A Practical Domino-Claisen–Cope Sequence in the Synthesis of New Blooming Citrus and Potent Floral Rose Alcohols

Article abstract of DOI:10.1002/hlca.201700200

Fifty years after its first discovery by Alan Francis Thomas, we describe a versatile, metal and pressure-free domino-Claisen–Cope rearrangement using the readily available α,β-unsaturated aldehydes 5 or their acetals 5′ and allylic alcohols 6. This transformation provides a convenient access to a large number of radiant citrus and floral rosy odorants. Odor profiles of novel floral rosy and citrus alcohols 13, 14, and 16 were studied. Compound 14ba has a floral, rosy, geranium-like character and shows unique performance and diffusiveness. Compound 16ba has a clear main citrus odor character with a clean green grapefruit/rhubarb connotation. Both odorants have been successfully introduced to perfumery recently as Rosyfolia (14ba) and Pomelol (16ba).

Full text of DOI:10.1002/hlca.201700200

Article Type: Full Paper
A Practical Domino-Claisen-Cope Sequence in the
Synthesis of New Blooming Citrus and Potent Floral Rose
Alcohols
Jie Liua,b), Yue Zoub), Lijun Zhoub), An Chaib), Chao Wangb), Hai-Shan Dangb),
Quanrui Wang*a), and Andreas Goeke*c)
a
b
c
)
Fudan University, Department of Chemistry, 220 Handan Road, Shanghai, 200433 (P. R. China),
e-mail: qrwang@fudan.edu.cn
)
Givaudan Fragrances (Shanghai) Ltd., Fragrance Ingredients Research, 298 Li Shi Zhen Road,
Shanghai, 201203 (P. R. China)
)
Givaudan Schweiz AG, Fragrance Ingredients Research, Überlandstrasse 138, 8600 Dübendorf,
Switzerland, Phone: +41448242379, e-mail: andreas.goeke@givaudan.com
In memory of Urs Müller
This article has been accepted for publication and undergone full peer review but has not
been through the copyediting, typesetting, pagination and proofreading process, which may
lead to differences between this version and the Version of Record. Please cite this article as
doi: 10.1002/hlca.201700200
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Abstract: 50 years after its first discovery by Alan Francis Thomas, we describe a versatile, metal
and pressure-free domino-Claisen-Cope rearrangement using the readily available α,β-unsaturated
aldehydes 5 or their acetals 5’ and allylic alcohols 6. This transformation provides a convenient
access to a large number of radiant citrus and floral rosy odorants. Odor profiles of novel floral rosy
and citrus alcohols 13, 14 and 16 were studied. Compound 14ba has a floral, rosy, geranium-like
character and shows unique performance and diffusiveness. Compound 16ba has a clear main citrus
odor character with a clean green grapefruit/rhubarb connotation. Both odorants have been
successfully introduced to perfumery recently as RosyfoliaTM (14ba) and PomelolTM (16ba).
Keywords: domino reactions • fragrances • Claisen rearrangement • Cope rearrangement • cyclopropanation
Supporting information for this article is given via a link at the end of the document.((Please delete this text if not appropriate))
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Introduction
‘O my Luve’s like a red, red rose’.[1] The blossoming grace of roses is an allegory of divine passion,
devotion and tenderness across cultures. Olfactorily, this notion is primarily conveyed by rose
alcohols: citronellol (30-40%), geraniol (10-20%), nerol (5%) and phenyl ethyl alcohol (PEA, 2-5%),
wherein the acyclic monoterpenoids often represent the lion’s share of the essential oil (Figure 1).[2a]
Citronellol 1 and geraniol 2 are primary monoterpenoid products of the mevalonic acid pathway of
aromatic plants[3] and are, therefore, almost omnipresent constituents of natural scents, for instance of
lily-of-the-valley flowers, palmarosa, geranium, lemon and gardenia species.[4] Apart from linalool,
these alcohols represent the most elementary components of what is called a ‘floral accord’ in
perfumery. However, the fragrance materials geraniol 2 and nerol 3 have been cited as a frequent
cause of allergic contact dermatitis, presumably by oxidation of the allylic double bond in vivo[5] and its
use is restricted in perfumery. Therefore, it is an important task to design novel floral, rosy and citrus
ingredients with significantly reduced skin sensitization risk.[6]
Sigmatropic rearrangements have proven very useful in the synthesis of these interconnected key
odorants, both on laboratory as well as on industrial scale.[2b,7] In a modification of the Claisen
rearrangement, Saucy and Marbet first reported[8] that treatment of isopropenyl methyl ether and 2-
methyl-butene-2-ol in an autoclave at about 140°C in the presence of an acid catalyst gave 6-methyl-
hept-5-en-2-one which, in turn, was converted into geraniol via acetylene addition, rearrangement and
reduction.[4] A pressure-free Hg-catalyzed domino-Claisen-Cope rearrangement for the preparation of
α,β-unsaturated aldehydes was pioneered in 1967 by Thomas[9] and later by Cookson[10a,b] and
others.[10c,d] Thomas successfully applied the reaction for the synthesis of the natural terpenes such
as torreyal[9a] and β-sinensal[9b] and a variety of different odorants.[9c-e] An atom-economical Hg-free
domino-Claisen-Cope process was patented by Hoffmann La Roche in 1973, claiming the direct
formation of citral form prenal 5a and prenol 6a via pyrolysis of its diprenyl acetal 7a.[11] In 1981, BASF
claimed an improved continuous process for the synthesis of citral[12a] and in subsequent years, this
procedure has been further optimized into one of the most elegant processes in fragrance industry
with a capacity of 40’000 tons (2004) of citral and its downstream derivatives citronellal, geraniol/nerol
and citronellol (Figure 1).[12] Several related Ireland-Claisen-Cope[13] and para-Claisen-Cope
sequences[14] with aromatic substrates were also described.
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Figure 1. Alcohols in Rose Oils and the Domino Claisen-Cope Sequence in the Continuous Process for their
Industrial Production.
It is probably due to the remarkable engineering complexity involved in the BASF continuous
process[12] and the toxicity of the Hg(OAc)2 catalyst used in the approach of Thomas,[9] that this
efficient domino transformation has not been used more frequently on laboratory scale. Consequently,
a systematic study on the scope of this atom-economic transformation has not been reported. Herein,
we describe our attempts to develop a greener, more sustainable one-pot, mercury and pressure-free
version of this domino-Claisen-Cope rearrangement to unsaturated aldehydes 10 as intermediates for
the synthesis of innovative floral and citrus odorants 13-16 (Scheme 1). Another motivation to
perform this study was to explore the possibility of selectively intercepting intermediate β,γ-aldehydes
9 (Scheme 1) as substrates for oxy-2-oxonia(azonia)-Cope rearrangements to compounds of type 12
which have been of interest to us during the past few years.[15]
Results and Discussion
We decided to systematically elaborate this transformation, by converting a wide range of unsaturated
aldehydes 5 and allyl alcohols 6 via intermediates 9 into a large number of radiant floral, citrus and
rosy odorants.
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Scheme 1. Domino-Claisen-Cope sequence as a key transformation for the synthesis of linear floral, citrus and
rosy alcohols (13, 14 and 16).
Both α,β-unsaturated aldehydes 5 and their dimethyl acetals 5’ could be used in this domino-Claisen-
Cope reaction. In presence of acid cat. A, consisting of triethanolamine and ortho-phosphoric acid
(Scheme 1), dimethyl acetals 5’ eliminate one equivalent of methanol to form vinyl ethers, which are
key substrates of the Saucy-Marbet reaction. Without isolation of the intermediate vinyl ether, the
equilibrium was driven towards the product side by continuously distilling off low boiling point by-
o
product methanol at slightly higher temperature than 70 C through a short fractional distillation
system. We initially chose to employ dimethyl acetals 5’ instead of the unprotected aldehydes 5,
because the former condense with alcohols 6 at lower temperature. These milder reaction conditions
allowed us to control the subsequent reaction cascade and stop it after the Claisen rearrangement (9)
without ensuing Cope rearrangement (10) which typically has a higher activation barrier.[16] We first
looked at the reaction between the dimethyl acetal of prenal (5’a) and crotyl alcohol (6b). Indeed,
Claisen product 9ab was formed as the main product (Table 1, entry 1), but due to R9 = H, the β,γ-
unsaturated aldehyde 9ac isomerized to more stable α,β-unsaturated aldehyde 9’ac resulting in a
relatively low yield under the reaction conditions (Table 1, entry 2). This had also been observed
previously in the synthesis of natural product lavandulal[17](9ac)(entry 2). When the dimethyl acetal of
2-methylpentenal (5’b) was used as a reaction partner with 6c, only Claisen product 9bc was
exclusively formed (entry 5). In fact, even when 9bc was heated at higher temperature, it still didn’t
convert into the Cope product 10bc. This likely happens simply because 9bc is the more
thermodynamically stable product. Compounds 9bb and 9bd could be obtained as the main products
(entries 4 and 6), when the reaction temperature was carefully controlled, and these reactions were
stopped at low conversion in order to prevent the Cope rearrangement occurring.
