)
a Lewis acid (Scheme 1). We synthesised a series of aldehydes, 2–5, unfortunately,
none of which possessed the desired lily-of-the-valley note. In our hands, the scope of
this reaction proved to be limited, since the competing [3,3] Claisen rearrange-
ment became the main pathway, if the allylic double bond was not at least trisub-
stituted.
A series of g,d-unsaturated aldehydes, 10–27, was synthesised via [3,3] sigmatropic
SaucyꢀMarbet rearrangement (Scheme 2). The intermediate allyl vinyl ethers were
obtained from readily available unsaturated alcohols or ketones. This allowed us to
obtain aldehydes of wide structural variety. The majority of these aldehydes had green,
aldehydic odours with one notable exception, 5,7,7-trimethyl-4-methyleneoctanal (10),
which is very difficult to distinguish from Lilial on a fresh smelling strip; it became,
therefore, an important lead. Aldehyde 10 was obtained from isononyl aldehyde (6) via
Mannich reaction, reduction of ꢂexo-methylideneꢃ aldehyde 7, and heating the vinyl
ether 8 obtained from 7.
Five analogues, 28–32, of 10 were synthesised to better understand the structural
requirements for a lily-of-the-valley odour (Fig. 1). Variation was introduced at the
pent-4-enal moiety of 10, while its 4,4-dimethylpentan-2-yl moiety was left untouched.
A change of the odour characteristics of 10 was expected when the C¼C bond is
hydrogenated, but it came as a surprise that an additional Me group in a-position to
the C¼C group or further substitution of the ꢂexo-methylideneꢃ group led to drastic
changes of odour properties. It appeared that the pent-4-enal moiety is important for
the lily-of-the-valley odour of 10 and should, therefore, be retained in future target
molecules.
While the odour of 10 is an excellent match for Lilial when fresh, it lacks the
substantivity. Since the substantivity is linked to the vapour pressure of a substance,
lowering the former will result in an increased substantivity. This can be achieved by
increasing the molecular weight of the target molecules. The introduction of further
Scheme 1. Lewis Acid (LA)-Catalysed [1,3] Rearrangement of Allyl Vinyl Ethers

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Scheme 2. Aldehydes via SaucyꢀMarbet Rearrangement

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Fig. 1. Analogues of 5,7,7-trimethyl-4-methylideneoctanal (10)
unsaturation should be beneficial for substantivity and odour threshold as well. Dixneuf
and co-workers. reported the Ru-catalysed coupling of terminal alkynes with allylic
alcohols, resulting in ꢂg-exo-methylideneꢃ aldehydes [5][6]. The ꢂg-exo-methylideneꢃ
aldehydes 35, 40, 43, and 47 were synthesised by applying Dixneufꢃs procedure to
commercially available alkynes (Scheme 3). The aldehydes 40, 42 and 43 were
employed in the synthetic route outlined in Scheme 3 to giving the ꢂg,e-di-exo-
methylideneꢃ aldehydes 39, 46, and 47. The vinyl ether used in this synthetic sequence
was prepared from butyl vinyl ether, catalysed by 4,7-diphenyl-1,10-phenanthroline
(DPP) and palladium trifluoroacetate [7], which reduces the reaction time and the
quantity of vinyl ether engaged. None of the aldehydes synthesised in this context
possessed predominately floral notes. They were mostly described as green, aldehydic
with fruity, often agrestic notes.
A second series of conjugated ꢂexo-methylideneꢃ aldehydes was synthesised from
cyclic ketones (Scheme 4), which were treated with EtMgBr to give the corresponding
ethynyl alcohols 49. These were dehydrated before being coupled with allyl alcohol.
The direct coupling of 49 led to mixed acetals 53 as described by Dixneuf and co-
workers. [8]. The g-unsaturated aldehydes 51 and 54–59 synthesised by this route were
described as green, aldehydic and fruity. Only aldehyde 51 possessed floral notes.
A series of ꢂb-exo-methylideneꢃ aldehydes was synthesised in order to examine the
influence of the distance between ꢂexo-methylideneꢃ and aldehyde group on the overall
odour. These ꢂb-exo-methylideneꢃ aldehydes could conveniently be obtained via Au-
catalysed Claisen rearrangement of allenyl vinyl ether as described by Krafft et al. [9]
(Scheme 5). The vinyl ethers of type 64 in this synthetic sequence were prepared from
ethyl vinyl ethers at room temperature. The allenyl vinyl ethers were too unstable to
support the higher temperatures used in the Pd-catalysed vinylation mentioned above.
Some ethers already partially underwent Claisen rearrangement at room temperature
in absence of the Au-catalyst. The odours of the ꢂb-exo-methylideneꢃ aldehydes
belonged to the same family as similar ꢂg-exo-methylideneꢃ aldehydes. They were also
green and aldehydic, but had more pronounced agrestic notes like mandarin, orange or
citrus. This is probably due the fact that they are long-chain aldehydes such as
undecanal or dodec-2-enal, which have agrestic odours.

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Scheme 3. Di-exo-methylidene Aldehydes from Commercially Available Alkynes
The Claisen rearrangement of allenyl allyl ethers [10] would also lead to ꢂg-
methylideneꢃ aldehydes as outlined in Scheme 6. While the alkynyl allyl ethers 73 were
obtained in good yield, the allenyl allyl ethers 74 turned out to be unstable under the
conditions employed for the rearrangement. The treatment of only two ethers led to a
product. Allenyl allyl ether (79) reacted in an intramolecular DielsꢀAlder reaction to
afford the tricyclic dihydroisobenzofuran 80 during the attempted synthesis of its

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Scheme 4. The Coupling of Allyl Alcohols with Alkynes (conjugated ꢂexo-methylideneꢃ aldehydes from
ketones)
allenyl allyl ether 74.The only other allenyl allyl ether, which did not decompose under
rearrangement conditions, was 81, undergoing an ene-reaction to form hexahydroben-
zofuran 82.
The molecular weight and, therefore, the substantivity of a compound can be
increased by replacing one or more quaternary C-atoms with Si-atom(s). Aldehyde 10
is a perfect candidate for this approach, since it has a quaternary C-atom in its tBu tail.
Tacke and co-workers synthesised the sila analogues of 10 and its derivatives [11]
(Fig. 2), and their odour thresholds and properties were compared with those of C-
analogues. The introduction of the Si-atom improved the substantivity of the molecules
without changing their odour properties significantly. The sila analogues had lower
odour thresholds with the exception of pair 10/83, where the odour threshold of the Si
analogue is nearly twice as high. The aldehyde function, as expected, was essential for
the lily-of-the-valley note of 10. This note was missing in the corresponding alcohols
and ketones, i.e., 85, 87, and 89.

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Scheme 5. The Claisen Rearrangement of Allenyl Vinyl Ethers (conjugated ꢂb-exo-methylideneꢃ
aldehydes from ketones)
Conclusions. – A series of g-unsaturated aldehydes was synthesised and
their odours were evaluated. Most aldehydes were described as green, aldehydic,
often with fruity, agrestic notes, in contrast to Pelzerꢃs postulate [2] that g-unsatur-
ated aldehydes are likely to have floral odours. 5,7,7-Trimethyl-4-methyleneoctanal
(10) was the only aldehyde with the typical lily-of-the-valley note of Lilial. Even
small variations of its structure result in strong changes in odour. The presence of a
short alkane chain in a- or b-position, or moving the ꢂexo-methylideneꢃ group into b-
position shifts the odours of the resulting aldehydes towards fruity or agrestic notes.
Aldehydes, the C(g)¼C(d) bond is part of a six- or five-membered ring, are described
as green and aldehydic, while aldehydes with open-chain C¼C bonds retain their floral
notes, but loose intensity quickly. Introducing Si into the skeleton of 10 and its
derivatives does not change the odour characteristics dramatically, but lowers the
odour intensity significantly. Keeping the pent-4-enal moiety and introducing variation
only at C(4) does not lead to a distinct odour class. It can be concluded that the

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Scheme 6. Aldehyes via Claisen Rearrangement of Allenyl Allyl Ethers
Fig. 2. Sila analogues of 5,7,7-trimethyl-4-methylideneoctanal (10) and its derivatives
pentenal skeleton is too flexible to interact very selectively with particular odour
receptors. It is, therefore, not possible to predict the structural requirements for a floral,
Lilial-like odour.

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Experimental Part
General. Reagents and solvents were purchased from SigmaꢀAldrich and were used without further
purification. Moisture-sensitive reactions were conducted in oven-dried glassware under inert
atmosphere. Flash chromatography (FC): Isco Combi Flash RF with silica cartridges; Thermo Finnigan
Trace GC; Supelco SPB-1; (15 mꢁ0.53 mmꢁ1.5 mm) with He as carrier gas. 1H- and 13C-NMR spectra:
Bruker AVANCE DPX-400 spectrometer, d in ppm rel. to Me4Si, J in Hz. GC/MS: Hewlett-Packard MS
5973 instrument, rel. intensities in % of the base peak. HR-EI-MS: Finnigan MAT 95 (EI: 70 eV).
Olfactory evaluation: 10% soln. in dipropylene glycol (DPG) by two expert perfumers. GCꢀThreshold
determination: different dilutions of the samples substances were injected into a gas chromatograph in
descending order of concentration, until the panellist failed to detect the respective substance at the
sniffing port. The panellists smelled in blind, and pressed a button upon perceiving an odour. If the
recorded time matched the retention time (tR), the sample was further diluted. The last concentration
detected at the correct tR is the individual odour threshold. The reported threshold values are the
geometrical means of the individual odour thresholds of six different panellists.
(3,5,5-Trimethylcyclohex-2-en-1-yl)acetaldehyde (2). 3-(Ethenyloxy)-1,5,5-trimethylcyclohexene (1;
5.0 g, 30 mmol) was dissolved in CH2Cl2 and cooled to 58. One drop of BF3 ·Et2O was added. The mixture
was stirred at 58 for 16 h. The mixture was taken up in CH2Cl2 (100 ml), washed with H2O (3ꢁ100 ml),
and dried (MgSO4). The soln. was filtered, and the solvent was evaporated under reduced pressure. The
crude product was subjected to bulb-to-bulb distillation (1308/0.1 mbar) and further purified via CC to
yield 1.17 g (6 mmol) of a colorless liquid (purity: 90%; yield: 21%). 1H-NMR (400 MHz, CDCl3): 0.90
(s, Me(5’)); 0.95–0.99 (m, HaꢀC(6’)); 0.97 (s, Me(5’)); 1.44–1.50 (m, HbꢀC(6’)); 1.59 (br. d, J¼17.4,
HaꢀC(4’)); 1.65 (s, Me(3’)); 1.82 (br. d, J¼17.4, HbꢀC(4’)); 2.35 (ddd, J¼2.3, 7.7, 16.4, CH2(2)); 2.42 (ddd,
J¼2.3, 6.8, 16.4, HꢀC(1’)); 5.20 (br. s, HꢀC(2’)); 9.80 (dd, J¼2.3, 2.3, HꢀC(1)). 13C-NMR (400 MHz,
CDCl3): 24.2 (q, MeꢀC(3)); 25.7 (q, MeꢀC(5)); 29.3 (d, C(1’)); 30.4 (s, C(5’)); 32.1 (q, MeꢀC(5)); 42.8 (t,
C(6’)); 50.7 (t, C(4’)); 50.7 (t, C(2)); 122.8 (d, C(2’)); 134.9 (s, C(3’)); 203.2 (s, C(1)). EI-MS (70 eV): 166
(31, Mþ ), 151 (33), 123 (52), 122 (54), 107 (100), 91 (35), 95 (43), 81 (70), 67 (36), 41 (28). Odor: green,
aldehydic, slightly hesperidic.
(2,3,4,5,6,7-Hexahydro-1,1,2,3,3-pentamethyl-1H-inden-4-yl)acetaldehyde (3). From 4-(ethenyloxy)-
2,3,4,5,6,7-hexahydro-1,1,2,3,3-pentamethyl-1H-indene as described for 2. Yield: 38% (two isomers, A
1
and B). H-NMR (400 MHz, CDCl3): 0.84 (d, J¼6.6, MeꢀC(2) (A)); 0.87 (d, J¼5.8, MeꢀC(2) (B));
0.83, 0.92, 0.94, 1.01 (4s, Me2C(1), Me2C(3) (A)); 0.83, 0.86, 0.95, 1.00 (4s, Me2C(1), Me2C(3) (B)); 1.47–
1.69 (m, HꢀC(2), CH2(4), CH2(5), CH2(6) (A and B)); 2.45 (ddd, J¼3.0, 10.1, 16.7, HaꢀC(2’) (A)); 2.52
(ddd, J¼2.8, 10.1, 17.2, HaꢀC(2’) (B)); 2.60–2.69 (m, HbꢀC(2’) (A and B)); 2.75–2.81 (m, HꢀC(7) (B));
2.84–2.90 (m, HꢀC(7) (A)); 9.78–9.80 (m, HꢀC(1), (AþB)). 13C-NMR (400 MHz, CDCl3): isomer A:
8.8 (q, MeꢀC(2)); 22.3, 24.4, 27.4, 28.1 (4s, Me2C(1), Me2C(3)); 19.0 (t, C(6)); 22.0 (t, C(7)); 28.1 (d,
C(4)); 46.4 (s, C(3)); 46.8 (s, C(1)); 48.8 (t, C(2’)); 54.7 (d, C(2)); 140.9 (s, C(7a)); 143.0 (s, C(3a)); 203.4
(d, C(1’)). 13C-NMR (400 MHz, CDCl3): isomer B: 8.5 (q, MeꢀC(2)); 21.9, 22.9, 28.4, 28.9 (4s, Me2C(1),
Me2C(3)); 18.0 (t, C(6)); 21.5 (t, C(7)); 28.4 (d, C(4)); 46.4 (s, C(3)); 47.9 (s, C(1)); 48.9 (t, C(2’)); 53.2 (d,
C(2)); 140.9 (s, C(7a)); 144.1 (s, C(3a)); 203.2 (d, C(1’)). EI-MS (70 eV): isomer A: 234 (11, Mþ ), 219
(51, [Mꢀ15]þ ), 190 (66), 175 (100), 133 (17), 119 (25), 105 (32), 91 (26), 79 (15), 55 (19). EI-MS
(70 eV): isomer B: 234 (9, Mþ ), 219 (36, [Mꢀ15]þ ), 190 (54), 175 (100), 133 (14), 119 (18), 105 (22), 91
(21), 79 (10), 55 (15). Odor: woody, warm, powdery, musky.
(3-Methyl-5-propylcyclohex-2-en-1-yl)acetaldehyde (4). From ethenyl 3-methyl-5-propylcyclohex-2-
en-1-yl ether as described for 2. Yield: 50%. 1H-NMR (400 MHz, CDCl3): 0.89 (t, J¼7.3, Me(9’)); 1.20–
1.45 (m, CH2(6’), CH2(7’), CH2(8’)); 1.53–1.67 (m, HaꢀC(4), HꢀC(5)); 1.64 (s, MeꢀC(3’)); 1.94–2.01 (m,
HbꢀC(4)); 2.38 (ddd, J¼2.0, 7.0, 16.8, HaꢀC(2)); 2.44 (ddd, J¼2.0, 6.7, 16.8, HbꢀC(2)); 2.69–2.71 (m,
HꢀC(1’)); 5.28–5.32 (m, HꢀC(2’)); 9.78 (dd, J¼2.0, 2.0, HꢀC(1)). 13C-NMR (400 MHz, CDCl3): 14.2 (q,
C(9’)); 20.1 (t, C(8’)); 23.8 (q, MeꢀC(3)); 28.8 (d, C(5’)); 29.6 (d, C(1’)); 33.6 (t, C(6’)); 36.5 (t, C(4’)); 38.0
(t, C(7’)); 50.1 (t, C(2)); 123.2 (d, C(2’)); 135.0 (s, C(3’)); 202.7 (d, C(1)). EI-MS (70 eV): 180 (25, Mþ ),
137 (58), 135 (35), 95 (75), 93 (100), 91 (38), 81 (91), 67 (38), 55 (38), 41 (35). Odor: Green, aldehydic,
animalic, costus.

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3-(4,6,6-Trimethylcyclohexa-1,3-dien-1-yl)propanal (5). From 4-[(ethenyloxy)methyl]-1,5,5-trime-
thylcyclohexa-1,3-diene as described for 2. Yield: 90%. 1H-NMR (400 MHz, CDCl3): 0.99 (s, Me2C(6’));
1.09 (br. s, MeꢀC(4’)); 1.96 (br. s, CH2(5’)); 2.40 (br. t, J¼7.6, CH2(3)); 2.60 (dt, J¼1.8, 7.6, CH2(2));
5.44–5.47 (m, HꢀC(2’)); 5.58–5.62 (m, HꢀC(3’)); 9.79 (t, J¼1.8, HꢀC(1)). 13C-NMR (400 MHz, CDCl3):
23.6 (q, MeꢀC(4)); 23.6 (t, C(3)); 26.2 (q, Me2C(6)); 34.9 (s, C(6’)); 42.2 (t, C(2)); 45.6 (t, C(5’)); 118.6 (d,
C(3’)); 118.8 (d, C(2’)); 134.1 (s, C(4’)); 141.9 (s, C(1’)); 202.9 (d, C(1)). EI-MS (70 eV): 178 (22, Mþ ),
121 (23), 120 (16), 119 (100), 107 (8), 105 (15), 91 (15), 79 (7), 77 (9), 41 (7). Odor: floral, aldehydic,
minty, medicinal.
3,5,5-Trimethyl-2-methylidenehexanal (7). 3,5,5-Trimethylhexanal (6; 25.7 g, 181 mmol) was added
to HCHO at 36% in H2O (21.5 g, 258 mmol). The emulsion was heated to reflux (1108) under vigorous
stirring. Bu2NH (1.3 g, 10 mmol) was added, and stirring was continued for further 2 h. The mixture was
cooled to r.t. and diluted with 200 ml of tBuOMe. The layers were separated, and the org. layer was dried
(MgSO4) and filtered. The solvent was removed under reduced pressure. The crude product was
subjected to bulb-to-bulb distillation (908/10 mbar) to yield 24.0 g (156 mmol) of a colorless liquid (yield:
86%). 1H-NMR (400 MHz, CDCl3): 0.88 (s, Me3C(5)); 1.08 (d, J¼6.8, MeꢀC(3)); 1.31 (dd, J¼5.1, 13.9,
HaꢀC(4)); 1.59 (dd, J¼6.8, 13.9, HbꢀC(4)); 2.85 (ddq, J¼5.1, 6.8, 13.9, HꢀC(3)); 5.96 (s, 1 H of ¼CH2));
6.29 (s, 1 H of ¼CH2)); 9.53 (s, HꢀC(1)). 13C-NMR (400 MHz, CDCl3): 23.7 (q, MeꢀC(3)); 28.3 (d, C(3));
30.4 (q, Me3C(5)); 31,7 (s, C(5)); 50.2 (t, C(4)); 133.6 (t, CH2¼C(2)); 158.0 (s, C(2)); 195.0 (d, C(1)). EI-
MS (70 eV): 139 (30, [Mꢀ15]þ ), 121 (37), 98 (34), 97 (54), 84 (22), 83 (30), 71 (20), 69 (22), 57 (100),
55 (36), 43 (38), 41 (48). Odour: green, fatty, sappy, woody, dry, bark like.
3,5,5-Trimethyl-2-methylidenehexan-1-ol (8). LiAlH4 (0.8 g, 20 mmol) was placed under Ar in 100 ml
of THF and cooled to 58. Compound 7 (10.0 g, 65 mmol) was added at this temp. during 30 min. Stirring
was continued for further 30 min. H2O (0.8 ml), NaOH (0.8 ml; aq. soln. at 15%), and H2O (2.4 ml) were
added at 58. Stirring was continued for 20 min until the grey suspension turned white. The suspension was
filtered, and the solvent was evaporated under reduced pressure to yield 10.0 g (64 mmol) of a colorless
liquid (yield: 98%). 1H-NMR (400 MHz, CDCl3): 0.90 (br. s, Me3C(5)); 1.08 (d, J¼7.1, MeꢀC(3)); 1.20
(dd, J¼5.6, 13.9, HaꢀC(4)); 1.52 (dd, J¼5.8, 13.9, HbꢀC(4)); 2.3 (m, HꢀC(3)); 4.13 (br. s, HꢀC(1)); 4.91
(m, 1 H of ¼CH2)); 5.00 (br. s, 1 H of ¼CH2)). 13C-NMR (400 MHz, CDCl3): 23.7 (q, MeꢀC(3)); 30.3 (q,
Me3C(5)); 31.6 (s, C(5)); 34.1 (d, C(3)); 50.2 (t, C(4)); 64.7 (t, C(1)); 107.7 (t, H2C¼C(2)); 156.3 (s, C(2)).
EI-MS (70 eV): 156 (1, Mþ ), 123 (7), 85 (9), 81 (14), 71 (16), 69 (25), 57 (100), 55 (16), 43 (35), 41 (34).
Odour: herbal, camphoraceous, minty, animalic.
2-[(Ethenyloxy)methyl]-3,5,5-trimethylhex-1-ene (9). A mixture of ethenyl ethyl ether (69.2 g,
960 mmol), 8 (10.0 g, 64 mmol), and Hg(OAc)2 (4.1 g, 12.8 mmol) was stirred at r.t. for 16 h. The mixture
was washed with H2O (3ꢁ200 ml). The aq. layers were united and extracted with tBuOMe (2ꢁ100 ml).
The combined org. phases were dried (MgSO4) and filtered. The solvent and the excess of ethenyl ethyl
ether were evaporated under reduced pressure. The crude product was subjected to bulb-to-bulb
distillation (1308/10 mbar) to yield 8.0 g (44 mmol) of a colorless liquid (yield: 69%). 1H-NMR
(400 MHz, CDCl3): 0.93 (s, Me3C(5)); 1.12 (d, J¼6.8, MeꢀC(3)); 1.22 (dd, J¼5.6, 14.2, HaꢀC(4)); 1.56
(dd, J¼5.6, 14.2, HbꢀC(4)); 2.23 (m, HꢀC(3)); 4.04 (dd, J¼2.0, 6.8, HaꢀC(2’)); 4.22 (br. s, CH2(1)); 4.26
(dd, J¼2.0, 14.2, HbꢀC(2’)); 5.01 (m, 1 H of ¼CH2)); 5.05 (m, 1 H of ¼CH2)); 6.49 (dd, J¼6.8, 14.2,
HꢀC(1’)). 13C-NMR (400 MHz, CDCl3): 23.5 (q, C(3)); 30.3 (q, Me3C(5)); 31.6 (s, C(5)); 34.0 (d, C(3));
50.7 (t, C(4)); 70.4 (t, C(1)); 87.4 (t, C(2’)); 110.6 (t, CH2¼C(2)); 151.7 (s, C(2)); 152.1 (d, C(1’)). EI-MS
(70 eV): 139 (2, [Mꢀ43]þ ), 123 (7), 98 (7), 97 (6), 85 (11), 81 (11), 71 (21), 67 (21), 57 (100), 55 (20), 43
(31), 41 (36). Odour: green, carrot.
5,7,7-Trimethyl-4-methylideneoctanal (10). Compound 9 (1.0 g, 5.5mmol) was heated under Ar for
4 h at 1608. The crude product was cooled to r.t. and purified via CC to yield 0.4 g (2.2 mmol) of a
colorless liquid (yield: 40%). 1H-NMR (400 MHz, CDCl3): 0.91 (s, Me3C(7)); 1.07 (d, J¼7.1, MeꢀC(5));
1.19 (dd, J¼5.3, 14.2, HaꢀC(6)); 1.51 (dd, 6.1, 14.2, HbꢀC(6)); 2.31 (m, HꢀC(5)); 2.37 (m, CH2(3)); 2.62
(m, CH2(2)); 4.63 (br. s, 1 H of H2C¼C(4)); 4.87 (br. s, 1 H of H2C¼C(4)); 9.81 (t, J¼1.8, HꢀC(1)).
13C-NMR (400 MHz, CDCl3): 23.4 (q, C(5)); 25.5 (t, C(3)); 30.3 (q, Me3C(7)); 31.6 (s, C(7)); 42.4 (t,
C(2)); 49.8 (t, C(6)); 108.3 (t, H2C¼C(4)); 154.8 (s, C(4)); 202.7 (s, C(1)). EI-MS (70 eV): 167 (1, [Mꢀ
15]þ ), 149 (2), 126 (13), 108 (31), 107 (13), 91 (24), 84 (27), 83 (19), 82 (16), 73 (18), 71 (19), 69 (14), 57
(100), 55 (38), 43 (32), 41 (39). Odour: aldehydic, green, fatty, rubbery with Bourgeonal aspects.

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(2-Pentylcyclopent-2-en-1-yl)acetaldehyde (11). From 5-(ethenyloxy)-1-pentylcyclopentene as de-
scribed for 10. Yield: 70%. 1H-NMR (400 MHz, CDCl3): 0.91 (t, J¼6.8, Me(10’)); 1.24–1.57 (m,
HaꢀC(5’), CH2(7’), CH2(8’), CH2(9’)); 2.85–2.34 (m, HaꢀC(2), CH2(4’), HbꢀC(5’), CH2(6)); 2.63 (ddd,
J¼1.8, 4.0, 16.2, HbꢀC(2)); 2.97–3.05 (m, HꢀC(1’)); 5.40–5.43 (m, HꢀC(3’)); 9.80 (dd, J¼1.8, 2.5,
HꢀC(1)). 13C-NMR (400 MHz, CDCl3): 14.4 (q, C(10’)); 22.9 (t, C(9’)); 27.7 (t, C(5’)); 29.4 (t, C(7’)); 30.8
(t, C(4’)); 31.1 (t, C(8’)); 32.1 (t, C(6’)); 41.8 (d, C(1’)); 48.3 (t, C(2)); 125.0 (d, C(3’)); 146.1 (s, C(2’));
203.2 (d, C(1)). EI-MS (7 eV): 154 (7), 97 (14), 85 (6), 84 (100), 83 (23), 69 (6), 56 (10), 55 (20), 41 (17),
39 (7). Odor: aldehydic, green, metallic, carrot like, fruity.
2-(Cyclopent-1-en-1-yl)hexanal (12). From (2Z)-1-(ethenyloxy)-2-pentylidenecyclopentane as de-
scribed for 10. Yield: 48%. 1H-NMR (400 MHz, CDCl3): 0.89 (t, J¼7.1, Me(7)); 1.18–1.46 (m, CH2(4’),
CH2(4), CH2(5), CH2(6)); 1.82–1.89 (m, CH2(3’)); 2.26–2.32 (m, CH2(5’)); 2.41–2.45 (m, CH2(2)); 2.82
(tt, J¼7.1, 7.1, HꢀC(3)); 5.40–5.44 (m, HꢀC(2’)); 9.67 (dd, J¼2.8, 2.8, HꢀC(1)). 13C-NMR (400 MHz,
CDCl3):14.3 (q, C(7)); 23.1 (t, C(4)); 23.6 (t, C(6)); 29.6 (t, C(5)); 32.2 (t, C(3’)); 32.4 (t, C(5’)); 33.6 (t,
C(4’)); 33.2 (d, C(3)); 47.9 (t, C(2)); 125.9 (d, C(1’)); 146.0 (s, C(2’)); 203.2 (d, C(1)). EI-MS (70 eV): 180
(14, Mþ ), 151 (33), 123 (30), 109 (39), 95 (100), 93 (32), 81 (45), 79 (46), 77 (24), 67 (60). Odor: green,
aldehydic, metallic, fatty.
3-(Cyclopent-1-en-1-yl)-5-methylhexanal (13). From ethenyl (2Z)-2-(3-methylbutylidene)cyclopen-
1
tyl ether as described for 10. Yield: 62%. H-NMR (400 MHz, CDCl3): 0.88 (d, J¼6.6, Me2C(5)); 1.14
(ddd, J¼5.8, 8.3, 13.4, HaꢀC(4)); 1.38 (ddd, J¼5.6, 9.4, 13.4, HbꢀC(4)); 1.44–1.58 (m, HꢀC(5)); 1.79–
1.87 (m, CH2(4’)); 2.15–2.22 (m, CH2(3’)); 2.24 ꢀ2.30 (m, CH2(5’)); 2.36–2.40 (m, CH2(2)); 2.88 (m,
HꢀC(3)); 5.42–5.45 (m, HꢀC(2’)); 9.65 (dd, J¼2.8, 2.8, HꢀC(1)). 13C-NMR (400 MHz, CDCl3): 22.4 (q,
MeꢀC(5)); 23.5 (q, MeꢀC(5)); 23.6 (t, C(4’)); 25.8 (d, C(5)); 31.8 (t, C(5’)); 32.4 (t, C(3’)); 34.2 (d, C(3));
43.3 (t, C(4)); 48.2 (t, C(2)); 126.1 (d, C(1’)); 145.9 (s, C(2’)); 203.1 (d, C(4)). MS (70 eV): 180 (8, Mþ ),
109 (17), 96 (18), 95 (100), 93 (27), 91 (20), 81(29), 79 (29), 77 (18), 67 (39), 41 (19). Odor: green,
aldehydic, metallic, fatty, buttery.
2-[2-(3-Methylbutyl)cyclopent-2-en-1-yl]acetaldehyde (14). From ethenyl 2-(3-methylbutyl)cyclo-
pent-2-en-1-yl ether as described for 10. Yield: 64%. 1H-NMR (400 MHz, CDCl3): 0.90 (d, J¼6.6,
MeꢀC(8’)); 0.91 (d, J¼6.6, MeꢀC(8’)); 1.27–1.41 (m, CH2(7’)); 1.9–1.60 (m, HꢀC(8’), HaꢀC(5’)); 1.87–
2.23 (m, CH2(6’), HbꢀC(5’)); 2.24 ꢀ2.34 (m, CH2(2), HaꢀC(4’)); 2.63 (ddd, J¼2.0, 4.0, 16.2, HbꢀC(4’));
2.97–3.06 (m, HꢀC(1’)); 5.39–5.40 (m, HꢀC(3’)); 9.80 (dd, J¼1.8, 2.8, HꢀC(1)). 13C-NMR (400 MHz,
CDCl3):22.7 (q, MeꢀC(8’)); 23.2 (q, MeꢀC(8’)); 27.2 (t, C(5’)); 28.3 (d, C(8’)); 30.8 (t, C(4’)); 31.2 (t,
C(6’)); 37.2 (t, C(7’)); 41.8 (d, C(1’)); 48.2 (t, C(2)); 124.8 (d, C(3’)); 146.3 (s, C(2’)); 203.3 (d, C(1)). EI-
MS (70 eV): 180 (2, Mþ ), 136 (28), 95 (43), 91 (21), 81 (40), 80 (100), 79 (37), 77 (23), 67 (28), 41 (24).
Odor: aldehydic, green, sappy, citrus.
4-Benzylpent-4-enal (15). From 2-benzylprop-2-en-1-yl ethenyl ether as described for 10. Yield:
55%. 1H-NMR (400 MHz, CDCl3): 2.34 (br. t, J¼7.1, CH2(3)); 2.57 (dt, J¼1.8, 7.1, CH2(2)); 3.40 (br. s,
CH2(5)); 4.87 (br. s, 1 H of CH2¼C(4)); 4.89 (br. s, 1 H of CH2¼C(4)); 7.20–7.25 (m, HꢀC(2’), HꢀC(6’));
7.23 (m, HꢀC(4’)); 7.31–7.35 (m, HꢀC(3’), HꢀC(5’)); 9.74 (t, J¼1.8, HꢀC(1)). 13C-NMR (400 MHz,
CDCl3): 27.9 (t, C(3)); 42.1 (t, C(2)); 43.8 (t, C(5)); 112.4 (t, CH2¼C(4)); 126.7 (d, C(4’)); 128.8 (d, C(2’),
C(6’)); 129.3 (d, C(3’), C(5’)); 139.6 (s, C(1’)); 147.3 (s, C(4)); 147.3 (s, C(4)); 202.4 (s, C(1)). EI-MS
(70 eV): 174 (14, Mþ ), 156 (33), 181 (29), 129 (37), 128 (25), 118 (33), 117 (70), 115 (56), 91 (100), 65
(24). Odor: aldehydic, fatty, citrus.
4-Methylidene-5-phenylhexanal (16). From ethenyl 2-methylidene-3-phenylbutyl ether as described
for 10. Yield: 31%. 1H-NMR (400 MHz, CDCl3): 1.42 (d, J¼7.1, Me(6)); 2.17–2.31 (m, CH2(3)); 2.48–
2.54 (m, CH2(2)); 3.45 (q, J¼7.1, HꢀC(5)); 4.92 (br. s, 1 H of CH2¼C(4)); 5.08 (br. s, 1 H of CH2¼C(4));
7.21–7.26 (m, HꢀC(2’), HꢀC(4’), HꢀC(6’)); 7.30–7.34 (m, HꢀC(3’), HꢀC(5’)); 9.68 (t, J¼1.8, HꢀC(1)).
13C-NMR (400 MHz, CDCl3): 21.0 (q, C(6)); 27.5 (t, C(3)); 42.4 (t, C(2)); 46.1 (d, C(5)); 115.9 (t,
H2C¼C(4)); 126.8 (d, C(4’)); 127.9 (C(2’), C(6’)); 128.9 (C(3’), C(5’)); 145.2 (s, C(4)); 151.5 (s, C(1’));
202.5 (s, C(1)). EI-MS (70 eV): 188 (12, Mþ ), 132 (56), 131 (71), 129 (100), 128 (38), 117 (49), 115 (45),
105 (81), 91 (64), 77 (40). Odor: floral, green, weak.
4-(3-Methyl-5-propylcyclohex-2-en-1-yl)pent-4-enal (17). From ethenyl 2-(3-methyl-5-propylcyclo-
hex-2-en-1-yl)prop-2-en-1-yl ether as described for 10. Yield: 72%. 1H-NMR (400 MHz, CDCl3): 0.89 (t,
J¼7.1, Me(9’)); 1.20–1.40 (m, CH2(7’), CH2(8’)); 1.54–1.65 (m, HaꢀC(4’), CH2(6’)); 1.70 (br. s,