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Table 1. Domino-Claisen-Cope rearrangement procedure from dimethyl acetals (Method A).a
Entry
Substrate 5’
Substrate 6
Product 9
Product 10
(yield)b
(yield)b
1
2
5’a: R6 = R7 = R9 = H, R8 = Me
5’a: R6 = R7 = R9 = H, R8 = Me
6b: R1 = Me, R2 = R3 = R4 = R5 = H
6c: R1 = R2 = R3 = H, R4 = R5 = Me
9ab (41%)c
9ac (30%)c
10ab (0%)
10ac (0%)
3
4
5’b: R6 = R9 = Me, R7 = R8 = H
5’b: R6 = R9 = Me, R7 = R8 = H
5’b: R6 = R9 = Me, R7 = R8 = H
5’b: R6 = R9 = Me, R7 = R8 = H
5’b: R6 = R9 = Me, R7 = R8 = H
5’b: R6 = R9 = Me, R7 = R8 = H
5’b: R6 = R9 = Me, R7 = R8 = H
5’b: R6 = R9 = Me, R7 = R8 = H
5’c: R6 = R7 = R8 = H, R9 = Me
5’d: R6 = R9 = Et, R7 = R8 = H
6a: R1 = R2 = Me, R3 = R4 = R5 = H
6b: R1 = Me, R2 = R3 = R4 = R5 = H
6c: R1 = R2 = R3 = H, R4 = R5 = Me
6d: R1 = R2 = R4 = R5 = H, R3 = Me
6e: R1 = R2 = -(CH2)4-, R3 = R4 = R5 = H
6f: R1 = R2 = -(CH2)5-, R3 = R4 = R5 = H
6g: R1 = Me, R2 = R4 = R5 = H, R3 = Et
6h: Geraniol
9ba (0%)
9bb (36%)d
9bc (23%)
9bd (57%)d
9be (0%)
9bf (0%)
10ba (66%)
10bb (13%)
10bc (0%)
10bd (0%)
10be (20%)
10bf (32%)
10bg (79%)
10bh (68%)
10ca (64%)
10da (72%)
5
6
7
8
9
9bg (0%)
9bh (0%)
9ca (0%)
9da (0%)
10
11
12
6a: R1 = R2 = Me, R3 = R4 = R5 = H
6a: R1 = R2 = Me, R3 = R4 = R5 = H
a) Reaction conditions: method A: a mixture of acetal 5’ (1.0 eq.), allylic alcohol 6 (1.0 eq.) and catalyst A (0.5%) was heated below 130 oC for 3 h
to give the Claisen products 9, then heated at 160 oC for further 4 h to obtain cope products 10; volatile materials were removed during the reaction
process via a distillation system. All reactions were carried out on more than 20 gram scale. b) Isolated yields after column chromatography and
distillation. c) A mixture of 9 and 9’ was formed in these reaction, pure 9 only can be obtained after purification by column chromatography.d) heated
below 130 oC.
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For other substrates in Table 1, the selectivity for Claisen products 9 faded and could instead be
exclusively driven to Cope products 10 (entries 3, 7-12). With increasing steric demand in
intermediates 9 around R1 and/or R2 ≠ H, transition energies of the Cope rearrangement decreased
by Thorpe-Ingold effects.[18] A similar effect is apparent in case R3 ≠ H (R3 = Et, entry 9). We assume
that despite R2 = H, an increased population of s-cis conformations of intermediate 9bg facilitates the
Cope rearrangement. Moreover, when cyclopentylidene and cyclohexylidene derivatives of allyl
alcohols were used as substrates, the reactions resulted only in low yields of 10be and 10bf (entries
7, 8).
Table 2. One pot domino acetalization-Claisen-Cope rearrangement procedure (Method B)
Entry
Substrate 5
Substrate 6
Product 9 (yield)b
Product 10 (yield)b
1
(5b)
(6a)
(10ba) (62%)
(9ba) (0%)
2
5b
(6b)
(10bb) (58%)
(9bb) (0%)
3
5b
(6d)
(10bd) (62%)
(9bd) (0%)
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4
5b
(6e)
(10be) (38%)
(9be) (0%)
5
6
7
5b
5b
5b
(6f)
(10bf) (44%)
(9bf) (0%)
(6g)
(10bg) (54%)
(9bg) (0%)
(6h)
(10bh) (76%)
(9bh) (0%)
8
5b
(6i)
(10bi) (67%)
(9bi) (0%)
9
5b
(10bj) (52%)c
(6j)
(9bj) (49%)c
10
5b
(6k)
(10bk) (59%)
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(9bk) (0%)
11
5b
(6l)
(10bl) (67%)
(9bl) (0%)
12
5b
(6m)
(10bm) (37%)
(9bm) (0%)
13
5b
(6n)
(10bn) (17%)
(9bn) (0%)
14
5b
(6o)
(10bo) (75%)d
(9bo) (44%)d
15
5b
(6p)
(10bp) (47%)e
(9bp) (0%)
16
6j
(5c)
(10cj) (41%)
(9cj) (0%)
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17
5c
6k
(10ck) (40%)
(9ck) (0%)
(9ea) (0%)
(9eq) (0%)
18
6a
(5e)
(10ea) (30%)
19
5e
(6q)
(10eq) (29%)
20
6a
(9fa) (0%)
(10fa) (23%)
(5f)
21
6a
(5g)
(10ga) (42%)
(9ga) (0%)
22
6a
(5h)
(10ha) (28%)
(9ha) (0%)
23
6q
(5i)
(10iq) (32%)
(9iq) (0%)
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24
25
26
6a
(10ja) (12%)
(5j)
(9ja) (0%)
5b
(6c)
(10bc) (0%)
(9bc) (16%)
6c
(5a)
(10ac) (0%)
(9'ac) (72%)
a) Reaction conditions: method B: a mixture of aldehyde 5, allylic alcohol 6 and catalyst B (4.4 mol%) in xylene was refluxed for 20-48 hours.
b) Isolated yields after column chromatography and distillation. c) Using toluene as solvent, Claisen product 9bj can be isolated as main
product, 10bj was formed after further heating at 180 oC for 1 hour. d) Claisen product 9bo was obtained as the main product under standard
condition, 10bo was formed after further heating at 180 oC for 1 hour. e) A mixture of isomers of two Cope products.
Although this domino procedure commencing from dimethyl acetals 5’ is efficient and suitable for
keeping lower reaction temperatures, it requires pre-synthesis of acetals. However, the reaction
should also proceed from unsaturated aldehydes 5 and allyl alcohol substrates 6 directly, only
producing water as by-product. A representative standard reaction condition was elaborated:[19] in the
presence of Et3N hydrochloride, substrates 2-methylpentenal 5b and prenol 6a reacted in xylene at
o
130-140 C, while water was removed by Dean-Stark condenser. The higher reaction temperature
facilitated the Cope rearrangement and products 10 were obtained (Table 2, entry 1) predominantly.
The scope, yields and selectivities are summarized in Table 2. Various allyl alcohols 6 react with 2-
methylpentenal 5b to give Citral-like derivatives in good yields (Table 2, entries 1-15). Allyl alcohol
itself did not undergo this domino reaction with 2-methylpentenal 5b under these conditions due to its
low boiling point of 97°C and miscibility with water. On the other hand, the reaction of methallyl
alcohol 6d (b.p.:115 °C) proceeded well, but required long reaction time (about 2 days, due to the
reduced water removal efficiency) to get a reasonable conversion with prenol 6a (Table 2, entry 3).
The yields obtained by Method B were generally better (Table 2, entries 2-5) than those obtained by
Method A, with the exception of yields of compound 10ba and 10bg (Table 1, entries 3,9 vs Table 2,
entries 1,6). In order to investigate the scope of the reaction, Method B was further extended to
additional substrates. 2-Methylpentenal 5b reacted with a variety of allyl alcohols 6i-p, such as pent-
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2-enol (6i), cinnamic alcohol (6l), perilla alcohol(6m) or sorbyl alcohol (6p) to give products 10 in
modest to good yields (Table 2, entries 8-12). The phenyl group of cinnamic aldehyde was compatible
with the reaction conditions yielding (2E,6E)-2,4-dimethyl-7-phenylhepta-2,6-dienal 10bl in a yield of
67% along with 5% of the (2Z)-isomer. The reaction of 5b with (2E,4E)-hexa-2,4-dien-1-ol 6p resulted
in a mixture of two constitutional isomers 10bp and 10bp’ in a ratio of 35:65 and an isolated yield of
47% (Table 2, entry 15).[20]
Reactions with secondary allyl alcohols 6n and 6o successfully generated 10bn and 10bo
(entries 13,14). The yield of product 10bn was low, due to competitive dehydration of 6n to 2-methyl-
1,3-petadiene, indicated by the formation of Diels-Alder products of this diene with aldehyde 5b.
Notably, the Claisen product 9bj and 9bo (Table 2, entries 9,14) could be separated as main products
under the standard reaction conditions at 130-140 oC. But when the reaction temperature was
increased to 170 oC, the Cope products 10j and 10bo were exclusively obtained. We did not study the
chirality transfer in case secondary allyl alcohols were optically active, since asymmetric Clasien
rearrangements have been well investigated[21]. Furthermore, differently substituted unsaturated
aldehydes 5 were submitted to this transformation, such as tiglic aldehyde 5c, cyclohex-1-ene-1-
carbaldehyde 5e, hexenal 5g as well as heptenal 5h. Cope products 10 were obtained in modest
yields (Table 2, entries 16-23). Again, when R9 = H (entries 21, 22), ,-unsaturated intermediates 9
tended to isomerize into their conjugated analogues 9’ (Table 1), while increasing steric demand in
cycloalkene carbaldehydes 5e and 5f resulted in competitive side reactions and lower yields of Cope
products 10 (entries 18-20). Rearrangement product 10ja was isolated in low yield from a reaction of
cyclopentenone (5j) with prenol (6a) (Table 2, entry 24). Finally, the tertiary alcohol 2-methyl-but-3-en-
2-ol (6c) underwent Claisen rearrangement with compound 5b to form aldhyde 9bc albeit in low yield
of 16%, but did not proceed to the Cope rearrangement (Table 2, entry 25). Similarly, the reaction of
prenal 5a (R9 = H) and alcohol 6c exclusively generated the ,-unsaturated aldehyde 9’ac (Table 2,
entry 26). Several aldehydes 10 possessed interesting fresh and clean, citral-like odors which are
described within the experimental section, as well as improved skin sensitization properties in
comparison to citral.