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CHEMISTRY & BIODIVERSITY – Vol. 11 (2014)
MeꢀC(3’)); 1.99 (br. d, J¼17.63, HbꢀC(4’)); 2.30 ꢀ2.51 (m, CH2(3)); 2.58–2.65 (m, CH2(2)); 2.72–2.78
(m, HꢀC(5’)); 4.79 (br. s, CH2¼C(4)); 5.26 (br. s, HꢀC(2’)); 9.80 (t, J¼1.5, HꢀC(1)). 13C-NMR
(400 MHz, CDCl3): 14.7 (q, C(9’)); 20.5 (t, C(8’)); 24.2 (q, MeꢀC(3’)); 27.6 (t, C(3)); 29.6 (d, C(5’)); 33.0
(t, C(6’)); 37.3 (t, C(4’)); 38.6 (t, C(7’)); 41.0 (d, C(1’)); 42.7 (t, C(2)); 111.5 (t, CH2¼C(4)); 123.0 (d, C(2’));
135.6 (s, C(3’)); 150.5 (s, C(4)); 202.7 (d, C(1)). EI-MS (70 eV): 220 (20, Mþ ), 164 (98), 121 (56), 107
(62), 105 (53), 93 (100), 91 (79), 79 (54), 55 (56), 41 (47). Odor: sweet, valerian like, rosy, leathery,
winey, fruity.
2-[6-(Propan-2-yl)cyclohex-2-en-1-yl]acetaldehyde (18). From 3-(ethenyloxy)-6-(propan-2-yl)cy-
clohexene as described for 10. Yield: 55%. 1H-NMR (400 MHz, CDCl3): 0.84 (d, J¼6.8, MeꢀC(7’)); 0.91
(d, J¼6.8, MeꢀC(7’)); 1.13–1.20 (m, HaꢀC(5’)); 1.37–1.44 (m, HꢀC(6’)); 1.62–1.81 (m, HaꢀC(4’),
HbꢀC(5’)); 1.93–2.06 (m, HbꢀC(4’), HꢀC(7’)); 2.38 (ddd, J¼2.8, 7.6, 16.2, HaꢀC(2)); 2.55 (ddd, J¼2.0,
5.6, 16.2, HbꢀC(2)); 2.59–2.67 (m, HꢀC(1’)); 5.51–5.56 (m, HꢀC(2’)); 5.71–5.77 (m, HꢀC(3’)); 9.79 (dd,
J¼2.0, 2.8, HꢀC(1)). 13C-NMR (400 MHz, CDCl3): 17.8 (q, MeꢀC(7’)); 21.2 (t, C(4’)); 22.0 (q,
MeꢀC(7’)); 24.7 (t, C(5’)); 27.7 (d, C(7’)); 33.3 (d, C(1’)); 44.5 (d, C(6’)); 49.1 (t, C(2)); 128.6 (d, C(3’));
130.1 (d, C(2’)); 203.7 (d, C(1)). EI-MS (70 eV): 166 (17, Mþ ), 122 (36), 96 (31), 95 (30), 81 (39), 79
(100), 78 (33), 77 (29), 67 (74), 41 (37). Odor: green, resinous, fatty, carrot.
3-(Cyclohex-1-en-1-yl)heptanal (19). From (2E)-1-(ethenyloxy)-2-pentylidenecyclohexane as de-
scribed for 10. Yield: 67%. 1H-NMR (400 MHz, CDCl3): 0.89 (t, J¼7.1, Me(7)); 1.15 ꢀ1.45 (m, HaꢀC(4),
CH2(5), CH2(6), HaꢀC(5’)); 1.51–1.64 (m, HbꢀC(4), CH2(4’), Hbꢀ(5’)); 1.83–1.89 (m, HaꢀC(3’),
HaꢀC(6’)); 1.96–2.03 (m, HbꢀC(3’), HbꢀC(6’)); 2.35 (ddd, J¼2.5, 6.6, 15.7, HaꢀC(2)); 2.42 (ddd, J¼3.0,
8.3, 15.7, HbꢀC(2)); 2.48–2.57 (m, HꢀC(3)); 5.46–5.50 (m, HꢀC(2’)); 9.66 (dd, J¼2.5, 3.0, HꢀC(1)).
13C-NMR (400 MHz, CDCl3): 14.4 (q, C(7)); 23.0 (2t, C(3’), C(4’)); 23.2 (t, C(6)); 25.1 (t, C(6’)); 25.5 (t,
C(5’)); 29.8 (t, C(5)); 33.3 (t, C(4)); 42.5 (d, C(3)); 48.0 (t, C(2)); 123.7 (d, C(2’)); 138.5 (s, C(1’)); 203.5
(d, C(1)). EI-MS (70 eV): 194 (7, Mþ ), 137 (66), 109 (68), 95 (75), 93 (61), 91 (60), 81(84), 79 (86), 67
(100), 41 (60). Odor: green, aldehydic, metallic.
3-(Cyclohex-1-en-1-yl)-5-methylhexanal (20). From ethenyl (2E)-2-(3-methylbutylidene)cyclohexyl
ether as described for 10. Yield: 61%. 1H-NMR (400 MHz, CDCl3): 0.89 (d, J¼6.8, Me2C(5)); 1.08 (ddd,
J¼5.6, 8.8, 13.6, HaꢀC(4)); 1.38 (ddd, J¼5.1, 9.9, 13.6, HbꢀC(4)); 1.46–1.63 (m, HꢀC(5), CH2(4’),
CH2(5’)); 1.82–1.89 (m, HaꢀC(3’), HaꢀC(6’)); 1.95–202 (m, HbꢀC(3’), HbꢀC(6’)); 2.31 (ddd, J¼2.3, 6.3,
15.7, HaꢀC(2)); 2.39 (ddd, J¼3.0, 8.6, 15.7, HbꢀC(2)); 2.61–2.70 (m, HꢀC(3)); 5.49–5.53, HꢀC(2’)); 9.65
(dd, J¼2.3, 3.0, HꢀC(1)). 13C-NMR (400 MHz, CDCl3): 22.3 (q, Me2C(5)); 23.0 (t, C(5’)); 23.2 (t, C(4’));
24.7 (t, C(3’)); 25.5 (t, C(6’)); 25.7 (d, C(5)); 40.4 (d, C(3)); 42.9 (t, C(4)); 48.2 (t, C(2)); 123.9 (d, C(2’));
138.4 (s, C(1’)); 203.4 (d, C(1)). EI-MS (70 eV): 194 (8, Mþ ), 138 (50), 109 (100), 107 (52), 95 (72), 94
(72), 91 (60), 81 (70), 79 (77), 67 (91). Odor: weak, green, hay.
5-Methyl-4-methylidene-3-(2-methylpropyl)hexanal (21). From ethenyl (2E)-5-methyl-2-(propan-2-
1
yl)hex-2-en-1-yl ether as described for 10. Yield: 94%. H-NMR (400 MHz, CDCl3): 0.90 (d, J¼6.6,
MeꢀC(2’)); 0.91 (d, J¼6.3, MeꢀC(2’)); 1.06 (d, J¼6.8, MeꢀC(5)); 1.06 (d, J¼6.8, MeꢀC(5)); 1.20 (ddd,
J¼7.1, 7.1, 13.9, 1 H of CH2(1’)); 1.40 (ddd, J¼6.6, 7.8, 13.9, 1 H of CH2(1’)); 1.51–1.65 (m, HꢀC(2’));
2.16–2.26 (m, HꢀC(5)); 2.42 (ddd, J¼2.3, 6.6, 16.2, HaꢀC(2)); 2.49 (ddd, J¼2.5, 7.6, 16.2, HbꢀC(2));
2.65–2.74 (m, HꢀC(3)); 4.80 (s, 1 H of CH2¼C(4)); 4.91 (s, 1 H of CH2¼C(4)); 9.68 (dd, J¼2.3, 2.5,
HꢀC(1)). 13C-NMR (400 MHz, CDCl3): 23.0 (q, MeꢀC(5)); 23.1 (q, MeꢀC(5)); 23.1 (q, MeꢀC(2’)); 23.2
(q, MeꢀC(2’)); 25.8 (d, C(2’)); 23.0 (d, C(5)); 37.8 (d, C(3)); 45.0 (t, C(1’)); 49.1 (t, C(2)); 108.1 (d,
H2C¼C(4)); 158.7 (s, C(4)); 203.1(d, C(1)). EI-MS (70 eV): 167 (3, [Mꢀ15]þ ), 108 (31), 97 (71), 84
(30), 83 (50), 70 (30), 69 (54), 55 (100), 43 (33), 41 (57). Odor: green, fatty, fruity.
3-Ethyl-4-methylpent-4-enal (22). From ethenyl (2E)-2-methylpent-2-en-1-yl ether as described for
10. Yield: 60%. 1H-NMR (400 MHz, CDCl3): 0.86 (t, J¼7.3, Me(2’)); 1.44 (dq, J¼7.3, 7.3, CH2(1’)); 1.66
(s, Me(5)); 2.42–2.45 (m, CH2(2)); 2.54–2.61 (m, HꢀC(3)); 4.77 (br. s, 1 H of CH2¼C(4)); 4.82 (br. s, 1 H
of CH2¼C(4)); 9.68 (t, J¼2.5, HꢀC(1)). 13C-NMR (400 MHz, CDCl3): 11.8 (q, 2 C(2’)); 19.2 (q, 2 C(5));
26.3 (t, C(1’)); 43.6 (d, C(3)); 47.6 (t, C(2)); 112.7 (t, H2C¼C(4)); 146.2 (s, C(4)); 202.9 (d, C(1)). EI-MS
(70 eV): 111 (14, [Mꢀ15]þ ), 97 (22), 84 (59), 69 (100), 67 (31), 56 (16), 55 (94), 53 (20), 41 (82), 39
(33). Odor: too weak, too volatile.
5,7,7-Trimethyl-3-[(1E)-prop-1-en-1-yl]octanal (23). From (3E)-2-(ethenyloxy)-6,8,8-trimethylnon-
3-ene as described for 10. Yield: 56% (two isomers; ratio 1:1). 1H-NMR (400 MHz, CDCl3): 0.89, 0.90 (s,

CHEMISTRY & BIODIVERSITY – Vol. 11 (2014)
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Me3C(7)); 0.91, 0.96 (2d, J¼6.6, MeꢀC(5)); 0.99–1.36 (m, CH2(4), CH2(6)); 1.45 ꢀ1.58 (m, HꢀC(5));
1.64–1.68 (m, Me(3’)); 2.28–2.43 (m, CH2(2)); 2.60–2.69 (m, HꢀC(3)); 5.21, 5.26 (2dq, J¼15.4, 1.8, and
J¼15.4, 1.5, resp., HꢀC(2’)); 5.47, 5.51 (2ddq, J¼6.3, 15.4, 0.8, HꢀC(1’)); 9.70, 9.71 (2t, J¼2.5 and J¼2.3,
resp., HꢀC(1)).13C-NMR (400 MHz, CDCl3):18.2, 18.3 (2q, C(3’)); 22.3, 23.6 (2q, MeꢀC(5)); 26.8, 27.1
(2d, C(5)); 30.4, 30.7 (2q, Me3C(7)); 31.6, 31.7 (2s, C(7)); 35.7, 36.0 (2d, C(3)); 45.7, 45.8 (2t, C(4)); 49.5
50.3 (2t, C(2)); 51.2, 52.3 (2t, C(6)); 126.3, 126.6 (2d, C(2’)); 133.9, 134.6 (2d, C(1’)); 203.3, 203.4 (2d,
C(1)). EI-MS (70 eV): 159 (1, [Mꢀ15]þ ), 139 (14), 98 (19), 97 (57), 95 (21), 83 (18), 69 (24), 57 (100),
55 (18), 41 (31). EI-MS (70 eV): 139 (14), 111 (11), 98 (18), 97 (57), 95 (21), 83 (18), 69 (25), 57 (100),
55 (18), 41 (30). Odor: aldehydic, fatty, floral, green.
5,9-Dimethyl-4-methylidenedec-8-enal (24). From 3,7-dimethyl-2-methylideneoct-6-en-1-yl ethenyl
ether as described for 10. Yield: 64%. 1H-NMR (400 MHz, CDCl3): 1.05 (d, J¼6.8, MeꢀC(5)); 1.29–1.38
(m, HaꢀC(6)); 1.44–1.53 (m, HbꢀC(6)); 1.60 (br. s, MeꢀC(9)); 1.69 (br. s, MeꢀC(9)); 1.93 (br. dt, J¼7.3,
7.3, CH2(7)); 2.15 (tq, J¼7.1, 6.8, HꢀC(5)); 2.31–2.37 (m, CH2(3)); 2.60 (dt, J¼1.5, 7.6, CH2(2)); 4.69–
4.70 (m, 1 H of CH2¼C(4)); 4.82–4.83 (m, 1 H of CH2¼C(4)); 5.07–5.12 (m, HꢀC(8)); 9.80 (t, J¼1.5,
HꢀC(1)). 13C-NMR (400 MHz, CDCl3): 18.1 (q, MeꢀC(5)); 20.4 (q, Me2C(9)); 25.9 (t, C(3)); 26.3 (t,
C(7)); 36.0 (t, C(6)); 40.3 (d, C(5)); 42.4 (t, C(2)); 108.7 (t, H2C¼C(4)); 124.9 (d, C(8)); 131.8 (s, C(9));
152.8 (s, C(4)); 202.6 (d, C(1)). EI-MS (70 eV): 150 (13, [Mꢀ44]þ ), 107 (12), 83 (14), 82 (100), 81 (14),
69 (18), 67 (36), 55 (40), 53 (10), 41 (37). Odor: aldehydic, green, metallic, citrus, mandarin, coriander
leaf.
4-Methylidenetridec-12-enal (25). From ethenyl 2-methylideneundec-10-en-1-yl ether as described
for 10. Yield: 69%. 1H-NMR (400 MHz, CDCl3): 1.26–1.47 (m, CH2(6), CH2(7), CH2(8), CH2(9),
CH2(10)); 2.00–2.08 (m, CH2(5), CH2(1)); 2.35 (br. t, J¼7.3, CH2(3)); 2.57 (dt, J¼1.8, 7.3, CH2(2)); 4.70
(br. s, 1 H, 1 H of H2C¼C(4)); 4.77 (br. s, 1 H of H2C¼C(4)); 4.93 (ddt, J¼2.3, 10.1, 1.5, HaꢀC(13)); 4.98
(ddt, J¼2.3, 17.2, 1.5, HbꢀC(13)); 5.81 (ddt, 10.1, 17.2, 6.8, 1 H, HꢀC(12)); 9.78 (t, J¼1.8, HꢀC(1)).
13C-NMR (400 MHz, CDCl3): 28.1 (t, C(6)); 28.5 (t, C(7)); 29.3 (t, C(3)); 29.5 (t, C(10)); 29.7 (t, C(8));
29.7 (t, C(9)); 34.1 (t, C(11)); 36.7 (t, C(5)); 42.3 (t, C(2)); 109.9 (t, H2C¼C(4)); 114.5 (t, C(13)); 139.5 (d,
C(12)); 148.2 (s, C(4)); 202.5 (d, C(1)). EI-MS (70 eV): 179 (2, [Mꢀ29]þ ), 83 (41), 81 (55), 70 (46), 69
(66), 68 (31), 67 (61), 56 (56), 55 (100), 41 (89). Odor: aldehydic, pine, metallic.
5-(4-methylcyclohex-3-en-1-yl)-4-methylidenehexanal (26). From ethenyl 3-(4-methylcyclohex-3-en-
1-yl)-2-methylidenebutyl ether as described for 10. Yield: 93% (two isomers; 1:1). 1H-NMR (400 MHz,
CDCl3): 1.02, 1.05 (2d, J¼7.1, MeꢀC(5)); 1.09–1.23 (m, HaꢀC(6’)); 1.42–1.73 (m, HꢀC(1’), HbꢀC(6’));
1.63–1.73 (m, MeꢀC(4’)); 1.81–2.11 (m, HꢀC(5), CH2(2’), CH2(5’)); 2.23 ꢀ2.40 (m, CH2(3)); 2.57–2.63
(m, CH2(2)); 4.69–4.70, 4.71–4.72 (2m, 1 H of H2C¼C(4)); 4.79–4.81 (m, 1 H of H2C¼C(4)); 5.31–5.34,
5.35–5.38 (2m, HꢀC(3’)); 9.78–9.79 (m, HꢀC(1)). 13C-NMR (400 MHz, CDCl3): 17.5, 17.6 (2q,
MeꢀC(5)); 23.7 (q, MeꢀC(4)); 25.8, 26.0 (2t, C(3)); 26.4 (t, C(2’)); 29.6, 30.8 (2t, C(6’)); 31.0, 31.2 (2t,
C(5’)); 37.2 (d, C(5)); 42.3 (t, C(2)); 45.8, 46.5 (d, C(1’)); 109.4 (t, H2C¼C(4)); 120.9, 121.1 (2d, C(3’));
134.1, 134.4 (2s, C(4’)); 152.0, 152.3 (2s, C(4)); 202.5 (d, C(1)). EI-MS (70 eV): isomers A and B: 206 (1,
Mþ ), 95 (46), 94 (100), 93 (18), 79 (45), 77 (12), 67 (33), 55 (20), 53 (10), 41 (15). Odor: aldehydic,
green, fatty, slightly orris.
3-Methyl-3-(4-methylcyclohex-1-en-1-yl)butanal (27). From 3-methyl-3-(4-methylcyclohex-1-en-1-
yl)butanal as described for 10. Yield: 83%. 1H-NMR (400 MHz, CDCl3): 0.93 (d, J¼6.3, MeꢀC(4’)); 1.15
(s, MeꢀC(3)); 1.13–1.23 (m, HaꢀC(5’)); 1.16 (s, MeꢀC(3)); 1.54–1.77 (m, HaꢀC(3’), HꢀC(4’), HbꢀC(5));
1.96–2.16 (m, HbꢀC(3’), CH2(6’)); 2.32 (dd, J¼3.3, 14.9, HaꢀC(2)); 2.37 (dd, J¼3.0, 14.9, HbꢀC(2));
5.49–5.52 (m, HꢀC(2’)); 9.60 (dd, J¼3.0, 3.3, HꢀC(1)). 13C-NMR (400 MHz, CDCl3): 22.0 (q, C(4’));
25.0 (t, C(6’)); 28.0 (q, MeꢀC(3)); 28.1 (q, MeꢀC(3)); 28.6 (d, C(4’)); 31.8 (t, C(5’)); 34.4 (t, C(3’)); 38.0 (s,
C(3)); 53.6 (t, C(2)); 120.8 (d, C(2’)); 141.9 (s, C(1’)); 204.1 (d, C(1)). EI-MS (70 eV): 180 (14, Mþ ), 138
(40), 121 (40), 95 (100), 93 (36), 81 (70), 79 (30), 67 (31), 55 (31), 44 (33). Odor: green, aldehydic, fatty,
floral.
4,5,7,7-Tetramethyloctanal (28). Compound 10 12.0 g, 66 mmol) was dissolved in EtOH (60 ml), and
Pd/C (100 mg, 5% loading) was added. The soln. was stirred for 24 h under H2 at r.t. and ambient
pressure. The soln. was filtered, and the solvent was evaporated under reduced pressure. The crude
product was subjected to bulb-to-bulb distillation (1208/0.1 mbar) to yield 11.3 g of a colorless liquid
1
(yield: 96%; two isomers; ratio 3 :2). H-NMR (400 MHz, CDCl3): 0.80 (d, J¼6.8, MeꢀC(4)); 0.83 (d,

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CHEMISTRY & BIODIVERSITY – Vol. 11 (2014)
J¼6.8, MeꢀC(5)); 0.88 (s, Me3C(7)); 0.94–1.00 (m, HaꢀC(6)); 1.24 (dd, J¼7.1, 13.9, HbꢀC(6)); 1.31–1.55
(m, HaꢀC(3), HꢀC(4), HꢀC(5)); 1.64–1.71 (m, HbꢀC(3)); 2.37–2.47 (m, CH2(2)); 9.77–9.78 (m,
HꢀC(1)). 13C-NMR (400 MHz, CDCl3): 14.5, 16.0 (2q, MeꢀC(5)); 17.0, 19.1 (2q, Cꢀ4ꢀMe), 25.1, 26.7 (2t,
C(3)); 29.9, 30.0 (2q, Me3C(7)); 30.9, 31.1 (2s, C(7)); 32.7 33.6 (2d, C(5)); 39.1 39.3 (2d, C(4)); 42.4, 42.5
(2t, C(2)); 47.5, 49.1 (2t, C(6)); 202.9, 203.0 (2d, C(1)). EI-MS (70 eV) isomers A and B: 128 (15), 109 (7),
95 (17), 85 (17), 84 (20), 69 (10), 57 (100), 55 (15), 43 (17), 41 (30). Odor: aldehydic, green, fatty,
resinous, slightly metallic.
(4Z)-4-Ethylidene-5,7,7-trimethyloctanal (29). From 6-(ethenyloxy)-2,2,4-trimethyl-5-methylidene-
heptane as described for 10. Yield: 50% (two isomers; ratio 3 :2). Isomer A: 1H-NMR (400 MHz,
CDCl3): 0.90 (s, Me3C(7)); 1.00 (d, J¼7.1, MeꢀC(5)); 1.20 (dd, J¼5.1, 14.2, HaꢀC(6)); 1.48 (dd, J¼7.3,
14.2, HbꢀC(6)); 1.66 (dt, 6.5, 1.5, HꢀC(2’)); 2.85 (ddq, J¼5.1, 5.6, 7.1, HꢀC(5)); 5.09 (tq, J¼6.6, 1.5,
HꢀC(1’)); 9.78 (t, J¼1.8, HꢀC(1)). 13C-NMR (400 MHz, CDCl3): 13.5 (q, C(2’)); 22.4 (q, C(5)); 23.7 (t,
C(3)); 30.3 (q, Me3C(7)); 30.4 (d, C(5)); 30.6 (s, C(7)); 43.1 (t, C(2)); 48.8 (t, C(6)); 117.0 (d, C(1’)); 144.2
(s, C(4)); 203.2 (d, C(1)). EI-MS (70 eV): 196 (2, Mþ ), 122 (30), 107 (29), 97 (32), 83 (31), 81 (30), 57
1
(100), 55 (87), 43 (42), 41 (59). Isomer B: H-NMR (400 MHz, CDCl3): 0.89 (s, Me3C(7)); 1.01 (d, J¼
6.8, MeꢀC(5)); 1.14 (dd, J¼5.6, 14.2, HaꢀC(6)); 1.43 (dd, J¼6.1, 14.2, HbꢀC(6)); 1.59 (d, J¼6.8, Me(2’));
2.17–2.59 (m, HꢀC(5)); 5.32 (q, J¼6.8, HꢀC(1’)); 9.80 (t, J¼1.8, HꢀC(1)). 13C-NMR (400 MHz,
CDCl3):13.7 (q, C(2’)); 21.5 (t, C(3)); 23.5 (q, MeꢀC(5)); 30.3 (q, Me3C(7)); 30.9 (d, C(5)); 31.6 (s, C(7));
44.1 (t, C(2)); 50.6 (t, C(6)); 119.2 (d, C(1’)); 145.0 (s, C(4)); 202.6 (d, C(1)). EI-MS (70 eV): 196 (3, Mþ ),
122 (33), 107 (31), 97 (34), 83 (31), 81 (31), 57 (100), 55 (86), 43 (41), 41 (57). Odor: aldehydic, green,
fatty, resinous, slightly floral.
(4Z)-5,7,7-Trimethyl-4-propylideneoctanal (30). From 6-(ethenyloxy)-2,2,4-trimethyl-5-methylide-
1
neoctane as described for 10. Yield: 60% (two isomers; ratio 1:1). H-NMR (400 MHz, CDCl3): 0.88,
0.89 (2s, Me3C(7)); 0.95, 0.96 (2t, J¼7.6, Me(3’)); 1.00, 1.01 (2d, J¼7.1, and J¼6.8, resp., MeꢀC(5)); 1.14,
1.18 (2dd, J¼5.6, 14.2, and J¼5.1, 14.2, resp., HaꢀC(6)); 1.43, 1.45 (2dd, J ¼ 6.1, 14.2, and J¼7.1, 14.2,
resp., HbꢀC(6)); 1.94–2.59 (m, CH2(2), CH2(3), CH2(2’), HꢀC(5) (one isomer)); 2.81 (dq, J¼5.1, 7.1,
HꢀC(5) (one isomer)); 4.91, 5.19 (tq, J¼7.6, 1.5, and t, J¼7.6, HꢀC(1’)); 9.77–9.79 (m, HꢀC(1)).
13C-NMR (400 MHz, CDCl3): 14.2, 14.4 (2q, C(3’)); 20.8, 21.0 (2t, C(2’)); 21.4, 22.9 (2t, C(3)); 22.4, 23.3
(2q, MeꢀC(5)); 29.9, 30.0 (2q, Me3C(7)); 30.9 (s, C(7)); 31.2, 31.3 (2d, C(5)); 42.7, 44.2 (2t, C(2)); 48.5,
49.8 (2t, C(6)); 124.9, 126.9 (2d, C(2’)); 142.4, 143.0 (2s, C(4)); 202.1, 202.7 (2d, C(1)). EI-MS (70 eV):
isomers A and B: 210 (1, Mþ ), 192 (4, [Mꢀ18]þ ), 154 (4), 136 (15), 121 (17), 107 (15), 95 (35), 69 (33),
57 (100), 55 (55). Odor: weak, Watery, aldehydic, green, sappy.
5,7,7-Trimethyl-2,4-dimethylideneoctanal (31). From 28 as described for 7. Yield: 69%. 1H-NMR
(400 MHz, CDCl3): 0.91 (s, Me3C(7)); 1.17 (dd, J¼5.8, 14.2, HaꢀC(6)); 1.54 (dd, J¼5.3, 14.2, HbꢀC(6));
2.21–2.29 (m, HꢀC(5)); 2.96 (d, J¼17.2, HaꢀC(3)); 3.01 (d, J¼17.2, HbꢀC(3)); 4.58–4.60 (m, 1 H of
CH2¼C(4)); 4.90 (br. s, 1 H of H2C¼C(4)); 6.14 (br. s, 1 H of CH2¼C(2)); 6.30–6.31 (m, 1 H of
H2C¼C(2)); 9.61 (s, HꢀC(1)). 13C-NMR (400 MHz, CDCl3): 23.1 (q, MeꢀC(5)); 30.4 (q, Me3C(7)); 31.7
(s, C(7)); 32.2 (t, C(3)); 37.1 (d, C(5)); 110.3 (t, CH2¼C(4)); 135.9 (t, CH2¼C(2)); 148.8 (s, C(2)); 153.3 (s,
C(4)); 194.4 (s, C(1)). EI-MS (70 eV): 179 (2, Mþ ), 138 (29), 123 (100), 120 (23), 109 (32), 95 (46), 67
(25), 57 (68), 43 (26), 41 (36). Odor: green, woody, Koavone, Orivone, floral.
2,5,7,7-Tetramethyl-4-methylideneoctanal (32). Compound 31 (5.5 g, 28 mmol) was dissolved in
EtOH (60 ml), and Lindlar catalyst (200 mg, 5% Pd on CaCO3) was added. The soln. was stirred for 2 h
under H2 at r.t. and ambient pressure. The soln. was filtered, and the solvent was evaporated under
reduced pressure. The crude product was subjected to bulb-to-bulb distillation (1208/0.1 mbar) to yield
4.8 g of a colorless liquid (purity: 97% of two isomers; ratio 1:1; yield: 96%). 1H-NMR (400 MHz,
CDCl3): 0.91 (s, Me3C(7)); 1.07 (d, J¼6.8, MeꢀC(5)); 1.11, 1.13 (2d, J¼7.1, MeꢀC(2)); 1.17, 1.18 (2dd, J¼
5.8, 14.2, HaꢀC(6)); 1.49, 1.50 (dd, J¼5.3, 14.2, and J¼5.6, 14.2, resp., HbꢀC(6)); 2.00 (2 br. d, J¼15.7,
HaꢀC(3)); 2.18–2.28 (m, HꢀC(5)); 2.48, 2.50 (2br. d, J¼15.7, HbꢀC(3)); 2.59–2.66 (m, HꢀC(2)); 4.68–
4.70 (m, 1 H of CH2¼C(4)); 4.91 (br. s, 1 H of CH2¼C(4)); 9.64, 9.66 (2d, J¼2.3, and J¼2.0, HꢀC(1)).
13C-NMR (400 MHz, CDCl3): 14.1, 14.3 (2q, MeꢀC(2)); 23.2, 23.4 (2q, MeꢀC(5)); 30.4 (q, Me3C(7)); 31.6
(s, C(7)); 35.2, 35.3 (2t, C(3)); 36.9, 37.1 (2d, C(5)); 44.7, 44.8 (2d, C(2)); 49.9, 50.3 (2t, C(6)); 109.7 (t,
CH2¼C(4)); 153.2 (s, C(4)); 205.3, 205.4 (2d, C(1)). EI-MS (70 eV): isomers A and B: 181 (1, [Mꢀ15]þ ),

CHEMISTRY & BIODIVERSITY – Vol. 11 (2014)
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107 (28), 97 (25), 84 (22), 83 (45), 69 (38), 57 (100), 55 (38), 43 (35), 41 (40). Odor: green, woody,
Koavone, Orivone, floral, agrestic, minty, straw.
7-Methyl-4-methylideneoctanal (35). Chloro(pentamethylcyclopentadienyl)(cyclooctadiene)ruthe-
nium(II) (0.4 g, 1 mmol) was added to prop-2-en-1-ol (34; 4.5 g, 78 mmol). The mixture was cooled to
108, and 5-methylhex-1-yne (33; 2.0 g, 21 mmol) was added during 1 h. Stirring was continued for further
16 h at r.t. Compound 34 was evaporated under reduced pressure. The crude product was subjected to
bulb-to-bulb distillation (1308/0.1 mbar) to yield 2.4 g of a light yellow liquid (purity: 85%; yield: 84%;
1
contains 15% 8-methylnon-4-enal). H-NMR (400 MHz, CDCl3): 0.90 (d, J¼7.1, Me2C(7)); 1.29–1.35
(m, CH2(6)); 1.49–1.59 (m, HꢀC(7)); 2.01–2.05 (m, CH2(5)); 2.36 (br. t, J¼7.3, CH2(3)); 2.58 (dt, J¼1.8,
7.3, CH2(2)); 4.70 (br. s, 1 H of CH2¼C(4)); 4.78 (br. s, 1 H of CH2¼C(4)); 9.78 (t, J¼1.8, HꢀC(1)).
13C-NMR (400 MHz, CDCl3): 22.5 (q, Me2C(7)); 27.8 (d, C(7)); 28.1 (t, C(3)); 34.1 (t, C(5)); 37.0 (t,
C(6)); 41.9 (t, C(2)); 109.3 (t, H2C¼C(4)); 148.1 (s, C(4)); 202.2 (d, C(1)). EI-MS (70 eV): 139 (2, [Mꢀ
15]þ ), 83 (25), 70 (41), 69 (52), 57 (43), 56 (100), 55 (67), 43 (31), 41 (72), 39 (26).
Data of 8-Methylnon-4-enal. 1H-NMR (400 MHz, CDCl3): 0.87 (d, J¼6.8, Me2C(8)); 1.20 ꢀ1.24 (m,
HaꢀC(7)); 1.30–1.34 (m, HbꢀC(7)); 1.49–1.59 (m, HꢀC(8)); 1.95–2.00 (m, HꢀC(6)); 2.30–2.35 (m,
CH2(3)); 2.48 (dt, J¼1.8, 7.1, CH2(2)); 5.37–5.51 (m, HꢀC(5)); 5.97–6.06 (m, HꢀC(4)); 9.76 (t, J¼1.8,
HꢀC(1)). 13C-NMR (400 MHz, CDCl3): 22.4 (q, Me2C(8)); 25.2 (t, C(3)); 27.5 (d, C(8)); 30.3 (t, C(6));
38.6 (t, C(7)); 43.5 (t, C(2)); 127.0 (d, C(4)); 132.2 (d, C(5)); 202.4 (d, C(1)). EI-MS (70 eV): 136 (7, [Mꢀ
18]þ ), 84 (58), 83 (36), 69 (43), 67 (44), 56 (66), 55 (75), 43 (43), 41 (100), 39 (22). Odor: green,
resinous, fir, citrus, orange, parsley leaf, pineapple.
7-Methyl-2,4-dimethylideneoctanal (36). From 7-methyl-4-methylideneoctanal as described for 7.
1
Yield: 46% (contains 15% 8-methyl-2-methylidenenon-4-enal). H-NMR (400 MHz, CDCl3): 0.90 (d,
J¼6.51, Me2C(7)); 1.30–1.36 (m, CH2(6)); 1.50–1.59 (m, HꢀC(7)); 2.00 (br. dd, J¼7.6 8.6, CH2(5)); 3.00
(br. s, CH2(3)); 4.73 (br. s, 1 H of CH2¼C(4)); 4.87 (br. s, 1 H of CH2¼C(4)); 6.12 (br. s, 1 H of
CH2¼C(2)); 6.29 (br. s, 1 H of CH2¼C(2)); 8.59 (s, HꢀC(1)).13C-NMR (400 MHz, CDCl3): 22.9 (q,
Me2C(7)); 28.2 (d, C(7)); 34.1 (t, C(5)); 34.6 (t, C(6)); 37.3 (t, C(3)); 111.9 (t, CH2¼C(4)); 135.5 (t,
CH2¼C(2)); 147.0 (s, C(2)); 148.5 (s, C(4)); 194.5 (d, C(1)). EI-MS (70 eV): 166 (2, Mþ ), 109 (64), 97
(31), 95 (100), 81 (47), 79 (33), 67 (49), 55 (44), 41 (64), 39 (34).
1
Data of 8-Methyl-2-methylenenon-4-enal. H-NMR (400 MHz, CDCl3): 0.89 (d, J¼6.8, Me2C(7));
1.24–1.28 (m, HaꢀC(7)); 1.31–1.35 (m, HbꢀC(7)); 1.50–1.59 (m, HꢀC(8)); 2.02–2.06 (m, CH2(3)); 5.38–
5.55 (m, 2 H, C(4), C(5)); 6.03 (br. s, 1 H of CH2¼C(2)); 6.26 (br. s, 1 H of CH2¼C(2)); 9.59 (s, C(1)).
13C-NMR (400 MHz, CDCl3): 22.9 (q, Me2C(8)); 27.9 (d, C(8)); 30.8 (t, C(6)); 31.2 (t, C(3)); 39.0 (t,
C(7)); 125.5 (d, C(4)); 134.3 (d, C(5)); 136.6 (t, H2C¼C(2)); 148.5 (s, C(2)); 194.6 (d, C(1)). EI-MS
(70 eV): 166 (2, Mþ ), 109 (17), 96 (26), 95 (100), 81 (26), 79 (31), 67 (47), 55 (38), 43 (22), 41 (47).
Odor: fruity, aldehydic, green.
7-Methyl-2,4-dimethylideneoctan-1-ol (37). From 36 as described for 8. Yield: 85% (contains 15% 8-
methyl-2-methylidenenon-4-en-1-ol). 1H-NMR (400 MHz, CDCl3): 0.90 (d, Me2C(7)); 1.31–1.36 (m,
CH2(6)); 1.51–1.60 (m, CH2(6)); 1.51–1.60 (m, HꢀC(7)); 2.01 (br. dd, J¼7.6, 8.3, CH2(5)); 2.83 (br. s,
HꢀC(3)); 4.06–4.08 (m, 2 H, HꢀC(1)); 4.80–4.81 (m, 1 H of CH2¼C(4)); 4.83–4.85 (m, 1 H of
CH2¼C(4)); 4.94–4.96 (m, 1 H of CH2¼C(2)); 5.13–5.14 (m, 1 H of CH2¼C(2)). 13C-NMR (400 MHz,
CDCl3): 23.0 (q, Me2C(7)); 28.2 (d, C(7)); 33.5 (t, C(5)); 37.2 (t, C(6)); 41.2 (t, C(3)); 65.8 (t, C(1)); 111.4
(t, CH2¼C(4)); 111.9 (t, H2C¼C(2)); 146.9 (s, C(2)); 147.9 (s, C(4)). EI-MS (70 eV): 168 (0.1, Mþ ), 107
(32), 97 (63), 93 (38), 79 (100), 55 (47), 43 (43), 41 (65), 29 (23).
Data of 8-Methyl-2-methylenenon-4-en-1-ol. 1H-NMR (400 MHz, CDCl3): 0.90 (d, J¼6.6, 6 H,
Me2C(8)); 1.24–1.29 (m, HaꢀC(7)); 1.31–1.35 (m, HbꢀC(7)); 1.51 1.60 (m, HꢀC(8)); 2.02–2.06 (m,
CH2(6)); 2.78 (br. s, CH2(3)); 4.08–4.10 (m, CH2(1)); 4.90–4.92 (m, 1 H of CH2¼C(2)); 5.04–5.06 (m,
1 H of CH2¼C(2)); 5.39–5.54 (m, HꢀC(4), HꢀC(5)). 13C-NMR (400 MHz, CDCl3): 22.9 (q, Me2C(8));
27.9 (d, C(8)); 30.8 (t, C(6)); 36.9 (t, C(3)); 39.1 (t, C(7)); 66.1 (t, C(1)); 110.3 (t, H2C¼C(2)); 127.1 (d,
C(4)); 133.5 (d, C(5)); 148.6 (s, C(2)). EI-MS (70 eV): 150 (5, [Mꢀ18]þ ), 135 (14), 107 (20), 95 (40), 79
(100), 69 (30), 67 (32), 55 (53), 43 (44), 41 (70).
Ethenyl 7-Methyl-2,4-dimethylideneoctyl Ether (38). Compound 37 (2.0 g, 12 mmol), 4,7-diphenyl-
1,10-phenanthroline (0.02 g, 0.06 mmol), (CF3CO2)2 Pd (0.02 g, 0.06 mmol), and Et3N (0.05 g,
0.048 mmol) were dissolved in butyl ethenyl ether (23.8 g, 238 mmol).The mixture was stirred at 708