In order to discover new floral, rosy and citrus odorants and to investigate Structure-Odor
Relationships (SOR’s) in this field, further efforts were made to synthesize derivatives from these
aldehyde building blocks according to Scheme 1. Alcohols were the main targets, since they are
hedonically attractive, stable in perfume applications and often biodegradable. The structures of
synthesized derivatives 13 and their odor descriptions are summarized in Figure 2. Compound 13ba
had a pleasant fresh, rosy, geranium and citrus odor, significantly stronger than geraniol. The sought
after citrusy freshness of this rosy odorant 13ba turned into more floral fatty connotations for
derivatives with both less (13bb, 13bi) and more branched derivatives (13bj, 13bo). Methallyl alcohol
derived 13bd was less substantive in comparison to geraniol. Cyclic odorants 13ea and 13eq
possessed strong, floral notes while their ring-opened derivatives 13da and 13ha imparted weak
sensations. Odorants 13eq and 13ia, generated from tiglic alcohol, showed sandalwood facets, a well
known olfactory transition in the family of rose and lily-of-the-valley odor family.[2b]
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However, the ,-double bond in compounds 13 have been associated with a certain risk of skin
sensitization which is well known in the case of geraniol.[22] Therefore, we synthesized regulatorily
safer derivatives 14 and 16. Cyclopropanes are considered isosteres of double bonds and their
biological properties may well differ from the olefins. They may stabilize olefins and slow down
undesired metabolic pathways.[23] Inspired by the chemistry of Javanol,[24] the allylic double bonds of
the geraniol analogues 13 were cyclopropanated by the selective Grignard-based cyclopropanation
method that had been previously established by Schröder at al.[25] Cyclopropanation of the allylic
alcohol 13ba led to 14ba as a mixture of two diastereomers. Another product of perfumery interest in
this series was 14bb having a floral milky, creamy, sandalwood-like note as a mixture of 4 isomers.
Biscyclopropanation at the position of the distal double bond was <2%. The outstanding performance
of 14ba among a series of cyclopropanated and non-cyclopropanated analogues was unique. The
odorant was described as floral, rosy, geraniol-like odor of fresh natural petally radiance and a tea-like
dry down. Givaudan filed a patent in 2011[26] and introduced 14ba as new captive ingredient under the
name RosyfoliaTM. For instance, RosyfoliaTM was used in the new Eau de Toilette Missoni of Angela
Missoni by perfumer Quentin Bisch, featuring a bouquet of blood orange, pink berries with nuances of
nashi pear and watery flowers.
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Figure 2.Olfactory Profiles for linear floral, citrus and rosy alcohols 13, 14 and 16.
The two diastereoisomers of 14ba were
chromatographically separated and their relative
configurations were determined by NMR analysis of their para-nitro benzoic acid esters.[19] Both
isomers possessed similar odor qualities, but surprisingly, the odor threshold of the anti-isomer 14ba’’
(0.028 ng/L air) was 100 times lower than that of the syn-isomer. Recently, Takasago has reported
similar findings in a series of odorants in which the prenyl unit was replaced by a phenyl ring.[27] In
addition to the cyclopropanated compounds 14, a series of mono-unsaturated hydroxy compounds
16 was prepared by hydrogenation of the ,-unsaturated aldehydes 10 to intermediate aldehydes 15,
followed by sodium borohydride reduction to compounds 16. The odor of compounds 16 differed
significantly from those of 13 and 14 and, as a trend, were more fresh, citrus-like (Figure 2). Again,
16ba, consisting of 2 isomers in a ratio of 55:45, was most appreciated by perfumers because of its
clean and fresh citrus, green grapefruit and rhubarb connotation.[28] The olfactory differences between
the two isomers were not very pronounced, as evaluated by GC-sniff methods. Besides its odour
profile, 16ba enhances the freshness and cleanliness attributes of a perfumed product to which it is
added without changing the overall odor profile. Mixture 16ba was recently trademarked PomelolTM
.
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Figure 3. Olfactory properties and odor thresholds of isomers of 10-16ba.
Conclusions
In summary, we described an optimized general, pressure and mercury-free domino-Claisen-Cope
rearrangement using readily available α,β-unsaturated aldehydes 5 and allylic alcohols 6 to provide a
convenient approach to a series of hepta-2,6-dienals 10 (citral-like derivatives). In case unsaturated
acetals 5’ are used, the method also allows interception of intermediate Claisen products 9 in good
yields and selectivities. This sustainable method is practical and easy to scale up. In addition, the
modified protocol enabled us to efficiently access novel performing fragrance ingredients which are
structurally related to the classics of industrial perfumery. As a result, the new non-allergenic perfume
ingredient RosyfoliaTM and PomelolTM were recently commercialized, having an outstanding radiance
and the lowest odor threshold measured in this family of odorants.
Acknowledgements ((optional))
We thank Dr. G. Brunner for NMR experiments and G. Tang (Fudan University) for high-resolution
mass spectrometry data and Prof. Paul Davey and Dr. Nicolas Armanino for proof reading of the
manuscript. The financial support from the NNSFC under Grant 21372045 is gratefully acknowledged.
Experimental Part
General Experimental Information
All reactions were performed under argon using solvents and reagents from commercial suppliers without further
purification. Solvents for extraction and chromatography were technical grade and used without further
purification. Flash chromatography was performed using Tsingdao Haiyang Chemical silica gel (200 – 300 mesh)
and silica gel Merck grade (60 Å). Unless otherwise noted, a mixture of PE (60-90 °C):MTBE was used as eluent.
NMR spectra were recorded with AW 300 and AV 500 MHz Bruker spectrometer instruments. The chemical shifts
1
for H NMR spectra was reported in δ (ppm) referenced to the residual proton signal of the deuterated solvent;
coupling constants were expressed in Hertz (Hz). 13C NMR spectra were referenced to the carbon signals of the
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deuterated solvent; the nature of the carbons (C, CH, CH2, or CH3) was determined by recording the DEPT90
1
and DEPT135 experiments; for complete assignments of H-NMR signals, COSY, NOESY, and ROESY 2D- or
1D-NMR methods were applied; for complete assignments of 13C-NMR signals, HMBC and HSQC 2D-NMR
methods were employed. The following abbreviations are used: s = singlet, d = doublet, t = triplet, q = quartet, m
= multiplet, dd = double doublet, bs = broad singlet. IR spectra were recorded with a Bruker Tensor 27. Melting
points were determined using a SGW X-4 micro hot-stage apparatus and are uncorrected. GC/MS spectral data
were obtained from an Agilent 6890 N and MSD 5975 using a column HP-5 MS, 30 m, 0.25 mm, 0.25 μm. High
resolution mass spectra were determined on a Thermo Fisher Scientific LTQ FT Ultra (ESI-MS) and Waters
Micromass GCT Premier (EI-MS).
General Procedures of the Claisen and domino-Claisen-Cope Rearrangements to aldehydes 9 and 10.
General Method A: A mixture of acetal 5’ and alcohol 6 was charged into a three-necked reaction flask equipped
with a thermometer, a 35 cm vacuum-jacked column filled with Sulzer packing and including a distillation head.
Catalyst A, triethanolamine-H3PO4 (cat. A, 1 w/w %, prepared by pre-mixing orthophosphoric acid (85%) with
triethanolamine (1:1) in acetic acid (3 mL)) was added and the mixture was heated to 130 oC for 3-10 hours to
give the Claisen products, or heated at 160 oC for 4 hours to give the Cope products. During this period, volatile
by-products were collected through the distillation head, and the reaction was monitored by GC. The remaining
oil was distilled in vacuo to give 9 and/or 10.
General Method B: A mixture of aldehyde 5 (1.0 –1.5 eq.), allylic alcohol 6 (1.0 eq.) and Et3N-HCl (cat. B, 4.4
o
mol%) in xylene was heated to 130-180 C at reflux for 20 hours. During this period, water was collected and
removed from the Dean-Stark apparatus. After cooling to room temperature, the reaction mixture was diluted with
MTBE, and washed with water and brine, dried with MgSO4, filtered, then concentrated under reduced pressure
to give the crude product, which was purified by distillation to afford 9 or 10.
3-Methyl-2-(prop-1-en-2-yl)pent-4-enal (9ab). A solution of acetal 1,1-dimethoxy-3-methylbut-2-ene 5’a (130 g,
1.00 mol) and (E)-but-2-en-ol 6b (72.1 g, 1.00 mol) were charged into a 500 mL three-necked reaction flask
equipped with a thermometer, a 35 cm vacuum-jacked column filled by Sulzer packing and with a distillation head
on top. The triethanolamine-H3PO4 (cat. A; 1.30 g, 1 w/w %), prepared by pre-mixing orthophosphoric acid (85%)
with triethanolamine (in 1:1 equivalent), was dissolved in acetic acid (3 mL), and then added to the reaction
mixture at room temperature. The mixture was heated slowly to 130 °C over 4 hours under argon, then heated for
a further 6 hours at 130 °C. During this period, volatile by-products were distilled off and the reaction was
monitored by GC. The remaining oil was distilled (75 °C/5 mbar) in vacuo to give 3-methyl-2-(prop-1-en-2-yl)pent-
4-enal 9ab (64.0 g, 41%, purity 90%, two isomers in a ratio of 13 : 87) as a colourless oil. An analytical sample
was purified by column chromatography (PE : MTBE = 200:1) followed by bulb-to-bulb distillation
1
(80°C/0.10mbar): H NMR (300 MHz, CDCl3): 9.46 (d, J = 2.5 Hz, 1H), 5.81-5.58 (m, 1H), 5.18-4.85 (m, 4H),
2.87-2.65 (m, 2H), 1.72 (s, 3H, Me), 0.99 (d, J = 6.1 Hz, 3H, Me) ppm. 13C NMR (75 MHz, CDCl3): 200.6 (d),
141.2 (d), 139.0 (s), 116.3 (t), 115.1 (t), 65.7 (d), 36.3 (q), 21.5 (q), 17.6 (q) ppm. IR (neat): 2974, 1723, 1641,
1454, 1375, 990, 676 cm-1. GC/MS(EI): m/z (%): 138 (1) [M+], 123 (7), 109 (17), 95 (18), 83 (87), 67 (35), 55
(100). HRMS (EI): m/z [M+], calcd for C9H14O: 138.1039; found: 138.1042. Odor description: green, sulfuratious,
vegetable, petal and herbaceous, pungent.
5-Methyl-2-(prop-1-en-2-yl)hex-4-enal (9ac, lavandulal).[17] A mixture of acetal 1,1-dimethoxy-3-methylbut-2-
ene 5’a (60.0 g, purity 98%, 452 mmol), allyl alcohol 6c (38.9 g, 452 mmol) and cat. A (0.6 g) was heated below
130 °C for 4 h to give 5-methyl-2-(prop-1-en-2-yl)hex-4-enal 9ac (20.6 g, 30%, b.p. 60 °C/4mbar, colorless oil).[17]
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1H NMR (300 MHz, CDCl3): 9.49 (s, 1H), 5.10-4.96 (m, 2H), 4.88 (s, 1H), 2.95 (t, J = 7.3 Hz, 1H), 2.59-2.42 (m,
1H), 2.32-2.14 (m, 1H), 1.70 (s, 3H, Me), 1.67 (s, 3H, Me), 1.62 (s, 3H, Me). 13C NMR (75 MHz, CDCl3): 201.2 (d),
140.2 (s), 133.6 (s), 120.6 (d), 115.3 (t), 60.6 (d), 25.9 (t), 25.7 (q), 21.2 (q), 17.8 (q) ppm. GC/MS(EI): m/z (%):
152 (6) [M+], 137 (12), 123 (20), 109 (32), 91 (13), 84 (43), 67 (100), 53 (15).
5-Methyl-2-(propan-2-ylidene)hex-4-enal (9'ac). Method B. A solution of ,-unsaturated aldehyde 3-methylbut-
2-enal 5a (156 g, 1.86 mol), allyl alcohol 6c (100 g, 1.16 mol) and triethylamine hydrochloride (6.39 g, 46.4 mmol)
in xylene (200 mL) was heated at 110 – 120 °C for 48 h to give 5-methyl-2-(propan-2-ylidene)hex-4-enal 9'ac
(128 g, 72%, b.p. 79 °C/4 mbar, colorless oil) 1H NMR (300 MHz, CDCl3 ): 10.09 (s, 1H), 4.87 (t, J = 6.6 Hz, 1H),
2.95 (d, J = 6.6 Hz, 2H), 2.17 (s, 3H, Me), 1.95 (s, 3H, Me), 1.68 (s, 3H, Me), 1.63 (s, 3H, Me) ppm. 13C NMR (75
MHz, CDCl3): 190.6 (d), 155.2 (s), 136.4 (s), 131.8 (s), 121.8 (d), 25.6 (q), 24.3 (t), 23.4 (t), 19.4 (q), 17.8 (q) ppm.
IR (neat): 2916, 1663, 1628, 1445, 1375, 1312, 1155, 1050, 894, 842 cm-1. GC/MS (EI): m/z (%): 152 (44) [M+],
137 (100), 119 (22), 109 (60), 91 (27), 81 (43), 67 (71), 53 (23). HRMS (EI): m/z [M+], calcd for C10H16O:
152.1196; found: 152.1203. Odor description: medicinal, solvent-like.
2-(But-3-en-2-yl)-2-methylpent-3-enal (9bb). Method A. A mixture of acetal 1,1-dimethoxy-2-methylpent-2-ene
5’b (144 g, 1.00 mol), (E)-but-2-en-ol 6b (72.1 g, 1.00 mol) and triethanolamine-H3PO4 (1.45 g) was heated at
130°C for 8 h and distilled to give 2-(but-3-en-2-yl)-2-methylpent-3-enal 9bb (73.0 g, 36 %, 64 °C/3 mbar,
colorless oil). An analytical sample was purified by column chromatography (PE : EA = 100 : 1) followed by bulb-
1
to-bulb distillation. H NMR (300 MHz, CDCl3): 9.38 (s, 1H), 5.80-5.38 (m, 3H), 5.05-5.00 (m, 2H), 2.66-2.52 (m,
1H), 1.75 (d, J = 5.7 Hz, 3H, Me), 1.07 (s, 3H, Me), 0.97 (d, J = 6.8 Hz, 3H, Me) ppm. 13C NMR (75 MHz, CDCl3):
202.9 (d), 139.1 (d), 130.0 (d), 128.4 (d), 115.9 (t), 54.7 (s), 42.2 (d), 18.5 (q), 14.8 (q), 17.3 (q) ppm. IR (neat):
2952, 1725, 1377, 1127, 1035, 706 cm-1. GC/MS (EI): m/z (%): 152 (1) [M+], 137 (3), 123 (14), 109 (4), 98 (100),
91 (10), 81 (37), 69 (21), 55 (42). HRMS (EI): m/z [M+], calcd for C10H16O: 152.1196; found: 152.1197. Odor
description: woody, floral, violet, orris, herbaceous, astringent.
2,5-Dimethyl-2-(prop-1-en-1-yl)hex-4-enal (9bc) Method A. A mixture of acetal 1,1-dimethoxy-2-methylpent-2-
ene 5’b (144 g, 1.00 mol), 2-methylbut-3-en-2-ol 6c (72.1 g, 1.00 mol) and triethanolamine-H3PO4 (1.44 g) was
heated at 130°C for 8 h to give 9bc (28.3 g, 23%, colorless oil). Alternatively, prepared according to general
procedure Method B, a solution of ,-unsaturated aldehyde 5b (68.4 g, 697 mmol), allyl alcohols 6c (50.0 g, 581
mmol) and triethylamine hydrochloride (7.99 g) in xylene (150 mL) was heated at 130°C for 48 hours to give 9bc.
(15.0 g, yield 16%, 62°C/5mbar, colorless oil) 1H NMR (300 MHz, CDCl3): 9.33 (s, 1H), 5.57-5.32 (m, 2H), 5.07-
4.96 (m, 1H), 2.34-2.12 (m, 2H), 1.74-1.63 (m, 6H), 1.57 (s, 3H, Me), 1.08 (s, 3H, Me) ppm. 13C NMR (75 MHz,
CDCl3): 202.9 (d), 134.5 (s), 131.5 (d), 127.5 (d), 118.6 (t), 52.3 (s), 34.3 (t), 25.8 (q), 18.4 (q), 18.3 (q), 17.8 (q)
ppm. IR (neat): 2969, 2932, 1724, 1689, 1452, 1377, 1165, 970 cm-1. GC/MS (EI): m/z (%):166 (1) [M+], 151 (1),
137 (3), 123 (1). 107 (6), 98 (100), 83 (17), 69 (74), 55 (10). HRMS (EI): m/z [M+], calcd for C11H18O: 166.1352;
found: 166.1361. Odor description: citrus, strong.
2-Methyl-2-(2-methylallyl)pent-3-enal (9bd). Method A. A mixture of acetal 1,1-dimethoxy-2-methylpent-2-ene
5’b (72.1 g, 0.50 mol), 6d (36.1 g, 0.50 mol) and triethanolamine-H3PO4 was heated at 130°C for 8 h to give 9bd
1
(43.2 g, 57%, b.p. 62°C/0.1mbar, colorless oil). H NMR (300 MHz, CDCl3): 9.38 (s, 1H), 5.53 (dq, J = 16.3, 6.2
Hz, 1H), 5.38 (d, J = 16.3 Hz, 1H), 4.81 (s, 1H), 4.66 (s, 1H), 2.41 (d, J = 13.9 Hz, 1H), 2.26 (d, J = 13.9 Hz, 1H),
1.71 (d, J = 5.7 Hz, 3H, Me), 1.65 (s, 3H, Me), 1.13 (s, 3H, Me) ppm. 13C NMR (75 MHz, CDCl3): 201.5 (d), 140.5
(s), 130.8 (d), 126.6 (d), 113.9 (t), 50.7 (s), 43.2 (t), 23.2 (q), 17.4 (q), 17.3 (q) ppm. IR (neat): 2973, 1724, 1462,
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1385, 1127, 1035, 706 cm-1. GC/MS (EI): m/z (%):152 (1) [M+], 137 (7), 123 (49). 109 (54), 95 (27), 81 (100), 67
(35), 55 (26). HRMS (EI): m/z [M+], calcd for C10H16O: 152.1196; found: 152.1207. Odor description: green,
vegetable, fruity, watery, touch citrus.