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for 6 h, cooled to r.t. and filtered. The vinyl ether was evaporated, and the crude product was purified via
CC to yield 1.8 g (9 mmol) of a colorless liquid (yield: 75%; contains 15% ethenyl (4E)-8-methyl-2-
methylidenenon-4-en-1-yl ether). 1H-NMR (400 MHz, CDCl3): 0.91 (d, J¼6.8, Me2C(7)); 1.30–1.36 (m,
CH2(6)); 1.51–1.61 (m, 1 H, Hꢀ7), 2.02 (br. dd, J¼7.3, 8.3, CH2(5)); 2.83 (br. s, CH2(3)); 4.04 (dd, J¼1.8,
6.8, HaꢀC(2’)); 4.15 (br. s, CH2(1)); 4.25 (dd, J¼1.8, 14.4, HbꢀC(2’)); 4.80–4.82 (m, 1 H of CH2¼C(4));
4.85–4.86 (m, 1 H of CH2¼C(4)); 5.02–5.03 (m, 1 H of CH2¼C(2)); 5.16–5.18 (m, 1 H of CH2¼C(2));
6.47 (dd, J¼6.8, 14.4, HꢀC(1’)). 13C-NMR (400 MHz, CDCl3): 23.0 (q, Me2C(7)); 28.2 (d, C(7)); 33.6 (t,
C(6)); 37.4 (t, C(3)); 70.7 (t, C(1)); 87.5 (t, C(2’)); 111.7 (t, H2C¼C(4)); 114.3 (t, H2C¼C(2)); 142.9 (s,
C(2)); 147.4 (s, C(4)); 152.0 (d, C(1’)). EI-MS (70 eV): 166 (31, [Mꢀ28]þ ), 109 (36), 95 (100), 93 (39),
81 (62), 79 (62), 67 (51), 55 (45), 43 (45), 41 (58).
1
Data of Ethenyl 8-Methyl-2-methylidenenon-4-en-1-yl Ether. H-NMR (400 MHz, CDCl3): 0.90 (d,
J¼6.8, Me2C(8)); 1.24–1.35 (m, CH2(7)); 1.51–1.61 (m, HꢀC(8)); 2.03–2.07 (m, CH2(3)); 2.79 (br. s,
CH2(3)); 4.04 (dd, J¼1.8, 6.5, HaꢀC(2’)); 4.17 (br. s, CH2(1)); 4.25 (dd, J¼1.8, 14.1, HaꢀC(2’)); 4.98 4.99
(m, 1 H of CH2¼C(2)); 5.07–5.09 (m, 1 H of CH2¼C(2)); 5.39 ꢀ5.54 (m, HꢀC(4), HꢀC(5)); 6.47 (dd, J¼
6.5, 14.1, HꢀC(1’)). 13C-NMR (400 MHz, CDCl3): 22.9 (q, Me2C(8)); 27.9 (d, C(8)); 30.6 (t, C(6)); 36.9 (t,
C(3)); 39.0 (t, C(7)); 71.2 (t, C(1)); 87.5 (t, C(2’)); 112.8 (t, CH2¼C(2)); 126.7 (d, C(4)); 133.7 (d, C(5));
144,5 C(2)); 152.0 (d, C(1’)). EI-MS (70 eV): 107 (23), 96 (72), 95 (94), 93 (49), 81 (74), 79 (100), 67
(65), 55 (59), 43 (57), 41 (84).
9-Methyl-4,6-dimethylidenedecanal (39). From compound 38 as described for 10. Yield: 59%
1
(contains 11% (6E)-10-methyl-4-methylideneundec-6-enal). H-NMR (400 MHz, CDCl3): 0.90 (d, J¼
6.6, Me2C(9)); 1.29–1.35 (m, CH2(8)); 1.50–1.60 (m, HꢀC(9)); 1.98 br. t, J¼7.3, CH2(7)); 2.34 (br. t, J¼
7.3, CH2(3)); 2.59 (dt, J¼1.8, 7.3, CH2(2)); 2.79 (br. s, CH2(5)); 4.77–4.79 (m, 1 H of CH2¼C(6)); 4.82
4.84 (m, 1 H of CH2¼C(6), 1 H of CH2¼C(4)); 4.86–4.88 (m, 1 H of CH2¼C(4)); 9.78 (t, J¼1.8, HꢀC(1)).
13C-NMR (400 MHz, CDCl3): 23.0 (q, Me2(9)); 27.8 (t, C(3)); 28.2 (d, C(9)); 33.4 (t, C(7)); 37.4 (t, C(8));
42.2 (t, C(2)); 44.6 (t, C(5)); 111.7 (t, CH2¼C(6)); 112.5 (t, CH2¼C(4)); 145.7 (s, C(4)); 147.7 (s, C96));
202.5 (d, C(1)). EI-MS (70 eV): 194 (0.1, Mþ ), 123 (36), 109 (91), 96 (100), 95 (71), 81 (72), 79 (56), 67
(40), 55 (43), 41 (53).
Data of 10-Methyl-4-methylideneundec-6-enal. 1H-NMR (400 MHz, CDCl3): 0.89 (d, J¼6.6,
Me2C(10)); 1.23–1.34 (m, CH2(9)); 1.50–1.60 (m, HꢀC(10)); 2.00–2.06 (m, CH2(8)); 2.34–2.35 (m,
CH2(3)); 2.56–2.60 (m, CH2(2)); 2.73 (br. s, CH2(5)); 4.74–4.75 (m, 1 H of H2C¼C(4)); 4.83–4.85 (m,
1 H of CH2¼C(4)); 5.36–5.52 (m, HꢀC(6), HꢀC(7)); 9.79 (t, J¼1.8, HꢀC(1)). 13C-NMR (400 MHz,
CDCl3): 22.9 (q, Me2C(10)); 27.9 (d, C(10)); 28.3 (t, C(3)); 30.8 (t, C(8)); 39.1 (t, C(9)); 40.3 (t, C(5)); 42.2
(t, C(2)); 111.7 (t, CH2¼C(4)); 127.3 (d, C(6)); 133.5 (d, C(7)); 147.4 (s, C(4)); 201.3 (d, C(1)). EI-MS
(70 eV): 194 (0.2, Mþ ), 150 (17), 133 (15), 119 (16), 109 (55), 95 (78), 81(95), 79 (82), 55 (78), 41 (100).
Odor: aldehydic, fatty, straw like, metallic.
3,6-Dimethyl-4-methylideneheptanal (40). From 4-methylpent-1-yne and but-2-en-1-ol as described
for 35. Yield: 80% (contains 15% 3,7-dimethyloct-4-enal). 1H-NMR (400 MHz, CDCl3): 0.90 (d, J¼6.6,
MeꢀC(6)); 0.91 (d, J¼6.6, MeꢀC(6)); 1.11 (d, J¼6.8, MeꢀC(3)); 1.75–1.85 (m, HꢀC(6)); 1.85–1.99 (m,
CH2(5)); 2.39 (ddd, J¼2.3, 7.1, 16.2, HaꢀC(2)); 2.59 (ddd, J¼2.3, 6.6, 16.2, HbꢀC(2)); 2.62–2.78 (m,
HꢀC(3)); 4.71 (dt, J¼1.3, 1.3, 1 H of CH2¼C(4)); 4.83 (br. s, 1 H of CH2¼C(4)); 9.73 (t, J¼2.3, HꢀC(1)).
13C-NMR (400 MHz, CDCl3): 20.5 (q, MeꢀC(3)); 22.9 (q, MeꢀC(6)); 23.0 (q, MeꢀC(6)); 26.6 (d, C(6));
34.0 (d, C(3)); 45.0 (t, C(5)); 49.8 (t, C(2)); 110.2 (t, H2C¼C(3)); 152.0 (s, C(3)); 202.0 (d, C(1)). EI-MS
(70 eV): 154 (0.8, Mþ ), 136 (2, [Mꢀ18]þ ), 112 (33, [Mꢀ42]þ ), 111 (28), 110 (29), 83 (74), 70 (73), 69
(78), 55 (76), 41 (100).
Data of 3,7-Dimethyloct-4-enal. 1H-NMR (400 MHz, CDCl3): 0.87 (d, J¼6.6, MeꢀC(7)); 0.87 (d, J¼
6.6, MeꢀC(7)); 1.08 (d, J¼6.8, MeꢀC(3)); 1.54–1.56 (m, HꢀC(7)); 5.35 (dd, J¼7.1, 15.4, HꢀC(4)); 5.45
(dd, J¼7.1, 15.4, HꢀC(5)); 9.74 (t, J¼3.0, HꢀC(1)). 13C-NMR (400 MHz, CDCl3): 20.3 (q, MeꢀC(3));
22.6 (q, MeꢀC(7)); 22.6 (q, MeꢀC(7)); 26.6 (d, C(7)); 32.1 (d, C(3)); 40.8 (t, C(6)); 50.9 (t, C(2)); 129.0
(d, C(5)); 135.4 (d, C(4)); 203.0 (d, C(1)). EI-MS (70 eV): 154 (1, Mþ ), 139 (10), 111 (20), 98 (47), 97
(55), 83 (24), 69 (62), 55 (99), 43 (56), 41 (100). Odor: aldehydic, citrus, sweaty, fruity, swimming pool.
3,6-Dimethyl-2,4-dimethylideneheptanal (41). From 40 as described for 7. Yield: 56% (contains 14%
3,7-dimethyl-2-methylideneoct-4-enal). 1H-NMR (400 MHz, CDCl3): 0.87 (d, J¼6.3, MeꢀC(6)); 0.88 (d,
J¼6.3, MeꢀC(6)); 1.18 (d, J¼7.1, MeꢀC(3)); 1.75–1.91 (m, CH2(5), HꢀC(6)); 3.35 (br. q, J¼7.1,

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HꢀC(3)); 4.87 (br. s, CH2¼C(4)); 6.06 (s, 1 H of CH2¼C(2)); 6.27 (s, 1 H of CH2¼C(2)); 9.58 (s, HꢀC(1)).
13C-NMR (400 MHz, CDCl3): 19.2 (q, MeꢀC(3)); 22.6 (q, Me2C(6)); 26.5 (d, C(6)); 36.4 (d, C(3)); 45.8 (t,
C(5)); 111.2 (t, CH2¼C(4)); 134.0 (t, CH2¼C(2)); 150.6 (s, C(2)); 154.0 (s, C(4)); 194.4 (d, C(1)). EI-MS
(70 eV): 166 (0.8, Mþ ), 151 (9, [Mꢀ15]þ ), 123 (100, [Mꢀ43]þ ), 109 (39), 95 (49), 83 (48), 67 (34), 55
(37), 43 (33), 41 (48).
Data of 3,7-Dimethyl-2-methylideneoct-4-enal. 1H-NMR (400 MHz, CDCl3): 1.17 (d, J¼7.1,
MeꢀC(3)); 1.55–1.66 (m, HꢀC(7)); 3.38 (dq, J¼6.3, 7.1, HꢀC(3)); 5.38–5.51 (m, HꢀC(4), HꢀC(5));
5.99 (s, 1 H of CH2¼C(2)); 6.24 (s, 1 H of CH2¼C(2)); 9.55 (s, HꢀC(1)). 13C-NMR (400 MHz, CDCl3):
19.6 (q, MeꢀC(3)); 22.6 (q, Me2C(7)); 28.8 (d, C(7)); 34.7 (d, C(3)); 42.3 (t, C(6)); 129.6 (d, C(5)); 133.4
(t, CH2¼C(2)); 133.6 (d, C(4)); 150.6 (s, C(2)); 194.4 (d, C(1)). EI-MS (70 eV): 151 (2, [Mꢀ15]þ ), 123
(9, [Mꢀ43]þ ), 109 (100), 95 (26), 81 (41), 79 (20), 67 (28), 55 (29), 43 (20), 41 (34). Odor: minty,
agrestic, aldehydic, green, metallic.
3,7-Dimethyl-4-methylideneoctanal (42). From 33 and but-2-en-1-ol as described for 35. Yield: 86%
(contains 13% 3,8-dimethylnon-4-enal). 1H-NMR (400 MHz, CDCl3): 0.92 (d, J¼6.6, Me2C(7)); 1.11 (d,
J¼7.1, MeꢀC(3)); 1.31–1.37 (m, CH2(6)); 1.51–1.62 (m, HꢀC(7)); 2.02–2.06 (m, CH2(5)); 2.39 (ddd, J¼
2.3, 7.8, 16.4, HaꢀC(2)); 2.58 (ddd, J¼2.3, 6.6, 16.4, HbꢀC(2)); 2.69–2.77 (m, HꢀC(3)); 4.78 (br. s, 1 H of
CH2¼C(4)); 4.80 (br. s, 1 H of CH2¼C(4)); 9.72 (dd, J¼2.3, 2.3, HꢀC(1)). 13C-NMR (400 MHz, CDCl3):
20.6 (q, MeꢀC(3)); 22.9 (q, Me2C(7)); 28.3 (d, C(7)); 32.6 (t, C(5)); 34.6 (d, C(3)); 37.7 (t, C(6)); 49.8 (t,
C(2)); 108.0 (t, H2C¼C(4)); 153.6 (s, C(4)); 202.9 (d, C(9)). EI-MS (70 eV): 168 (0.8, Mþ ), 126 (11, [Mꢀ
42]þ ), 111 (17), 109 (15), 107 (17), 83 (48), 70 (100), 69 (56), 55 (92), 41 (86).
Data of 3,8-Dimethylnon-4-enal. 1H-NMR (400 MHz, CDCl3; selected signals): 0.88 (d, J¼6.6,
Me2C(8)); 1.07 (d, J¼6.6, MeꢀC(3)); 1.20–1.26 (m, CH2(7)); 1.50–1.57 (m, HꢀC(8)); 5.33–5.49 (m,
HꢀC(4), HꢀC(5)); 9.73 (dd, J¼2.3, 2.3, HꢀC(1)). 13C-NMR (400 MHz, CDCl3): 21.1 (q, MeꢀC(3)); 23.0
(q, Me2C(8)); 27.9 (d, C(8)); 30.7 (t, C(6)); 32.0 (d, C(3)); 37.7 (t, C(7)); 50.9 (t, C(2)); 130.5 (d, C(5));
134.0 (d, C(4)); 203.2 (d, C(1)). EI-MS (70 eV): 168 (0.6, Mþ ), 124 (11), 111 (22), 109 (8), 107 (9), 97
(75), 69 (69), 55 (100), 43 (53), 41 (92). Odor: fruity, orange, metallic, sweet, floral, rubbery.
3,7-Dimethyl-2,4-dimethylideneoctanal (43). From 42 as described for 7. Yield: 57% (contains 13%
1
3,8-dimethyl-2-methylidenenon-4-enal). H-NMR (400 MHz, CDCl3): 0.88 (d, J¼6.6, MeꢀC(7)); 0.89
(d, J¼6.6, MeꢀC(7)); 1.19 (d, J¼7.1, MeꢀC(3)); 1.29–1.35 (m, CH2(6)); 1.46–1.49 (m, HꢀC(7)); 1.88–
2.05 (m, CH2(5)); 3.39 (br. q, J¼7.1, HꢀC(3)); 4.82 (br. s, 1 H of CH2¼C(4)); 4.88 (br. s, 1 H of
CH2¼C(4)); 6.06 (s, 1 H of CH2¼C(2)); 6.26 (s, 1 H of CH2¼C(2)); 9.58 (s, HꢀC(1)). 13C-NMR (400 MHz,
CDCl3):19.1 (q, MeꢀC(3)); 23.0 (q, Me2C(7)); 28.2 (d, C(7)); 33.7 (t, C(5)); 37.6 (t, C(6)); 109.1 (t,
CH2¼C(4)); 134.0 (t, CH2¼C(2)); 152.2 (s, C(4)); 154.0 (s, C(2)); 194.5 (d, C(1)). EI-MS (70 eV): 165 (5,
[Mꢀ15]þ ), 123 (100), 109 (99), 95 (68), 91 (34), 81 (55), 67 (48), 55 (62), 41 (71), 39 (39).
1
Data of 3,8-Dimethyl-2-methylidenenon-4-enal: H-NMR (400 MHz, CDCl3, selected signals): 0.88
(d, J¼6.6, MeꢀC(8)); 0.89 (d, J¼6.6, MeꢀC(8)); 1.16 (d, J¼7.1, MeꢀC(3)); 5.40–5.51 (m, HꢀC(4),
HꢀC(5)); 5.99 (s, 1 H of H2C¼C(2)); 6.24 (br. s, 1 H of H2C¼C(2)); 9.55 (s, HꢀC(1)). 13C-NMR
(400 MHz, CDCl3): 19.6 (q, MeꢀC(3)); 22.8 (q, Me2C(8)); 27.9 (d, C(8)); 30.7 (t, C(6)); 34.6 (d, C(3));
39.0 (t, C(7)); 131.0 (d, C(5)); 132.2 (d, C(4)); 133.5 (t, H2C¼C(2)); 154.8 (s, C(2)); 194.5 (d, C(1)). EI-MS
(70 eV): 165 (2, [Mꢀ15]þ ), 109 (100), 95 (23), 91 (14), 81 (52), 77 (17), 67 (25), 55 (35), 41 (42), 39
(20). Odor: green, metallic, slightly fruity, slightly floral.
5,9-Dimethyl-4,6-dimethylidenedecanal (44). From 3,7-dimethyl-4-methylidene-2-(vinyloxymethyl)-
oct-1-ene as described for 10. Yield: 48% (contains 13% 5,10-dimethyl-4-methylideneundec-6-enal).
1H-NMR (400 MHz, CDCl3): 0.89 (d, J¼6.6, MeꢀC(9)); 0.90 (d, J¼6.6, MeꢀC(9)); 1.18 (d, J¼7.1,
MeꢀC(5)); 1.29–1.35 (m, CH2(8)); 1.49–1.59 (m, HꢀC(9)); 1.87–2.00 (m, CH2(7)); 2.23–2.37 (m,
CH2(3)); 2.56–2.60 (m, CH2(2)); 2.85 (br. q, J¼7.1, HꢀC(5)); 4.81 (br. s, 1 H of CH2¼C(6)); 4.84 (br. s,
1 H of CH2¼C(6), 1 H of CH2¼C(4)); 4.93 (br. s, 1 H of CH2¼C(4)); 9.77 (t, J¼1.8, HꢀC(1)). 13C-NMR
(400 MHz, CDCl3):18.7 (q, MeꢀC(5)); 22.9 (q, MeꢀC(9)); 23.1 (q, MeꢀC(9)); 26.4 (t, C(3)); 28.3 (d,
C(9)); 32.2 (t, C(7)); 37.8 (t, C(8)); 42.5 (t, C(2)); 46.8 (d, C(5)); 109.5 (t, CH2¼C(6)); 110.2 (t,
CH2¼C(4)); 150.6 (s, C(4)); 152.5 (s, C(6)); 202.7 (d, C(1)). MS (70 eV): 165 (11), 164 (11, [Mꢀ44]þ ),
137 (52), 123 (66), 109 (70), 95 (100), 93 (80), 81 (52), 55 (51), 41 (62).
Data of 5,10-Dimethyl-4-methylideneundec-6-enal. 1H-NMR (400 MHz, CDCl3): 0.89 (d, J¼6.6,
MeꢀC(10)); 0.90 (d, J¼6.6, MeꢀC(10)); 1.14 (d, J¼6.8, MeꢀC(5)); 1.22–1.28 (m, CH2(8), CH2(9)); 2.77