2,4,7-Trimethylocta-2,6-dienal (10ba). Method A. A mixture of acetal 1,1-dimethoxy-2-methylpent-2-ene 5’b
(500 g, 3.28 mol) and 3-methylbut-2-en-1-ol 6a (296 g, 3.44 mol) and triethanolamine-H3PO4 (3.0 g) was heated
slowly to 120 °C (pot temp.) over 2 h and heated for further 2 h at this temperature. Then the reaction mixture
was heated to 170 °C over 2 h, and heated for a further 2 hours at 170 °C. During this period, volatile materials
and by-products were distilled off and the reaction was monitored by GC. The reaction mixture was allowed to
cool to room temperature and the remaining oil was distilled in vacuo (60 °C/0.1 mbar) to give 2,4,7-
trimethylocta-2,6-dienal 10ba (380 g, 66%, purity 95%, E/Z= 95:5, colourless oil). Method B. A solution of 2-
methylpent-2-enal 5b (490 g, 4.99 mol), 3-methylbut-2-en-1-ol 6a (860 g, 9.98 mol), triethylamine hydrochloride
(30 g) and xylene (50 mL) was stirred and heated at reflux for 48 h to give 2,4,7-trimethylocta-2,6-dienal 10ba
(526 g, 62%, 103 °C/20 mbar, purity 98%, E/Z = 95: 5). 1H NMR (300 MHz, CDCl3): 9.37 (s, 1H), 6.27 (d, J = 9.9
Hz, 1H), 5.05 (t, J = 7.3 Hz, 1H), 2.80-2.62 (m, 1H), 2.22-1.91 (m, 2H), 1.72 (s, 3H, Me), 1.67 (s, 3H, Me), 1.59 (s,
3H, Me), 1.05 (d, J = 6.7 Hz, 3H, Me) ppm. 13C NMR (75 MHz, CDCl3): 195.6 (d), 160.1 (d), 137.9 (s), 133.5 (s),
121.3 (d), 34.8 (t), 34.2 (d), 25.7 (q), 19.4 (q), 17.9 (q), 9.3 (q) ppm. IR (neat): 2966, 2927, 1685, 1638, 1453,
1378, 1246, 1019, 878, 824, 676 cm-1. GC/MS (EI): m/z (%):166 (3) [M+], 151 (1), 137 (1), 124 (1), 109 (2), 98
(100), 83 (11), 69 (85), 53 (9). HRMS (EI): m/z [M+], calcd for C11H18O: 166.1352; found: 166.1356. Odor
description: citrus citral, aldehydic, metallic, green.
2,4-Dimethylocta-2,6-dienal (10bb). Method B. A solution of (E)-2-methylpent-2-enal 5b (123 g, 1.25 mol), (E)-
but-2-en-1-ol 6b (142 g, 1.87 mol), triethylamine hydrochloride (8.60 g, 0.063 mol) in xylene (50 mL) was refluxed
for 2 days to give 2,4-dimethylocta-2,6-dienal 10bb (119 g, 58%, purity 92%, b.p. 65 °C/0.17 mbar, 2E/2Z =
1
95.5:4.5, 6E/6Z = 73:27). H NMR (300 MHz, CDCl3): 9.34 (s, 1H), 6.30-6.17 (m, 1H), 5.55-5.22 (m, 2H), 2.83-
2.59 (m, 1H), 2.25-1.94 (m, 1H), 1.70 (s, 3H, Me), 1.59 (d, J = 6.2 Hz, 3H, Me), 1.02 (d, J = 6.7 Hz, 3H, Me) ppm.
13C NMR (75 MHz, CDCl3): Major isomer (2E,6E): 195.5 (d), 159.8 (d), 137.9 (s), 128.0 (d), 127.3 (d), 39.4 (t),
33.8 (d), 19.3 (q), 17.9 (q), 9.3 (q) ppm. Minor isomer(2E,6Z): 195.4 (d), 159.6 (d), 138.0 (s), 127.2 (d), 125.8 (d),
33.8 (d), 33.5 (t), 19.3 (q), 17.8 (q), 9.3 (q) ppm. IR (neat): 2962, 1685, 1453, 1378, 1017, 967, 820, 676 cm-1.
GC/MS (EI): m/z (%): 152 (5) [M+], 137 (3), 123 (10), 109 (2), 98 (100), 83 (22), 69 (24), 55 (60). HRMS (EI): m/z
[M+], calcd for C10H16O: 152.1196; found: 152.1203. Odor description: hesperidic, citrus, grapefruit.
2,4,6-Trimethylhepta-2,6-dienal (10bd). Method B. A solution of aldehyde 5b (114 g, 1.16 mol), allyl alcohol 6d
(70.0 g, 0.97 mol) and triethylamine hydrochloride (6.01 g) in xylene (100 mL) was heated at 140 °C for 48 h to
1
give 10bd. (90.9 g, 62%, 2E/2Z = 96:4, 69°C/0.2mbar, colorless oil). H NMR (300 MHz, CDCl3): 9.34 (s, 1H),
6.22 (dd, J = 9.7, 1.2 Hz, 1H), 4.71 (s, 1H), 4.63 (s, 1H), 2.98-2.78 (m, 1H), 2.16-1.97 (m, 2H), 1.72 (d, J = 1.2 Hz,
3H, Me), 1.66 (s, 3H, Me), 1.02 (d, J = 6.7 Hz, 3H, Me) ppm. 13C NMR (75 MHz, CDCl3): Major isomer (2E):
194.4 (d), 158.9 (d), 141.9 (s), 136.9 (s), 111.4 (t), 43.8 (t), 30.6 (d), 21.3 (q), 18.5 (q), 8.2 (q) ppm. Minor isomer
(2Z): 190.2 (d), 153.8 (d), 141.8 (s), 133.8 (s), 111.8 (t), 43.7 (t), 28.3 (d), 21.4 (q), 20.2 (q), 15.3 (q) ppm. IR
(neat): 2966, 1684, 1647, 1454, 1377, 1239, 1017, 888, 673 cm-1. GC/MS (EI): m/z (%): 152 (4) [M+], 137 (36),
123 (31), 109 (70), 95 (94), 81 (42), 69 (100), 55 (54). HRMS (EI): m/z [M+], calcd for C10H16O: 152.1196; found:
152.1207. Odor description: citrus, citral, fruity, ketonic, methyl heptenone.
6-Cyclopentylidene-2,4-dimethylhex-2-enal (10be). Method A.
A mixture of acetal 1,1-dimethoxy-2-
methylpent-2-ene 5’b (72.1 g, 0.50 mol), alcohol 6e (56.1 g, 0.50 mol) and triethanolamine-H3PO4 was heated at
160 °C for 6 h to give 10be (20.2 g, 20%). Alternatively, method B. A solution of aldehyde 5b (55.1 g, 562 mmol),
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allyl alcohol 6e (45.0 g, 281 mmol) and triethylamine hydrochloride (1.74 g) in xylene (150 mL) was heated at
1
140 °C for 24 h to give 10be (21.0 g, 39%, E/Z = 96: 4, bp.: 135°C/ 0.15mbar, colorless oil). H NMR (300 MHz,
CDCl3): 9.35 (s, 1H), 6.27 (d, J = 9.8 Hz, 1H), 5.23-5.09 (m, 1H), 2.82-2.61 (m, 1H), 2.31-1.95 (m, 6H), 1.72 (s,
3H, Me), 1.68-1.47 (m, 4H), 1.05 (d, J = 6.6 Hz, 3H, Me) ppm. 13C NMR (75 MHz, CDCl3): 195.6 (d), 160.2 (d),
145.3 (s), 137.9 (s), 116.7 (d), 36.3 (t), 34.1 (d), 33.6 (t), 28.9 (t), 26.4 (t), 26.3) (t), 19.4 (q), 9.3 (q) ppm. IR (neat):
2956, 1686, 1638, 1453, 1313, 1243, 1017, 869, 826, 675 cm-1. GC/MS (EI): m/z (%): 192 (3) [M+], 150 (1), 135
(1), 98 (100), 95 (99), 79 (11), 67 (34), 55 (9). HRMS (EI): m/z [M+], calcd for C13H20O: 192.1509; found:
192.1516. Odor description: fruity, rosy, citrus.
6-Cyclohexylidene-2,4-dimethylhex-2-enal (10bf) Method A. A mixture of acetal 1,1-dimethoxy-2-methylpent-
2-ene 5’b (35.0 g, 243 mmol), 6f (30.6 g , 243 mmol) and triethanolamine-H3PO4 (0.5 g) was heated at 160 °C for
6 h to give 10bf (16.1 g, 32%). Method B. A solution of aldehyde 5b (31.1 g, 317 mmol), allyl alcohol 6f (20.0 g,
158 mmol) and triethylamine hydrochloride (0.98 g) in xylene (100 mL) was heated at 140 °C for 16 h to give
1
10bf (15.6 g, 44%, purity 92%, E/Z = 91: 8, b.p.: 124°C/ 0.11mbar, colorless oil). H NMR (300 MHz, CDCl3):
9.37 (s, 1H), 6.26 (dd, J = 9.9, 1.1 Hz, 1H), 5.00 (t, J = 7.5 Hz, 1H), 2.81-2.59 (m, 1H), 2.22-1.94 (m, 6H), 1.72 (d,
J = 1.1 Hz, 3H, Me), 1.57-1.36 (m, 6H), 1.06 (d, J = 6.7 Hz, 3H, Me) ppm. 13C NMR (75 MHz, CDCl3): Major
isomer (2E): 195.6 (d), 160.2 (d), 141.6 (s), 137.9 (s), 117.9 (d), 37.2 (t), 34.4 (d), 33.8 (t), 28.8 (t), 28.6 (t), 27.8
(t), 26.8 (t), 19.4 (q), 9.4 (q) ppm. IR (neat): 2925, 2853, 1687, 1639, 1447, 1244, 1017, 818 cm-1. GC/MS (EI):
m/z (%): 206 (6) [M+], 188 (1), 164 (1), 148 (1), 109 (68), 98 (100), 91 (6), 81 (11), 67 (85). HRMS (EI): m/z [M+],
calcd for C14H22O: 206.1665; found: 206.1679. Odor description: chemical, floral, weak.
(2E)-6-Ethyl-2,4-dimethylocta-2,6-dienal (10bg) Method A. A mixture of acetal 1,1-dimethoxy-2-methylpent-2-
ene 5’b (40.9 g, purity 85%, 241 mmol), alcohol 6g (21.9 g, 219 mmol) and triethanolamine-H3PO4 (0.3 g) was
heated at 160 °C for 8 h to give 10bg (31.4 g, yield 79%). Method B. A solution of aldehyde 5b (35.0 g, 357
mmol), alcohol 6g (23.8 g, 238 mmol) and triethylamine hydrochloride (1.0 g) in xylene (50 mL) was heated at
140 °C for 15 h to give 10bg (23.0 g, 54%, 6E/6Z = 82:18, b.p. 126°C/0.1mbar, colorless oil). 1H NMR (300 MHz,
CDCl3): 9.35/9.34 (2s, 1H), 6.36-6.16 (m, 1H), 5.31-5.05 (m, 1H), 2.96-2.71 (m, 1H), 2.23-1.89 (m, 4H), 1.73/1.71
(2s, 3H, Me), 1.63-1.49 (m, 3H, Me), 1.09-0.85 (m, 6H, 2Me) ppm. 13C NMR (75 MHz, CDCl3): Major isomer:
195.6 (d), 160.6 (d), 138.9 (s), 137.7 (s), 120.5 (d), 43.4 (t), 32.0 (d), 22.6 (t), 19.5 (q), 12.9 (q), 12.7 (q), 9.2 (q)
ppm. IR (neat): 2965, 1686, 1639, 1456, 1377, 1242, 1017, 828, 674 cm-1. GC/MS (EI): m/z (%): 180 (7) [M+],
165 (4), 151 (67), 123 (29), 109 (7), 98 (66), 83 (34), 69 (15), 55 (100). HRMS (EI): m/z [M+], calcd for C12H20O:
180.1509; found: 180.1517. Odor description: aldehydic, orris, citrus, tetrahydrocitral.
2,4,7,11-Tetramethyldodeca-2,6,10-trienal (10bh) Method A. A mixture of acetal 1,1-dimethoxy-2-methylpent-2-
ene 5’b (65.0 g, purity 95%, 428 mmol), alcohol 6h (62.9 g, 408 mmol) and triethanolamine-H3PO4 (0.4 g) was
heated at 130°C for 8 h to give 10bh (65.0 g, 68%). Alternatively, prepared according to general procedure
Method B, a solution of aldehyde 5b (70.0 g, 713 mmol), alcohol 6h (100 g, 648 mmol) and triethylamine
hydrochloride (3.57 g) in xylene (100 mL) was heated at 140 °C for 15 h to give 10bh (116 g, 76%, 6E/6Z = 77:23,
b.p. 108°C/0.05mbar, colorless oil). 1H NMR (300 MHz, CDCl3): 9.37 (s, 1H), 6.27 (dd, J = 9.9, 1.2 Hz, 1H), 5.20-
4.98 (m, 2H), 2.82-2.61 (m, 1H), 2.21-1.92 (m, 1H), 1.73 (d, J = 1.2 Hz, 3H, Me), 1.66 (brs, 6H, 2Me), 1.59 (brs,
3H, Me), 1.06 (d, J = 6.7 Hz, 3H, Me) ppm. 13C NMR (75 MHz, CDCl3): Major isomer (6E): 195.6 (d), 160.1 (d),
137.9 (s), 137.2 (s), 131.7 (s), 124.1 (d), 121.9 (d), 34.6 (t), 34.2 (d), 32.0 (t), 26.5 (t), 25.7 (q), 23.4 (q), 19.4 (q),
17.6 (q), 9.3 (q) ppm. IR (neat): 2965, 2927, 1687, 1639, 1452, 1377, 1018, 827, 676 cm-1. GC/MS (EI): m/z (%):
234 (2) [M+], 219 (2), 179 (2), 163 (3), 137 (19), 121 (4), 109 (6), 98 (66), 81 (69), 69 (100), 55 (11). HRMS (EI):
m/z [M+], calcd for C16H26O: 234.1978; found: 234.1987. Odor description: nearly odorless.
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(E)-2,7-Dimethylocta-2,6-dienal (10ca). Method A. A mixture of acetal 1,1-dimethoxy-2-methylpent-2-ene 5’c
(12.3 g, 95 mmol), 6a (8.16 g, 95 mmol) and triethanolamine-H3PO4 (0.1 g) was heated at 160°C for 4 h to give
10ca. (9.3 g, 64%, b.p. 68°C/0.3mbar, colorless oil). 1H NMR (300 MHz, CDCl3): 9.40 (s, 1H), 6.50 (t, J = 6.8 Hz,
1H), 5.13 (t, J = 7.1 Hz, 1H), 2.45-2.33 (m,1H), 2.27-2.13 (m,1H), 1.75 (s, 3H, Me), 1.71 (s, 3H, Me), 1.62 (s, 3H,
Me) ppm. 13C NMR (75 MHz, CDCl3): 195.3 (d), 154.4 (d), 139.5 (s), 133.1 (s), 122.8 (d), 29.2 (t), 26.8 (t), 25.7
(q), 17.7 (q), 9.2 (q) ppm. IR (neat): 2918, 1686, 1644, 1444, 1378, 1251, 1082, 830 cm-1. GC/MS (EI): m/z (%):
152 (3) [M+], 137 (2), 123 (2), 109 (2), 94 (8), 84 (54), 69 (100), 53 (9). HRMS (EI): m/z [M+], calcd for C10H16O:
152.1196; found: 152.1198. Odor description: citrus, fatty.
(E)-2,4-Diethyl-7-methylocta-2,6-dienal (10da) Method A. A mixture of acetal 1,1-dimethoxy-2-methylpent-2-
ene 5’d (34.2 g, 199 mmol), alcohol 6a (17.1 g, 199 mmol) and triethanolamine-H3PO4 was heated at 160°C for 8
h to give 10da (27.9 g, 72%). Method B. A solution of aldehyde 5d (25.0 g, 200 mmol), alcohol 6a (20.6 g, 240
mmol) and triethylamine hydrochloride (1.37 g) in xylene (100 mL) was heated at 140 °C for 15 h to give 10da.
(27.9 g, yield 71%, b.p. 121°C/ 0.07mbar, E/Z = 98:2, colorless oil). 1H NMR (300 MHz, CDCl3): 9.34 (s, 1H), 6.13
(d, J = 10.6 Hz, 1H), 5.04 (t, J = 7.3 Hz, 1H), 2.60-2.41 (m, 1H), 2.30-2.08 (m, 3H), 2.07-1.90 (m, 1H), 1.70-1.48
(m, 7H), 1.41-1.20 (m, 1H), 0.94 (t, J = 7.5 Hz, 3H, Me), 0.84 (t, J = 7.5 Hz, 3H, Me) ppm. 13C NMR (75 MHz,
CDCl3): 195.2 (d), 159.0 (d), 145.1 (s), 133.2 (s), 121.4 (d), 41.3 (d), 33.1 (t), 27.4 (t), 25.7 (q), 17.8 (q), 17.6 (t),
13.4 (q), 11.9 (q) ppm. IR (neat): 2965, 2931, 1686, 1643, 1455, 1377, 1207, 1057, 980, 805, 770 cm-1. GC/MS
(EI): m/z (%): 194 (4) [M+], 179 (1), 165 (1), 126 (100), 111 (24), 97 (40), 69 (67). HRMS (EI): m/z [M+], calcd for
C13H22O: 194.1665; found: 194.1670. Odor description: floral, rose, fruity, metallic, lavender, geranyl acetate,
sweet.
(2E,6E)-2,4-Dimethylnona-2,6-dienal (10bi). Method B. A solution of aldehyde 5b (29.5 g, 301 mmol), allyl
alcohol 6i (27.0 g, 301 mmol) and triethylamine hydrochloride (2.07 g) in xylene (50 mL) was heated at 140 °C for
16 h to give 10bi. (36.8 g, 67%, purity 91%, 6E/6Z = 99:1, b.p. 83°C/0.053mbar, colorless oil). 1H NMR (300 MHz,
CDCl3): 9.39 (s, 1H), 6.28 (d, J = 9.8 Hz, 1H), 5.49 (dt, J = 15.6 Hz, 5.7 Hz, 1H), 5.31 (dt, J = 15.6 Hz, 5.7 Hz,
1H), 2.83-2.64 (m, 1H), 2.19-1.91 (m, 4H), 1.74 (s, 3H, Me), 1.07 (d, J = 6.7 Hz, 3H, Me), 0.95 (t, J = 7.5 Hz, 3H,
Me) ppm. 13C NMR (75 MHz, CDCl3): 195.6 (d), 159.9 (d), 137.9 (s), 134.6 (d), 125.8 (d), 39.4 (t), 33.9 (d), 25.5
(t), 19.3 (q), 13.8 (q), 9.4 (q) ppm. IR (neat): 2963, 1686, 1639, 1456, 1235, 1018, 967, 825, 675 cm-1. GC/MS
(EI): m/z (%): 166 (4) [M+], 151 (1), 137 (7), 123 (1), 109 (1), 98 (100), 91 (3), 83 (20), 69 (53). HRMS (EI): m/z
[M+], calcd for C11H18O: 166.1352; found: 166.1362. Odor description: citrus, strong.