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(br. dq, J¼7.1, 6.8, HꢀC(5)); 4.72–4.73 (m, 1 H of CH2¼C(4)); 4.86–4.87 (m, 1 H of CH2¼C(4)); 5.32
(dddd, J¼1.3, 1.3, 7.3, 15.2, HꢀC(6)); 5.45 (dddd, J¼0.8, 6.6, 6.6, 15.2, HꢀC(7)); 9.78 (t, J¼1.8, HꢀC(1)).
13C-NMR (400 MHz, CDCl3): 19.7 (q, MeꢀC(5)); 22.9 (q, Me2C(10)); 26.7 (279 (t, C(3)); 27.9 (d, Cꢀ10);
30.7 (t, C(8)); 39.1(t, C(9)); 43.4 (d, C(5)); 46.7 (t, C(2)); 108.9 (t, H2C¼C(4)); 130.7 (d, C(7)); 133.9 (d,
C(6)); 202.7 (d, C(1)). EI-MS (70 eV): 165 (7), 123 (22), 109 (50), 95 (76), 93 (71), 82 (100), 81 (52), 67
(49), 55 (59), 41 (64). Odor: aldehydic, metallic, mandarin, coriander.
5,8-Dimethyl-4,6-dimethylidenenonanal (45). From 3,6-dimethyl-2,4-dimethylideneheptyl ethenyl
1
ether as described for 10. Yield: 71% (contains 13% 5,9-dimethyl-4-methylidenedec-6-enal). H-NMR
(400 MHz, CDCl3): 0.88 (d, J¼6.3, MeꢀC(8)); 0.90 (d, J¼6.3, MeꢀC(8)); 1.18 (d, J¼7.1, MeꢀC(5));
1.73–1.93 (m, CH2(7), HꢀC(8)); 2.33–2.39 (m, CH2(3)); 2.59 (dd, J¼1.8, 7.6, CH2(2)); 2.81 (br. q, J¼7.1,
HꢀC(5)); 4.80 (s, 1 H of CH2¼C(6)); 4.84 (s, 1 H of CH2¼C(4)); 4.89 (s, 1 H of CH2¼C(6)); 4.93 (s, 1 H of
CH2¼C(4)); 9.77 (t, J¼1.8, HꢀC(1)). 13C-NMR (400 MHz, CDCl3):18.7 (q, MeꢀC(5)); 22.8 (q,
MeꢀC(8)); 23.2 (q, MeꢀC(8)); 26.2 (t, C(3)); 26.6 (d, C(8)); 42.5 (t, C(2)); 44.7 (t, C(7)); 46.4 (d, C(5));
110.3 (t, CH2¼C(4)); 110.9 (t, H2C¼C(6)); 150.6 (s, C(4)); 152.0 (s, C(6)); 202.7 (d, C(1)). EI-MS (70 eV):
179 (9, [Mꢀ15]þ ), 137 (95), 107 (95), 95 (100), 93 (82), 91 (56), 81 (82), 67 (54), 55 (63), 41 (87).
1
Data of 5,9-Dimethyl-4-methylidenedec-6-enal. H-NMR (400 MHz, CDCl3, selected signals): 0.88
(d, J¼6.3, MeꢀC(9)); 0.90 (d, J¼6.3, MeꢀC(9)); 1.15 (d, J¼6.8 MeꢀC(5)); 4.73–4.74 (m, 1 H of
CH2¼C(4)); 4.87–4.88 (m, 1 H of CH2¼C(4)); 5.31 (dddd, J¼1.0, 1.0, 7.6, 15.2, HꢀC(7)); 5.44 (ddd, J¼
0.75, 7.1, 7.1, HꢀC(6)); 978 (t, J¼1.8, HꢀC(1)). EI-MS (70 eV): 179 (5, [Mꢀ15]þ ), 109 (73), 107 (82), 95
(100), 93 (82), 81 (78), 79 (74), 67 (72), 55 (91), 41 (99). Odor: aldehydic, green, slightly fatty, floral.
(4E)-5-[4-(tert-Butyl)phenyl]pent-4-enal (46). By-product of the condensation of 1-(tert-butyl)-4-
ethynylbenzene with 34 as described for 35. Yield: 3%. 1H-NMR (400 MHz, CDCl3): 1.35 (s, Me3C(7’));
2.58 (ddt, J¼1.5, 6.3, 6.8, CH2(3)); 2.65 (dt, J¼1.5, 7.6, CH2(2)); 6.21 (dt, J¼15.7, 6.3, HꢀC(4)); 6.46 (br.
d, J¼15.7, HꢀC(5)); 7.32 (d, J¼8.8, HꢀC(2’), HꢀC(6’)); 7.37 (d, J¼8.8, HꢀC(3’), HꢀC(5’)); 9.85 (d, J¼
1.5, HꢀC(1)). 13C-NMR (400 MHz, CDCl3): 26.0 (t, C(3)); 31.7 (q, Me2C(7’)); 34.9 (s, C(7)); 43.8 (t,
C(2)); 125.9 (d, C(3’), C(5’)); 126.2 (d, C(2’), C(6’)); 127.8 (d, C(4)); 131.3 (d, C(5)); 134.9 (s, C(1’));
150.7 (s, C(4’)); 202. (d, C(1)). EI-MS (70 eV): 216 (14, Mþ ), 201 (100), 1445 (53), 131 (33), 129 (38),
128 (3), 117 (15), 115 (30), 91 (17), 57 (31). Odor: aldehydic, green, fatty, citrus, orange, coriander.
4-[4-(tert-Butyl)phenyl]pent-4-enal (47). From 1-(tert-butyl)-4-ethynylbenzene and 34 as described
for 35. Yield: 16%. 1H-NMR (400 MHz, CDCl3): 1.36 (s, Me3C(7’)); 2.65 (dt, J¼1.5, 7.6, CH2(2)); 2.88 br.
t, J¼7.6, CH2(3)); 5.08–5.10 (m, 1 H of CH2¼C(4)); 5.36 (br. s, 1 H of CH2¼C(4)); 7.37 (d, J¼8.8,
HꢀC(2’), HꢀC(6’)); 7.40 (d, J¼7.8, HꢀC(3’), HꢀC(5’)); 9.82 (d, J¼1.5, HꢀC(1)). 13C-NMR (400 MHz,
CDCl3): 28.0 (t, C(3)); 31.7 (q, Me3C(7’)); 34.9 (s, C(7’)); 42.9 (t, C(2)); 112.7 (t, CH2¼C(4)); 125.8 (d,
C(3’), C(5’)); 126.1 (d, C(2’), C(6’)); 137.7 (d, C(1’)); 146.7 (s, C(4)); 151.2 (s, C(4’)); 202.4 (d, C(1)). EI-
MS (70 eV): 201 (6, [Mꢀ15]þ ), 174 (40), 173 (13), 160 (28), 159 (100), 131 (32), 129 (15), 128 (18), 115
(17), 91 (13).Odor: aldehydic, green, floral, fatty, weak.
1-Ethynyl-3,3,5-trimethylcyclohexanol (49). 3,3,5-Trimethylcyclohexanone (48; 4.0 g, 29 mmol) was
added dropwise to a 0.5m EtMgBr soln. (63 ml, 32 mmol) at 58. The mixture was stirred for 3 h, and the
temp. was allowed to rise to r.t. The mixture was poured onto ice-cold, sat. NH4Cl soln. (100 ml).
tBuOMe was added (150 ml). The org. phase was washed with H2O (2ꢁ80 ml) and brine (80 ml), dried
(MgSO4), and filtered. The solvent was evaporated under reduced pressure. The crude product was
subjected to bulb-to-bulb distillation (1008/10 mbar) to yield 3.0 g (18 mmol) of a colorless liquid (purity:
78%; yield: 49%). 1H-NMR (400 MHz, CDCl3): 0.83 (dd, J¼12.6, 12.6, HaꢀC(4)), 0.91 (d, J¼5.3,
MeꢀC(5)); 0.92 (s, MeꢀC(3)); 1.10 (s, MeꢀC(3)); 1.26 (dd, J¼12.9, 13.1, HaꢀC(6)); 1.43 (dddd, J¼2.0,
2.0, 3.0, 13.1, HbꢀC(6)); 1.52 (d, J¼14.4, HaꢀC(2)); 1.79 (ddd, J¼2.3, 2.3, 14.4, HbꢀC(2)); 1.91–2.04 (m,
HbꢀC(4), HꢀC(5)). 13C-NMR (400 MHz, CDCl3): 22.5 (q, MeꢀC(5)); 23.9 (q, Me2C(3)); 27.7 (s, C(5));
31.6 (s, C(3)); 47.6 (t, C(6)); 48.2 (t, C(4)); 50.3 (t, C(2)); 68.6 (s, C(1)); 70.0 (s, C(2’)); 90.1 (s, C(1’)). EI-
MS (70 eV): 166 (2, Mþ ), 151 (21), 133 (25), 123 (18), 109 (100), 95 (85), 83 (35), 55 (31), 53 (28), 41
(29).
1-Ethynyl-3,5,5-trimethylcyclohexene (50). Compound 49 (3.0 g, 78%;13.9 mmol) was dissolved in
pyridine (30 ml) and cooled to 08. POCl3 (3.2 g, 21 mmol) was added dropwise. The mixture was stirred
for 16 h, while allowing the temp. to rise to r.t. The mixture was poured onto ice-cold 2n HCl. Hexane
(100 ml) was added. The org. layer was washed with 2n HCl (2ꢁ50 ml), sat. NaHCO3 soln. (50 ml), H2O

CHEMISTRY & BIODIVERSITY – Vol. 11 (2014)
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(2ꢁ60 ml), and brine (60 ml). The soln. was dried (MgSO4) and filtered: The solvent was evaporated
under reduced pressure. The crude product was subjected to bulb-to-bulb distillation (808/10 mbar) and
further purified via CC to afford 0.8 g (5 mmol) of a colorless liquid (yield: 39%; contains 28% 1-ethynyl-
3,3,5-trimethylcyclohex-1-ene). 1H-NMR (400 MHz, CDCl3): 0.97 (d, J¼6.6, MeꢀC(3)); 1.01 (s,
MeꢀC(5)); 1.02 (s, MeꢀC(5)); 1.07 (m, HaꢀC(4)); 1.45–1.50 (m, HbꢀC(4)); 1.72 (dd, J¼2.5, 16.2,
HaꢀC(6)); 1.75–1.85 (m, HꢀC(3)); 2.14–2.19 (m, HbꢀC(6)); 2.80 (s, HꢀC(2’)); 5.94 (m, HꢀC(2)).
13C-NMR (400 MHz, CDCl3): 22.3 (q, MeꢀC(3)); 26.1 (q, MeꢀC(5)); 28.9 (d, C(3)); 31.0 (q, MeꢀC(5));
34.1 (s, C(5)); 38.1 (t, C(6)); 45.6 (t, C(4)); 74.8 (s, C(2’)); 85.9 (s, C(1’)); 117.7 (s, C(1)); 146.3 (d, C(2)).
EI-MS (70 eV): 148 (41, Mþ ), 133 (100, [Mꢀ15]þ ), 119 (10), 117 (11), 115 (13), 106 (13), 105 (54), 91
(55), 77 (14), 41 (14).
Data of 1-Ethynyl-3,3,5-trimethylcyclohex-1-ene. 1H-NMR (400 MHz, CDCl3, selected signals): 1.70
(dd, J¼2.5, 16.4, HaꢀC(6)); 1.97–2.03 (m, HbꢀC(6)); 2.79 (s, HꢀC(2’)); 6.03–6.05 (m, HꢀC(2)).
13C-NMR (400 MHz, CDCl3): 21.4 (q, Me2C(5)); 25.5 (q, MeꢀC(3)); 29.3 (d, C(5)); 30.2 (s, C(3)); 32.0
(q, MeꢀC(3)); 42.9 (t, C(6)); 44.3 (t, C(4)); 74.6 (s, C(2’)); 86.1 (s, C(1’)); 118.4 (s, C(1)); 141.3 (d, C(2)).
EI-MS (70 eV): 148 (42, Mþ ), 133 (75, [Mꢀ15]þ ), 119 (21), 117 (11), 115 (13), 105 (47), 91 (100), 83
(21), 77 (19), 41 (16).
4-(3,5,5-Trimethylcyclohex-1-en-1-yl)pent-4-enal (51). From 50 as described for 35: Yield: 44%
(contains 23% 4-(3,3,5-trimethylcyclohex-1-en-1-yl)pent-4-enal, and 8% 5-(3,5,5-trimethylcyclohex-1-
en-1-yl)pent-4-enal, and 5-(3,3,5-trimethylcyclohex-1-en-1-yl)pent-4-enal). 1H-NMR (400 MHz,
CDCl3): 1.00–1.04 (m, MeꢀC(3’), Me2C(5’), HaꢀC(4’)); 1.46–1.51 (m, HbꢀC(4’)); 2.02 (dd, J¼2.0,
16.2, HaꢀC(6’)); 1.73–1.84 (m, HꢀC(3’)); 2.25 (br. dd, J¼4.0, 16.2, HbꢀC(6’)); 2.60–2.64 (m, CH2(2),
CH2(3)); 4.86 (s, 1 H of CH2¼C(4)); 5.05 (s, 1 H of CH2¼C(4)); 5.55 (br. s, HꢀC(2’)); 9.80 (m, HꢀC(1)).
13C-NMR (400 MHz, CDCl3): 22.8 (q, MeꢀC(3’)); 26.5 (t, C(3)); 29.3 (q, Me2C(5’)); 32.6 (d, C(3’)); 33.8
(s, C(5’)); 35.7 (t, C(6’)); 40.4 (t, C(2)); 43.5 (t, C(4’)); 110.6 (t, H2C¼C(4)); 124.8 (s, C(1’)); 130.0 (d,
C(2’)); 133.0 (s, C(4)); 202.7 (d, C(1)). EI-MS (70 eV): 206 (20, Mþ ), 191 (17, [Mꢀ15]þ ), 173 (55, [Mꢀ
33]þ ), 164 (23), 150 (53), 149 (74), 121 (85), 107 (100), 105 (72), 91 (79). Odor: aldehydic, floral, green.
4-(3,3,5,5-Tetramethylcyclohex-1-en-1-yl)pent-4-enal (54). From 1-ethynyl-3,3,5,5-tetramethylcyclo-
hex-1-ene and 34 as described for 35. Yield: 56%. 1H-NMR (400 MHz, CDCl3): 0.98 (s, Me2C(5’)); 1.05 (s,
Me2C(3’)); 1.36 (s, CH2(4’)); 1.91 (br. d, J¼1.5, CH2(6’)); 2.60–2.68 (m, 4 H, CH2(2), CH2(3)); 4.87 (br. s,
1 H of CH2¼C(4)); 5.03 (br. s, 1 H of CH2¼C(4)); 5.55–5.56 (m, HꢀC(2’)); 9.80–9.81 (m, HꢀC(1)).
13C-NMR (400 MHz, CDCl3): 26.7 (t, C(3)); 30.5 (q, MeꢀC(3’), MeꢀC(5’)); 32.0 (q, MeꢀC(3’),
MeꢀC(5’)); 33.3 (s, C(5’)); 38.5 (s, C(3’)); 40.3 (t, C(6’)); 43.5 (t, C(2)); 49.8 (t, C(4’)); 110.7 (t,
H2C¼C(4)); 132.1 (s, C(1’)); 134.0 (d, C(2’)); 147.1 (s, C(4’)); 202.7 (d, C(1)). EI-MS (70 eV): 220 (17),
177 (31), 161 (22), 137 (21), 135 (18), 121 (100), 107 (30), 105 (22), 91 (31), 41 (22). Odor: green, fruity,
nutty.
4-[(5R)-5-Methyl-2-(propan-2-yl)cyclohex-1-en-1-yl]pent-4-enal (55). From (4R)-2-ethynyl-4-
methyl-1-(propan-2-yl)cyclohexene and 34 as described for 35: Yield: 7%. 1H-NMR (400 MHz, CDCl3):
0.93 (d, J¼6.6, 6 H, MeꢀC(7’)); 0.85 (d, J¼7.1, MeꢀC(5’)); 1.11–1.20 (m, HaꢀC(4’)); 1.59–1.76 (m,
HaꢀC(3’), HbꢀC(4’), HꢀC(5’)); 1.90–2.11 (m, HbꢀC(3’), CH2(6’)); 2.43–2.55 (m, HꢀC(2), HꢀC(3));
2.78 (qq, J¼6.6, 6.6, HꢀC(7’)); 4.71 (m, 1 H of CH2¼C(4)); 4.78 (m, 1 H of CH2¼C(4)). 13C-NMR
(400 MHz, CDCl3): 21.3 (q, MeꢀC(7’)); 21.8 (q, MeꢀC(7’)); 22.1 (q, MeꢀC(5’)); 22.6 (t, C(3)); 28.6 (t,
C(3’)); 29.4 (d, C(5’)); 30.8 (d, C(7’)); 31.6 (t, C(4’)); 39.0 (t, C(6’)); 42.2 (t, C(2)); 11.8 (t, CH2¼C(4));
131.1 (s, C(1’)); 137.4 (s, C(2’)); 150.0 (s, C(4)); 202.6(d, C(1)). EI-MS (70 eV): 220 (13, Mþ ), 176 (43),
161 (100), 135 (57), 121 (77), 119 (72), 107 (91), 105 (87), 93 (71), 91(83). Odor: aldehydic, fruity, citrus.
4-(5-methyl-3-propylcyclohex-1-en-1-yl)pent-4-enal (56). From 1-ethynyl-5-methyl-3-propylcyclo-
hexene and 34 as described for 35. Yield: 3%. 1H-NMR (400 MHz, CDCl3): 0.93 (t, J¼7.1, Me(9’)); 1.03
(d, J¼6.8, MeꢀC(5’)); 1.25–1.44 (m, HꢀC(3’), HaꢀC(4’), CH2(7’), CH2(8’)); 1.55–1.84 (m, HbꢀC(4’),
HꢀC(5’), CH2(6’)); 2.62–2.63 (m, CH2(2), CH2(3)); 4.86 (br. s, 1 H of CH2¼C(4)); 5.06 (s, 1 H of
CH2¼C(4)); 5.68 (br. s, HꢀC(2’)); 9.80 (br. s, HꢀC(1)). 13C-NMR (400 MHz, CDCl3): 14.7 (q, C(9’)); 20.3
(t, C(8’)); 22.4 (q, MeꢀC(5’)); 26.5 (t, C(3)); 29.7 (d, C(5’)); 33.6 (t, C(6’)); 34.5 (d, C(3’)); 35.7 (t, C(4’));
43.4 (t, C(2)); 110.4 (t, H2C¼C(4)); 130.1 (d, C(2’)); 135.9 (s, C(1’)); 146.8 (s, C(4)); 202.7 (d, C(1)). EI-
MS (70 eV): 220 (15, Mþ ), 164 (100), 135 (49), 121 (38), 105 (61), 93 (84), 91 (88), 79 (54), 55 (73), 41
(59). Odor: aldehydic, green, fatty.

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CHEMISTRY & BIODIVERSITY – Vol. 11 (2014)
4-(5-Methyl-3-propylcyclohexa-1,5-dien-1-yl)pent-4-enal (57). From 3-ethynyl-1-methyl-5-propylcy-
1
clohexa-1,3-diene and 34 as described for 35. Yield: 5%. H-NMR (400 MHz, CDCl3): 0.93 (t, J¼7.1,
Me(9’)); 130–1.44 (m, CH2(7’), CH2(8’)); 1.65–1.8 (m, HaꢀC(4’)); 1.80 (t, J¼1.8, MeꢀC(5’)); 1.87–20.9
(m, HꢀC(3’), HbꢀC(4’)); 2.38–2.47 (m, CH2(3)); 2.65–2.66 (m, CH2(2)); 4.89 (br. s, 1 H of CH2¼C(4));
4.92 (br. s, 1 H of CH2¼C(4)); 4.99 (br. s, HꢀC(2’)); 5.21 (s, HꢀC(6’)); 9.82 (m, HꢀC(1)). 13C-NMR
(400 MHz, CDCl3): 14.7 (q, C(9’)); 20.4 (t, C(8’)); 21.9 (q, MeꢀC(5’)); 26.2 (t, C(3)); 30.9 (t, C(4’)); 34.4
(d, C(3’)); 37.0 (t, C(7’)); 43.7 (t, C(2)); 112.5 (t, H2C¼C(4)); 126.5 (d, C(6’)); 127.6 (d, C(2’)); 131.6 (s,
C(1’)); 137.9 (s, C(5’)); 144.3 (s, C(4)); 202.4 (d, C(1)). EI-MS (70 eV): 218 (11, Mþ ), 200 (1, [Mꢀ18]þ ),
176 (55, [Mꢀ42]þ ), 133 (86), 119 (39), 105 (77), 91 (100), 77 (36), 55 (34), 41 (37). Odor: green, dusty,
chocolate.
4-(4,4-Dimethylcyclohex-1-e 34 as described for 35: Yield: 35% (contains 18% (4E)-5-(4,4-
1
dimethylcyclohex-1-en-1-yl)pent-4-enal). H-NMR (400 MHz, CDCl3): 0.92 (s, Me2C(4’)); 1.42 (t, J¼
6.6, CH2(5’)); 1.92–1.95 (m, CH2(3’)); 2.16–2.20 (m, CH2(6’)); 260 (s, CH2(2), CH2(3)); 4.84 (s, 1 H of
CH2¼C(4)); 5.03 (br. s, 1 H of CH2¼C(4)); 5.78–5.82 (m, HꢀC(2’)); 9.78 (br. s, HꢀC(1)). 13C-NMR
(400 MHz, CDCl3): 23.8 (t, C(6’)); 26.0 (t, C(3)); 28.1 (q, Me2C(4)); 28.4 (s, C(4’)); 35.6 (t, C(5’)); 39.7 (t,
C(3’)); 43.1 (t, C(2’)); 109.7 (t, H2C¼C(4)); 123.8 (d, C(2’)); 134.0 (s, (C(1’)); 146.3 (s, C(4)); 202.3 (d,
C(1)). EI-MS (70 eV): 192 (6, Mþ ), 150 (70, [Mꢀ42]þ ), 107 (55), 93 (75), 92 (33), 91 (87), 79 (100), 77
(52), 41 (51), 29 (51). Odor: fatty floral.
4-(8,8-Dimethylspiro[2.5]oct-4-en-4-yl)pent-4-enal (59). From 4-ethynyl-8,8-dimethylspiro[2.5]oct-
4-ene and 34 as described for 35. Yield: 44%. 1H-NMR (400 MHz, CDCl3): 0.40 (m, HaꢀC(7’),
HaꢀC(8’)); 0.64 (m, HbꢀC(7’), HbꢀC(8’)); 0.80 (s, Me2C(5’)); 1.51 (t, J¼6.6, CH2(4’)); 2.14 (dt, J¼3.54,
6.6, CH2(3’)); 2.34 (br. t, J¼7.3, CH2(3)); 2.54 (dd, J¼1.8, 6.8, CH2(2)); 4.63–4.64 (m, 1 H of CH2¼C(4));
4.77–4.78 (m, 1 H of CH2¼C(4)); 5.34 (t, J¼3.54, HꢀC(2’)); 9.78 (t, J¼1.8, HꢀC(1)). 13C-NMR
(400 MHz, CDCl3): 7.9 (t, C(7’), C(8’)); 23.0 (t, C(3’)); 24.5 (q, Me2C(5’)); 26.2 (s, C(6’)); 31.1 (s, C(1’));
35.8 (t, C(4’)); 42.3 (t, C(2)); 113.1 (t, H2C¼C(4)); 123.5 (d, C(2’)); 142.7 (s, C(1’)); 147.5 (s, C(4)); 202.3
(d, C(1)). EI-MS (70 eV): 218 (1, Mþ ), 203 (19), 159 (41), 131 (62), 119 (59), 117 (56), 105 (80), 91
(100), 41 (48), 29 (50). Odor: straw, woody fruity, slightly Kephalis like.
1
5-Methylhex-1-yn-3-ol (61). From 3-methylbutanal (60) as described for 49. Yield: 84%. H-NMR
(400 MHz, CDCl3): 0.94 (d, J¼6.6, MeꢀC(3)); 0.96 (d, J¼6.6, MeꢀC(3)); 1.59 (ddd, J¼6.8, 6.8, 13.4,
HaꢀC(2)); 1.66 (ddd, J¼7.3, 7.3 13.4, HbꢀC(2)); 1.82–1.92 (m, HꢀC(3)); 2.47 (d, J¼2.3, HꢀC(2’)); 4.39–
4.45 (m, HꢀC(1)). 13C-NMR (400 MHz, CDCl3): 22.8 (q, MeꢀC(3)); 22.9 (q, MeꢀC(3)); 25.1 (d, C(3));
47.1 (t, C(2)); 61.1 (d, C(1)); 73.0 (d, C(2’)); 85.7 (s, C(1’)). EI-MS (70 eV): 97 (39), 79 (37), 77 (18), 70
(15), 57 (100), 56 (41), 55 (90), 41 (65), 39 (27), 29 (26).
6-Methylhepta-1,2-dien-4-ol (62). Compound 61 (10.8 g, 96 mmol) was dissolved in dioxane
i
(120 ml). Paraformaldeyde (7.2 g, 241 mmol), CuBr (6.9 g, 48 mmol), and Pr2NH (20.5 g, 202 mmol)
were added. The mixture was stirred under reflux for 1 h. The suspension was cooled to r.t. and filtered
t
via a Celite pad. The filtrate was taken up in BuOMe (200 ml) and washed with 2n HCl (80 ml), H2O
(3ꢁ80 ml), and brine (80 ml). The soln. was dried (MgSO4) and filtered. The solvents were evaporated
under reduced pressure. The crude product was subjected to bulb-to-bulb distillation (1008/10 mbar) to
give 5.4 g (41 mmol) of a light yellow liquid (purity: 96%; yield: 43%). 1H-NMR (400 MHz, CDCl3): 0.93
(d, J¼6.8, MeꢀC(3)); 0.93 (d, J¼6.6, MeꢀC(3)); 1.38 (ddd, J¼5.8, 7.8, 13.6, HaꢀC(2)); 1.52 (ddd, J¼6.6,
8.1, 13.6, HbꢀC(2)); 1.75–1.85 (m, HꢀC(3)); 4.22–4.28 (m, HꢀC(1)); 4.84–4.86 (m, CH2(3’)); 5.24 (ddd,
J¼6.6, 6.6, 6.6, HꢀC(1’)). 13C-NMR (400 MHz, CDCl3): 22.7 (q, MeꢀC(3)); 23.9 (q, MeꢀC(3)); 25.0 (d,
C(3)); 47.0 (t, C(2)); 68.5 (d, C(1)); 77.7 (t, C(3’)); 95.5 (d, C(1’)); 207.4 (s, C(2’)). EI-MS (70 eV): 111 (6),
87 (26), 70 (23), 69 (100), 57 (7), 45 (11), 43 (27), 41 (35), 39 (20), 27 (5).
Ethenyl 6-Methylhepta-1,2-dien-4-yl ether (63). From 62 as described for 9. Yield: 54% (purity:
94%). 1H-NMR (400 MHz, CDCl3): 0.94 (d, J¼6.8, Me2C(3)); 1.45 (ddd, J¼5.8, 7.3, 13.6, HaꢀC(2)); 1.68
(ddd, J¼6.6, 7.8, 13.6, HbꢀC(2)); 1.75–1.85 (m, HꢀC(3)); 4.05 (dd, J¼1.5, 6.6, HꢀC(2’)); 4.34 (dd, J¼1.5,
14.2, HꢀC(2’)); 4.30–4.34 (m, HꢀC(1)); 4.82 (ddd, J¼1.5, 6.3, 10.8, HaꢀC(3’)); 4.86 (ddd, J¼1.5, 6.6,
10.9, HbꢀC(3’)); 5.12 (ddd, J¼6.6, 6.6, 7.6, HꢀC(1’)); 6.38 (dd, J¼6.6, 14.2, HꢀC(1’)). 13C-NMR
(400 MHz, CDCl3): 22.8 (q, MeꢀC(3)); 23.1 (q, MeꢀC(3)); 24.8 (d, C(3)); 44.6 (t, C(2)); 76.7 (d, C(1));
76.8 (t, C(3)); 89.2 (t, C(2’)); 92.1 (d, C(1’)); 150.8 (d, C(1’)); 208.9 (s, C(2’)). EI-MS (70 eV): 137 (3, [Mꢀ
15]þ ), 109 (47), 96 (20), 81 (39), 67 (100), 55 (23), 53 (37), 43 (44), 41 (37), 39 (23).

CHEMISTRY & BIODIVERSITY – Vol. 11 (2014)
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(4E)-7-Methyl-3-methylideneoct-4-enal (64). 63 as described for 10. Yield: 67%. 1H-NMR
(400 MHz, CDCl3): 0.89 (d, J¼6.6, Me2C(7)); 1.62 (tqq, J¼6.8, 6.6, 6.6, HꢀC(7)); 2.01 (dd, J¼6.8, 7.3,
CH2(6)); 3.25 (dd, J¼1.0, 2.5, CH2(2)); 5.05 (br. s, 1 H of CH2¼C(3)); 5.20 (br. s, 1 H of CH2¼C(3)); 5.62
(dt, J¼15.9, 7.3, HꢀC(5)); 6.12 (br. d, J¼15.9, HꢀC(5)); 9.59 (t, J¼2.5, HꢀC(1)). 13C-NMR (400 MHz,
CDCl3):22.6 (q, Me2C(7)); 28.9 (d, C(7)); 42.5 (t, C(6)); 48.1 (t, C(2)); 118.4 (t, H2C¼C(3)); 132.0 (d,
C(5)); 137.7 (d, C(4)); 137.9 (s, C(3)); 200.8 (d, C(1)). EI-MS (70 eV): 152 (16, Mþ ), 137 (10, [Mꢀ15]þ ),
109 (48), 95 (83), 81 (100), 79 (68), 68 (42), 67 (73), 43 (35), 41 (52). Odor: Citral, citronellal, verbena,
lemongrass.
(4E)-7,9,9-Trimethyl-3-methylidenedec-4-enal (65). From 4-(ethenyloxy)-6,8,8-trimethylnona-1,2-
1
diene as described for 10. Yield: 47%. H-NMR (400 MHz, CDCl3): 0.90 (s, Me3C(9)); 0.92 (d, J¼6.8,
MeꢀC(7)); 1.05 (dd, J¼6.6, 13.9, HaꢀC(8)); 1.25 (dd, J¼3.54, 13.9, HbꢀC(8)); 1.55–1.65 (m, (HꢀC(7));
1.96 (dddd, J¼1.3, 7.3, 7.3, 18.9, HaꢀC(6)); 2.11 (dddd, J¼1.3, 7.1 7.1, 18.9, HbꢀC(6)); 3.25 (d, J¼2.5,
CH2(2)); 5.06 (br. s, 1 H of CH2¼C(3)); 5.21 (br. s, 1 H of CH2¼C(3)); 5.61 (ddd, J¼7.1, 7.5, 15.7,
HꢀC(5)); 6.17 (br. d, 15.7, HꢀC(4)); 9.60 (t, J¼2.5, HꢀC(1)). 13C-NMR (400 MHz, CDCl3): 22.9 (q,
MeꢀC(7)); 30.0 (s, C(7)); 30.4 (q, Me3C(7)); 31.5 (s, C(9)); 43.1 (t, C(6)); 48.1 (t, C(8)); 50.9 (t, C(8));
118.4 (t, CH2¼C(3)); 131.9 (d, C(4)); 132.1 (d, C(5)); 137.9 (s, C(3)); 200.8 (d, C(1)). EI-MS (70 eV): 208
(3, Mþ ), 175 (3), 137 (5), 110 (7), 109 (13), 95 (58), 81 (13), 79 (13), 57 (100), 41 (23). Odor: green,
aldehydic, fatty, sappy, slightly citrus, slightly metallic.
(4E)/(4Z)-5,7-Dimethyl-3-methylideneoct-4-enal (66). From 4,6-dimethylhepta-1,2-dien-4-yl ethenyl
ether as described for 10. Yield: 90% (two isomers; (E)/(Z) 1:1). Odor: aldehydic, green, fatty, orange,
mandarin. (E)-Isomer: 1H-NMR (400 MHz, CDCl3): 0.88 (d, J¼6.6, Me2C(7)); 1.79 (d, J¼1.5,
MeꢀC(5)); 1.80–1.90 (m, HꢀC(7)); 2.14 (dd, J¼1.0, 7.8, CH2(6)); 3.16 (dd, J¼1.3, 2.5, CH2(2)); 5.09 (br.
s, 1 H of CH2¼C(3)); 5.15 (br. s, 1 H of CH2¼C(3)); 5.58 (br. s, HꢀC(4)); 9.63 (t, J¼2.5, HꢀC(1)).
13C-NMR (400 MHz, CDCl3):18.4 (q, MeꢀC(5)); 22.8 q, Me2C(7)); 26.6 (d, C(7)); 50.6 (t, C(2)); 52.6 (t,
C(6)); 118.1 (t, CH2¼C(3)); 126.2 (d, C(4)); 137.5 (s, C(3)); 140.2 (s, C(5)); 200.6 (d, C(1)). EI-MS
(70 eV): 166 (2, Mþ ), 151 (14), 123 (43), 109 (100), 95 (39), 81 ( 31), 67 (26), 55 (15), 41 (20). (Z)-
1
Isomer: H-NMR (400 MHz, CDCl3): 0.88 (d, J¼6.6, Me2C(7)); 1.76 (d, J¼1.5, MeꢀC(5)); 1.80–1.90
(m, HꢀC(7)); 1.93 (dd, J¼1.0, 7.6, CH2(6)); 3.13 (dd, J¼1.3, 2.5, CH2(2)); 5.09 (br. s, 1 H of CH2¼C(3));
5.11 (br. s, 1 H of CH2¼C(3)); 5.58 (br. s, HꢀC(4)); 9.63 (t, J¼2.5, HꢀC(1)). 13C-NMR (400 MHz,
CDCl3): 22.9 (q, Me2C(7)); 24.2 (q, MeꢀC(5)); 26.7 (d, C(7)); 41.8 (t, C(6)); 52.8 (t, C(2)); 118.0 (t,
CH2¼C(3)); 126.2 (d, C(4)); 137.6 (s, C(3)); 140.2 (s, C(5)); 200.6 (d, C(1)). EI-MS (70 eV): 166 (2, Mþ ),
151 (15), 123 (39), 109 (100), 95 (29), 81 (29), 67 (26), 55 (15), 41 (18).
(4E)-7,11-Dimethyl-3-methylidenedodec-4-enal (67). From 6,10-dimethylundeca-1,2-dien-4-yl ethen-
yl ether as described for 10. Yield: 78%. 1H-NMR (400 MHz, CDCl3): 0.87 (d, J¼6.8, MeꢀC(11)); 0.89
(d, J¼6.8, MeꢀC(11)); 0.89 (d, J¼7.3, MeꢀC(7)); 1.08 (m, CH2(8), CH2(9), CH2(10)); 1.48 (m, HꢀC(7),
HꢀC(11)); 1.91–1.98 (m, HaꢀC(6)); 2.10–2.18 (m, HbꢀC(6)); 3.26 (dd, J¼1.0, 2.5, CH2(2)); 5.06 (br. s,
1 H of H2C¼C(3)); 5.20 (br. s, 1 H of H2C¼C(3)); 5.63 (ddd, J¼7.3, 8.3, 15.7, HꢀC(5)); 6.18 (br. d, J¼
15.7, HꢀC(4)); 9.63 (t, J¼2.5, HꢀC(1)). 13C-NMR (400 MHz, CDCl3): 1.92 (q, MeꢀC(7)); 23.0 (q,
MeꢀC(11)); 23.1 (q, MeꢀC(11)); 25.2 (t, C(9)); 28.4 (d, C(11)); 33.6 (d, C(7)); 33.6 (t, C(8)); 37.3 (t,
C(6)); 39.6 (t, C(10)); 48.2 (t, C(2)); 118.4 (t, H2C¼C(3)); 132.0 (d, C(4)); 137.6 (s, C(3)); 140.2 (s, C(5));
200.6 (d, C(1)). EI-MS (70 eV): 222 (2, Mþ ), 137 (12), 109 (29), 96 (29), 95 (100), 81 (27), 71 (35), 57
(43), 43 (34) 41 (29). Odor: aldehydic, sparkling, Coca Cola, hesperidic, waxy, resinous.
(4E)-7,11-Dimethyl-3-methylidenedodeca-4,10-dienal (68). From 6,10-dimethylundeca-1,2,9-trien-4-
yl ethenyl ether as described for 10. Yield: 32% (purity: 95%). 1H-NMR (400 MHz, CDCl3): 0.88 (d, J¼
6.8, MeꢀC(7)); 1.13–1.20 (m, HaꢀC(8)); 1.30–1.39 (m, HbꢀC(8)); 1.49–1.60 (m, HꢀC(7)); 1.62 (br. s,
MeꢀC(11)); 1.70 (br. s, MeꢀC(11)); 1.92–2.05 (m, CH2(9), HaꢀC(6)); 2.11–2.18 (m, HbꢀC(6)); 3.25 (dd,
J¼0.8, 2.5, CH2(2)); 4.78 (br. s, 1 H of CH2¼C(3)); 5.08–5.13 (m, HꢀC(10)); 5.20 (br. s, 1 H of
CH2¼C(3)); 5.62 (ddd, J¼7.3, 8.8, 15.7, HꢀC(5)); 6.18 (br. d, J¼15.7, HꢀC(4)); 9.60 (t, J¼2.5, HꢀC(1)).
13C-NMR (400 MHz, CDCl3): 18.0 (q, Me2C(11)); 19.8 (q, MeꢀC(7)); 26.0 (t, C(9)); 33.2 (d, C(7)); 37.1 (t,
C(8)); 40.6 (t, C(6)); 48.1 (t, C(2)); 118.4 (t, H2C¼C(3)); 125.1 (d, C(10)); 131.7 (s, C(11)); 131.8 (d,
C(5)); 132.8 (d, C(4)); 137.9 (s, C(3)); 200.7 (d, C(1)). EI-MS (70 eV): 220 (3, Mþ ), 176 (18), 135 (49),
109 (74), 95 (100), 81 (38), 69 (86), 55 (32), 41 (78). Odor: aldehydic, metallic, marine, citrus, waxy,
thyme.