2,5-Dimethyl-4-methylene-2-(prop-1-en-1-yl)hexanal (9bj). Method B. A solution of aldehyde 5b (30.6 g, 312
mmol), allyl alcohol 6j (24 g, 240 mmol) and triethylamine hydrochloride (0.5 g) in toluene (150 mL) was heated
1
at 115 °C for 15 h to give 9bj (21.1 g, 49%, 95°C/0.12mbar, colorless oil). H NMR (300 MHz, CDCl3): 9.40 (s,
1H), 5.61-5.35 (m, 2H), 4.87 (s, 1H), 4.67 (s, 1H), 2.46 (d, J = 14.4 Hz, 1H), 2.31 (d, J = 14.4 Hz, 1H), 2.14-1.97
(m, 1H), 1.72 (d, J = 6.1 Hz, 3H, Me), 1.14 (s, 3H, Me), 1.01(s, 3H, Me), 0.99 (s, 3H, Me) ppm. 13C NMR (75 MHz,
CDCl3): 202.7 (d), 151.5 (s), 131.8 (d), 127.4 (d), 110.7 (t), 52.0 (s), 41.4 (t), 34.1 (d), 21.8 (q), 21.6 (q), 18.6 (q),
18.4 (q) ppm. IR (neat): 2963, 1725, 1639, 1452, 1462, 1378, 1180, 1041, 971, 894 cm-1. GC/MS (EI): m/z (%):
180 (1) [M+], 165 (9), 151 (7), 137 (24), 125 (52), 109 (48), 95 (100), 81 (27), 67 (58), 55 (51), 41 (74). HRMS
(EI): m/z [M+], calcd for C12H20O: 180.1509; found: 180.1510. Odor description: green, floral.
(E)-2,4,7-Trimethyl-6-methyleneoct-2-enal (10bj) Method B. A solution of aldehyde 5b (25.0 g, 255 mmol), allyl
alcohol 6j (32.2 g, 306 mmol) and triethylamine hydrochloride (1.68 g) in xylene (50 mL) was heated at 140 °C for
16 h to give 10bj (28.0 g, purity 85%, 52%, E/Z = 92:8, b.p. 112 °C/0.12 mbar, colorless oil). 1H NMR (300 MHz,
CDCl3): 9.36 (s, 1H), 6.24 (dd, J = 9.8, 1.1 Hz, 1H), 4.77 (s, 1H), 4.63 (s, 1H), 3.02-2.78 (m, 1H), 2.28-2.03 (m,
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3H), 1.73 (d, J = 1.1 Hz, 3H, Me), 1.10-0.94 (m, 9H, 3Me) ppm. 13C NMR (75 MHz, CDCl3): 195.5 (d), 160.2 (d),
152.9 (s), 137.8 (s), 108.7 (t), 41.7 (t), 33.4 (d), 32.1 (d), 21.8 (q), 21.7 (q), 19.6 (q), 9.3 (q) ppm. IR (neat): 2962,
1685, 1640, 1455, 1247, 1018, 892, 827 cm-1. GC/MS (EI): m/z (%): 180 (2) [M+], 165 (11), 154 (4), 137 (67), 123
(45), 109 (61), 95 (41), 81 (24), 69 (65), 55 (77), 41 (100). HRMS (EI): m/z [M+], calcd for C12H20O: 180.1509;
found: 180.1517. Odor description: muguet, floral woody.
2,4,6-Trimethylnona-2,6-dienal (10bk). Method B. A solution of aldehyde 5b (52.9 g, 539 mmol), allyl alcohol 6k
(50.1 g, purity 90%, 449 mmol) and triethylamine hydrochloride (2.47 g) in xylene (100 mL) was heated at 140 °C
for 16 h to give 10bk (48.1 g, 59%, 6E/6Z = 96:4, b.p. 118°C/0.12 mbar, colorless oil). 1H NMR (300 MHz, CDCl3):
9.37 (s, 1H), 6.25 (d, J = 9.8 Hz, 1H), 5.13 (t, J = 7.1 Hz, 1H), 2.98-2.78 (m, 1H), 2.16-1.89 (m, 4H), 1.74 (s, 3H,
Me), 1.58 (s, 3H, Me), 1.03 (d, J = 6.7 Hz, 3H, Me), 0.91 (t, J = 7.5 Hz, 3H, Me) ppm. 13C NMR (75 MHz, CDCl3):
195.6 (d), 160.4 (d), 137.7 (s), 131.4 (s), 129.2 (d), 46.6 (t), 31.9 (d), 21.1 (t), 19.4 (q), 15.8 (q), 14.2 (q), 9.2 (q)
ppm. IR (neat): 2962, 1686, 1640, 1455, 1380, 1241, 1015, 838, 675 cm-1. GC/MS (EI): m/z (%): 180 (4) [M+],
165 (4), 151 (15), 137 (8), 123 (6), 109 (4), 98 (43), 83 (38), 69 (14), 55 (100), 41 (38). HRMS (EI): m/z [M+],
calcd for C12H20O: 180.1509; found: 180.1519. Odor description: green, aldehydic, fatty.
2,4-Dimethyl-7-phenylhepta-2,6-dienal (10bl) Method B. A solution of aldehyde 5b (110 g, 1.12 mol), cinnamic
alcohol 6l (100 g, 0.75 mol) and triethylamine hydrochloride (4.62 g) in xylene (150 mL) was heated at 140 °C for
1
16 h to give 10bl (107 g, yield 67%, 2E/2Z = 95:5, b.p. 126°C/ 0.08mbar, colorless oil). H NMR (300 MHz,
CDCl3): 9.40 (s, 1H), 7.40-7.15 (m, 5H), 6.49-6.26 (m, 2H), 6.20-6.04 (m, 1H), 2.97-2.76 (m, 1H), 2.43-2.23 (m,
2H), 1.76 (br s, 3H, Me), 1.12 (d, J = 6.7 Hz, 3H, Me) ppm. 13C NMR (75 MHz, CDCl3): 195.5 (d), 159.1 (d), 138.3
(s), 137.3 (s), 132.1 (d), 128.6 (d), 127.2 (d), 126.0 (d), 39.8 (t), 33.9 (d), 19.5 (q), 9.5 (q) ppm. IR (neat): 2964,
1683, 1639, 1495, 1450, 1019, 965, 742, 692 cm-1. GC/MS (EI): m/z (%): 214 (5) [M+], 199 (1), 186 (1), 152 (1),
141 (2), 128 (3), 117 (100), 102 (2), 91 (12), 77 (3), 65 (3), 51 (2). HRMS (EI): m/z [M+], calcd for C15H18O:
214.1352; found: 214.1357. Odor description: weak woody, floral.
(E)-2,4-Dimethyl-5-(4-(prop-1-en-2-yl)cyclohex-1-en-1-yl)pent-2-enal (10bm). Method B.
A solution of
aldehyde 5b (8.00 g, 82.0 mmol), allyl alcohol 6m (12.4 g, 82.0 mmol) and triethylamine hydrochloride (0.5 g) in
1
xylene (50 mL) was heated at 140 °C for 16 h to give 10bm (7.1 g, yield 37%, colorless oil). H NMR (300 MHz,
CDCl3): 9.38 (s, 1H), 6.25 (d, J = 9.7 Hz, 1H), 5.40 (s, 1H), 4.70 (s, 1H), 2.96-2.74 (m, 1H), 2.17-1.85 (m, 8H),
1.80-1.62 (m, 7H), 1.54-1.32 (m, 1H), 1.04 (d, J = 6.6 Hz, 3H, Me) ppm. 13C NMR (75 MHz, CDCl3): 195.5 (d),
160.3 (d), 149.7 (s), 137.7 (s), 134.7 (s), 123.0 (d), 108.6 (t), 44.7 (t), 40.9 (d), 31.9 (d), 30.7 (t), 28.8 (t), 27.7 (t),
20.8 (q), 19.6 (q), 9.3 (q) ppm. IR (neat): 2920, 1686, 1642, 1453, 1375, 1239, 1017, 885, 827 cm-1. GC/MS (EI):
m/z (%): 232 (23) [M+], 217 (9), 203 (16), 189 (16), 175 (8), 161 (8), 147 (5), 135 (17), 119 (17), 107 (43), 93
(100), 79 (68), 67 (36), 55 (30), 41 (52). HRMS (EI): m/z [M+], calcd for C16H24O: 232.1822; found: 232.1831.
Odor description: woody, violet, orris, oily, mild.
(2E)-2,4,5,7-Tetramethylocta-2,6-dienal (10bn) Method B. A solution of aldehyde 5b (10.0 g, 102 mmol), allyl
alcohol 6n (10.2 g, 102 mmol) and triethylamine hydrochloride (0.5 g) in xylene (50 mL) was heated at 140 °C for
16 h to give 10bn. (3.12 g, yield 17%, d.r. = 11:89, colorless oil). 1H NMR (300 MHz, CDCl3): 9.38 (s, 1H), 6.31 (d,
J = 9.7 Hz, 1H), 4.92 (d, J = 9.3 Hz, 1H), 2.68-2.52 (m, 1H), 2.51-2.34 (m, 1H), 1.74 (br s, 3H, Me), 1.67 (br s, 3H,
Me), 1.61 (br s, 3H, Me), 1.03 (d, J = 6.7 Hz, 3H, Me), 0.95 (d, J = 6.7 Hz, 3H, Me) ppm. 13C NMR (75 MHz,
CDCl3): 195.6 (d), 159.1 (d), 138.2 (s), 131.6 (s), 127.7 (d), 39.4 (d), 37.8 (d), 25.8 (d), 18.7 (q), 18.1 (q), 17.3 (q),
9.4 (q) ppm. IR (neat): 2964, 2361, 1687, 1639, 1453, 1378, 1219, 1011, 829 cm-1. GC/MS (EI): m/z (%): 180 (1)
[M+], 109 (1), 98 (32), 83 (100), 67 (7), 55 (42). HRMS (EI): m/z [M+], calcd for C12H20O: 180.1509; found:
180.1513. Odor description: floral, citrus, green.
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2-Methyl-2-(prop-1-en-1-yl)hept-4-enal (9bo) Method B. A solution of aldehyde 5b (57.0 g, 581 mmol), allyl
alcohol 6o (20.0 g, 232 mmol) and triethylamine hydrochloride (4 g) in xylene (40 mL) was heated at 140 °C for
1
20 h to give 9bo. (17.1 g, 44%, 103°C/ 0.15mbar, colorless oil). H NMR (300 MHz, CDCl3): 9.35 (s, 1H), 5.60-
5.18 (m, 4H), 2.37-2.17 (m, 2H), 2.08-1.92 (m, 2H), 1.73 (dd, J = 6.3, 0.8 Hz, 3H, Me), 1.11 (s, 3H, Me), 0.95 (t,
J = 7.5 Hz, 3H, Me) ppm. 13C NMR (75 MHz, CDCl3): 202.9 (d), 136.2 (d), 131.4 (d), 127.9 (d), 123.2 (d), 51.8 (s),
39.0 (t), 25.6 (t), 18.4 (q), 13.8 (q) ppm. IR (neat): 2964, 1726, 1454, 1376, 1181, 967, 781 cm-1. GC/MS (EI): m/z
(%):166 (1) [M+], 151 (2), 109 (6), 98 (100), 81 (24), 69 (44), 53 (19). HRMS (EI): m/z [M+], calcd for C11H18O:
166.1352; found: 166.1361. Odor description: green, fruity, resinous, agrestic, slightly chemical.