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CHEMISTRY & BIODIVERSITY – Vol. 11 (2014)
3-Methylidene-5-propyloct-4-enal (69). From 4-(ethenyloxy)-4-propylhepta-1,2-diene as described
1
for 10. Yield: 59%. H-NMR (400 MHz, CDCl3): 0.90 (d, J¼7.3, Me(8)); 0.92 (d, J¼7.3, MeꢀC(3’));
1.39–1.46 (m, CH2(7), CH2(2’)); 2.04 (m, HaꢀC(6), HaꢀC(1’)); 2.18 (m, HbꢀC(6), HbꢀC(1’)); 3.14 (dd,
J¼1.0, 1.5, CH2(2)); 4.47 (br. s, 1 H of CH2¼C(3)); 5.10 (br. s, 1 H of CH2¼C(3)); 5.60 (br. s, HꢀC(4));
9.63 (t, J¼1.5, HꢀC(1)). 13C-NMR (400 MHz, CDCl3): 14.2 (q, C(8)); 14.6 (q, C(3’)); 21.5 (t, C(7)); 22.2
(t, C(2’)); 33.4 (t, C(6)); 39.4 (t, C(1’)); 52.8 (t, C(2)); 117.4 (t, CH2¼C(3)); 125.2 (d, C(4)); 137.6 (s, C(3));
145.2 (s, C(5)); 200.6 (d, C(1)). EI-MS (70 eV): 180 (2, Mþ ), 162 (5), 137 (100), 109 (40), 95 (29), 91
(15), 81 (24), 67 (20), 55 (14), 41 (13). Odor: fatty, iris, dry, woody.
(4E)-6,10-Dimethyl-3-methylideneundeca-4,9-dienal (70). From 5,9-dimethyldeca-1,2,8-trien-4-yl
ethenyl ether as described for 10. Yield: 59%. 1H-NMR (400 MHz, CDCl3): 1.02 (d, J¼6.8, MeꢀC(6));
1.32–1.38 (m, CH2(7)); 1.60 (br. s, MeꢀC(10)); 1.70 (br. s, MeꢀC(10)); 1.92–1.97 (m, CH2(8)); 2.16–2.17
(m, HꢀC(6)); 3.25 (dd, J¼0.5, 2.5, CH2(2)); 5.06 (m, 1 H of CH2¼C(3)); 5.07–5.11 (m, HꢀC(9)); 5.21
(m, 1 H of CH2¼C(3)); 5.51 (dd, J¼7.8, 15.9, HꢀC(5)); 6.15 (br. d, J¼15.9, HꢀC(4)); 9.60 (t, J¼2.5,
HꢀC(1)). 13C-NMR (400 MHz, CDCl3): 18.1 (q, MeꢀC(11)); 20.8 q, MeꢀC(6)); 26.1 (q, MeꢀC(11)); 26.2
(t, C(8)); 37.0 (d, C(6)); 37.4 (t, C(7)); 48.1 (t, C(2)); 118.5 (t, H2C¼C(3)); 124.0 (d, C(9)); 130.1 (d, C(4));
131.9 (s, C(10)); 138.0 (s, C(3)); 138.9 (d, C(5)); 200.8 (d, C(1)). EI-MS (70 eV): 206 (9, Mþ ), 191 (9),
163 (25), 135 (36), 107 (41), 95 (100), 69 (47), 67 (33), 55 (39), 41 (45). Odor: aldehydic, metallic,
watery, Aldoxal, rose oxide.
6,7-Dihydro-6,9,9-trimethyl-3a,6-ethano-2-benzofuran (80). Prop-2-yn-1-yl (4,6,6-trimethylcyclo-
hexa-1,3-dien-1-yl)methyl ether (1.0 g, 5 mmol) was dissolved in THF (60 ml). Potassium 2-methyl-
propan-2-olate (0.6 g, 5 mmol) was added at r.t. The mixture was stirred for 7 h at r.t. and filtered. The
solvent was evaporated under reduced pressure. The crude product was further purified by CC to give
1
0.4 g (2 mmol) of a light-yellow liquid (purity: 87%; yield: 37%). H-NMR (400 MHz, CDCl3): 0.81 (s,
MeꢀC(9)); 1.01 (s, MeꢀC(6)); 1.17 (d, J¼12.6, HaꢀC(8)); 1.17 (s, MeꢀC(9)); 1.23 (d, J¼12.6, HbꢀC(8));
1.92 (ddd, J¼2.1, 3.0, 15.7, HaꢀC(7)); 2.05 (dd, J¼2.0, 15.7, HbꢀC(7)); 4.14 (d, J¼9.6, HaꢀC(3)); 4.41 (d,
J¼9.6, HbꢀC(3)); 5.91 (d, J¼8.1, HꢀC(1)); 5.95 (dd, J¼2.0, 2.0, HꢀC(6)); 6.09 (d, J¼8.1, HꢀC(5)).
13C-NMR (400 MHz, CDCl3): 25.1 (q, MeꢀC(9)); 27.1 (q, MeꢀC(9)); 27.6 (q, MeꢀC(6)); 33.7 (t, C(7));
38.2 (s, C(6)); 38.6 (s, C(9)); 52.0 (t, C(8)); 58.2 (t, C(3a)); 73.6 (t, C(3)); 117.8 (s, C(7a)); 133.8 (d, C(5));
137.1 (d, C(6)); 137.5 (d, C(1)). EI-MS (70 eV): 190 (1, Mþ ), 134 (100), 133 (41), 119 (50), 106 (23), 105
(49), 91 (35), 77 (12), 53 (4), 39 (5). Odor: resinous, cypress, natural, pine needles, slightly fruity.
3a,4,5,6,7,7a-Hexahydro-3,6,6-trimethyl-4-methylidene-1-benzofuran (82). propadienyl 3,5,5-trime-
thylcyclohex-2-en-1-yl ether (81; 1.0 g, 5.6 mmol) was dissolved in DMF (70 ml) and stirred at 1208 for
1 h. The mixture was cooled to r.t. and poured onto H2O (150 ml). The aq. layer was extracted with Et2O
(3ꢁ80 ml). The combined org. layers were washed with brine (2ꢁ50 ml), dried (MgSO4), and filtered.
The solvent was evaporated under reduced pressure. The crude product was subjected to bulb-to-bulb
1
distillation to yield 0.4 g (2 mmol) of a light-yellow liquid (yield: 36%). H-NMR (400 MHz, CDCl3):
0.81 (s, MeꢀC(6)); 0.97 (s, MeꢀC(6)); 1.47 (br. dd, J¼9.1, 13.1, HꢀC(7)); 1.53 (br. s, MeꢀC(3)); 1.61
(ddd, J¼2.3, 6.6, 13.1, HꢀC(7)); 1.87 (br. d, J¼13.1, HaꢀC(5)); 1.96 (br. d, J¼13.1, HbꢀC(5)); 3.49 (br. d,
J¼7.3, HaꢀC(3)); 4.70 (ddd, J¼6.6, 7.3, 9.1, HaꢀC(7)); 4.82–4.83 (m, 1 H of CH2¼C(4)); 4.84–4.85 (m,
1 H of CH2¼C(4)); 6.05–6.06 (m, HꢀC(2)). 13C-NMR (400 MHz, CDCl3): 9.7 (q, MeꢀC(3)); 25.6 (q,
MeꢀC(6)); 31.3 (s, C(6)); 32.1 (q, MeꢀC(6)); 41.4 (t, C(7)); 45.5 (t, C(5)); 52.5 (d, C(3a)); 80.9 (d, C(7a));
112.3 (s, C(3)); 113.0 (t, CH2¼C(4)); 139.6 (d, C(2)); 145.0 (s, C(4)). EI-MS (70 eV): 178 (73), 163 (32,
[Mꢀ15]þ ), 145 (29), 122 (100), 121 (58), 107 (87), 93 (55), 91 (70), 79 (75), 41 (70).
6,8,8-Trimethyl-5-methylidenenonan-2-ol (84). Compound 10 (20.6 g, 113 mmol) was added drop-
wise to a 3m MeMgBr soln. (45.2 ml, 136 mmol) at 08 during 30 min. The mixture was stirred for 2 h,
allowing the temp. to rise to r.t. The mixture was poured onto ice-cold, sat. NH4Cl soln. (200 ml) and
diluted with 2n HCl (100 ml). tBuOMe was added (200 ml). The org. phase was washed with H2O (3ꢁ
100 ml) and brine (80 ml), dried (MgSO4), and filtered. The solvent was evaporated under reduced
pressure. The crude product was subjected to bulb-to-bulb distillation (1208/0.02 mbar) and further
purified by CC to yield 18.8 g (18 mmol) of a colorless liquid (yield 95%, two isomers, ratio 1:1). Odor
threshold: 250 ng/l air. Isomers A and B: 1H-NMR (400 MHz, CDCl3): 0.90 (s, Me3C(7)); 1.05 (d, J¼7.1,
MeꢀC(5)); 1.16 (dd, J¼5.6, 14.2, HaꢀC(6)); 1.23 (d, J¼6.3, MeꢀC(1)); 1.49 (ddd, J¼1.0, 6.1, 14.2,
HbꢀC(6)); 1.59–1.66 (m, CH2(2)); 1.99–2.31 (m, CH2(3), HꢀC(5)); 3.80–3.88 (m, HꢀC(1)); 4.68–4.69

CHEMISTRY & BIODIVERSITY – Vol. 11 (2014)
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(m, 1 H of CH2¼C(4)); 4.80–4.81 (m, 1 H of CH2¼C(4)). Isomer A: 13C-NMR (400 MHz, CDCl3): 23.5
(q, MeꢀC(5)); 24.0 (q, MeꢀC(1)); 29.8 (t, C(3)); 30.4 (q, Me3C(7)); 31.6 (s, C(7)); 37.4 (d, C(5)); 38.0 (t,
C(2)); 50.0 (t, C(6)); 68.5 (d, C(1)); 107.6 (t, CH2¼C(4)); 156.6 (s, C(4)). Isomer B: 13C-NMR (400 MHz,
CDCl3): 23.5 (q, MeꢀC(5)); 24.0 (q, MeꢀC(1)); 29.9 (t, C(3)); 30.4 (q, Me3C(7)); 31.6 (s, C(7)); 37.5 (d,
C(5)); 38.0 (t, C(2)); 50.1 (t, C(6)); 68.6 (d, C(1)); 107.6 (t, CH2¼C(4)); 156.8 (s, C(4)). EI-MS (70 eV):
Isomers A and B: 198 (1, Mþ ), 142 (5), 123 (22), 109 (31), 95 (18), 84 (32), 67 (24), 57 (100), 43 (44), 41
(34). Odor: floral, soapy, weak.
2,6,8,8-Tetramethyl-5-methylidenenonan-2-ol (86). From 88 as described for 84. Yield: 87%.
1H-NMR (400 MHz, CDCl3): 0.91 (q, Me3C(7)); 1.06 (d, J¼6.8, MeꢀC(5)); 1.17 (dd, J¼5.6, 14.2,
HaꢀC(6)); 1.27 (s, Me2C(1)); 1.51 (dd, J¼6.1, 14.2, HbꢀC(6)); 1.63 ꢀ1.67 (m, CH2(2)); 2.07–2.12 (m,
CH2(3)); 2.24–2.33 (m, HꢀC(5)); 4.68–4.69 (m, 1 H of CH2C¼C(4)); 4.80 (br. s, 1 H of CH2¼C(4)).
13C-NMR (400 MHz, CDCl3): 23.5 (q, MeꢀC(6)); 28.1 (t, C(3)); 29.8 (q, Me2C(1)); 30.4 (q, Me3C(7));
31.6 (s, (C(7)); 37.6 (d, C(5)); 42.6 (t, C(2)); 50.1 (t, C(6)); 71.4 (s, C(1)); 107.4, CH2¼C(4)); 157.0 (s,
C(4)). EI-MS (70 eV): 194 (7, Mþ ꢀ18), 179 (38), 138 (30), 123 (100), 95 (41), 81 (31), 59 (59), 57 (84),
43 (44), 41 (34). Odor: floral, fruity, fruity, rosy. Odour threshold: 757 ng/l air.
6,8,8-Trimethyl-5-methylidenenonan-2-one (88). Compound 84 (15.0 g, 76 mmol) was added
dropwise to a suspension of PCC (22.8 g, 106 mmol) and Celite (24.1 g) in CH2Cl2 at r.t. The temp. of
the mixture rose to358. The suspension was stirred for 2 h at r.t. and filtered. The solvent was evaporated
under reduced pressure. The crude product was subjected to bulb-to-bulb distillation (1108/0.02 mbar)
and further purified by CC to yield 13.0 g (66 mmol) of a colorless liquid (yield: 87%). 1H-NMR
(400 MHz, CDCl3): 0.89 (s, Me3C(7)); 1.04 (d, J¼6.8, MeꢀC(5)); 1.15 (dd, J¼5.6, 14.2, HaꢀC(6)); 1.49
(dd, J¼6.1, 14.2, HbꢀC(6)); 2.17 (s, MeꢀC(1)); 2.23–2.30 (m, CH2(3), HꢀC(5)); 2.58–2.62 (m, CH2(2));
4.58–4.59 (m, 1 H of CH2¼C(4)); 4.80 (br. s, 1 H of CH2¼C(4)). 13C-NMR (400 MHz, CDCl3): 23.4 (q,
MeꢀC(5)); 27.0 (t, C(3)); 30.3 (q, Me3C(7), MeꢀC(1)); 31.6 (s, C(7)); 37.8 (d, C(5)); 42.4 (t, C(2)); 49.8 (t,
C(6)); 107.6 (t, H2C¼C(4)); 155.4 (s, C(4)); 208.8 (s, C(1)). EI-MS (70 eV): 139 (15), 123 (21), 122 (52),
107 (30), 97 (24), 83 (20), 82 (15), 57 (74), 43 (100), 41 (24). Odor: green, fatty, rosy. Odour threshold:
452 ng/l air.
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Received February 11, 2014