(2E)-5-Ethyl-2,4-dimethylhepta-2,6-dienal (10bo) Aldehyde 9bo (20.0 g, 120 mmol) was heated at 180 °C for 1
h under Ar to give 10bo (15.0 g, yield 75%, d.r. = 38:62, colorless oil). 1H NMR (300 MHz, CDCl3): 9.41/9.38 (2s,
1H), 6.37-6.26 (m, 1H), 5.62-5.43 (m, 1H), 5.17-4.96 (m, 2H), 2.85-2.54 (m, 1H), 2.05-1.80 (m, 1H), 1.75 (br s,
3H, Me), 1.58-1.38 (m, 1H), 1.35-1.12 (m, 1H), 1.06/1.01 (2d, J = 6.8 Hz, 3H, Me), 0.86/0.84 (2t, J = 6.8 Hz, 3H,
Me) ppm. 13C NMR (75 MHz, CDCl3): 195.5/195.4 (2d), 159.3/158.2 (2d), 139.6/138.9 (2d), 138.4/138.2 (2s),
116.9/116.8 (2t), 51.6/51.5 (2d), 37.3/37.1 (2d), 25.3/25.1 (2t), 17.8/17.0 (2q), 11.8 (q), 9.5/9.4 (2q) ppm. IR
(neat): 2963, 1686, 1640, 1455, 1378, 996, 914 cm-1. GC/MS (EI): m/z (%): 166 (1) [M+], 151 (1), 137 (8), 109 (4),
98 (100), 91 (5), 83 (19), 69 (42). HRMS (EI): m/z [M+], calcd for C11H18O: 166.1352; found: 166.1356. Odor
description: green, woody, citrus.
2,4,5-Trimethylnona-2,6,8-trienal (10bp’) and 2,4-dimethyldeca-2,6,8-trienal (10bp). Method B. A solution of
aldehyde 5b (22.5 g, 229 mmol), allyl alcohol 6p (56.3 g, 573 mmol) and triethylamine hydrochloride (1.0 g) in
xylene (80 mL) was heated at 140 °C for 16 h to give a mixture of 10bp and 10bp’ in a ratio of 35: 65 (19.0 g,
46%, colorless oil). 1H NMR (of the mixture) (300 MHz, CDCl3): 9.40 (s, 1H), 6.39-6.19 (m, 1H), 6.12-5.19 (m, 2H),
5.67-5.50 (m, 2H), 5.49-5.36 (m, 1H), 5.19-4.95 (m, 1H), 2.86-2.52 (m, 1H), 2.39-2.05 (m, 2H), 1.83-1.62 (m, 5H),
1.16-0.92 (m, 6H,) ppm. Major isomer (10bp’) 13C NMR (75 MHz, CDCl3): δ = 195.4 (d), 158.0 (d), 138.6 (s),
136.9 (d), 136.8 (d), 131.2 (d), 115.9 (t), 41.9 (d), 38.8 (d), 17.7 (q), 17.4 (q), 9.5 (q) ppm. GC/MS (EI): m/z (%):
178 (1) [M+], 163 (1), 150 (1), 109 (2), 98 (27), 91 (4), 81 (100), 65 (4), 53 (11). HRMS (EI): m/z [M+], calcd for
C12H18O, 178.1352; found: 178.1364. Minor isomer (10bp) 13C NMR (75 MHz, CDCl3): δ = 195.5 (d), 159.4 (d),
138.1 (s), 132.6 (d), 131.2 (d), 128.0 (d), 127.9 (d), 39.4 (t), 33.9 (d), 19.4 (q), 18.0 (q), 9.4 (q) ppm. GC/MS (EI):
m/z (%): 178 (3) [M+], 163 (1), 150 (1), 136 (1), 115 (2), 98 (25), 91 (4), 81 (100), 65 (5), 53 (9). IR (neat): 2965,
1685, 1638, 1453, 1377, 989, 899, 827 cm-1. HRMS (EI): m/z [M+], calcd for C12H18O, 178.1352; found: 178.1360.
Odor description: aldehydic, fatty, metalic, green, rooty, carrot.
(2E)-2,7-Dimethyl-6-methyleneoct-2-enal (10cj) Method B. A solution of tiglic aldehyde 5c (29.8 g, 297 mmol),
allyl alcohol 6j (25.0 g, 297 mmol) and triethylamine hydrochloride (1.0 g) in xylene (80 mL) was heated at 140 °C
for 15 h to give 10cj (20.0g, 40%, colorless oil). 1H NMR (300 MHz, CDCl3): 9.40 (s, 1H), 6.50 (td, J = 7.2 Hz, 1.2
Hz, 1H), 4.83 (s, 1H), 4.71 (bs, 1H), 2.51 (q, J = 7.5 Hz, 2H), 2.33-2.19 (m, 3H), 1.76 (s, 3H, Me), 1.06 (s, 3H,
Me), 1.04 (s, 3H, Me) ppm. 13C NMR (75 MHz, CDCl3): 195.3 (d), 154.4 (d), 154.2 (s), 139.4 (s), 107.3 (t), 33.8
(d), 32.6 (t), 27.4 (t), 21.8 (q), 9.2 (q) ppm. IR (neat): 2962, 1686, 1641, 1463, 1241, 1018, 889 cm-1. GC/MS (EI):
m/z (%): 166 (1) [M+], 151 (27), 133 (8), 123 (100), 109 (72), 95 (56), 81 (32), 67 (36), 55 (93). HRMS (EI): m/z
[M+], calcd for C11H18O: 166.1352; found: 166.1362. Odor description: citrus, lemon, woody, spicy, fatty and
metallic.
(2E)-2,6-Dimethylnona-2,6-dienal (10ck). Method B. A solution of tiglic aldehyde 5c (18.9 g, 223 mmol), allyl
alcohol 6k (23.5 g, 225 mmol) and triethylamine hydrochloride (1.55 g) in xylene (100 mL) was heated at 140 °C
for 21 h to give 10ck (15.1 g, 40%, b.p. 128°C/0.18mbar, colorless oil). 1H NMR (300 MHz, CDCl3): 9.33 (s, 1H),
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6.43 (t, J = 7.1 Hz, 1H), 5.12 (t, J = 7.1 Hz, 1H), 2.41 (td, J = 7.4 Hz, 7.1 Hz, 1H), 2.11 (t, J = 7.4 Hz, 1H), 1.95
(dq, J = 7.3 Hz, 7.1 Hz, 1H), 1.69 (s, 3H, Me), 1.57 (s, 3H, Me), 0.88 (d, J = 7.5 Hz, 3H, Me) ppm. 13C NMR (75
MHz, CDCl3): 195.1 (d), 154.4 (d), 139.3 (s), 132.6 (s), 127.7 (d), 37.9 (t), 27.4 (t), 21.1 (t), 15.6 (q), 14.2 (q), 9.1
(q) ppm. IR (neat): 2962, 1686, 1645, 1453, 1241, 1011, 850 cm-1. GC/MS (EI): m/z (%):166 (6) [M+], 151 (16),
137 (43), 123 (7), 109 (17), 95 (7), 83 (36), 67 (11), 55 (100). HRMS (EI): m/z [M+], calcd for C11H18O: 166.1352;
found: 166.1364. Odor description: citrus, aldehydic, green, strong.
3-(3-Methylbut-2-en-1-yl)cyclohex-1-enecarbaldehyde (10ea). Method B.
A solution of cyclohexene
carbaldehyde 5e (26.0 g, 236 mmol), allyl alcohol 6a (24.4 g, 283 mmol) and triethylamine hydrochloride (1.30 g)
in xylene (50 mL) was heated at 140 °C for 16 h to give 10ea (12.2 g, yield 30%, b.p. 121°C/0.05mbar, colorless
oil). 1H NMR (300 MHz, CDCl3): 9.40 (s, 1H), 6.66 (s, 1H), 5.16 (t, J = 7.3 Hz, 1H), 2.44-2.19 (m, 2H), 2.18-1.98
(m, 3H), 1.91-1.75 (m, 2H), 1.72 (s, 3H, Me), 1.61 (s, 3H, Me), 1.56-1.39 (m, 1H), 1.36-1.18 (m, 1H) ppm. 13C
NMR (75 MHz, CDCl3): 194.6 (d), 155.2 (d), 141.2 (s), 133.7 (s), 121.6 (d), 37.4 (d), 33.4 (t), 28.5 (t), 25.8 (q),
21.5 (t), 20.4 (t), 17.9 (q) ppm. IR (neat): 2929, 1682, 1638, 1449, 1337, 1178, 1058, 756, 699 cm-1. GC/MS (EI):
m/z (%): 178 (3) [M+], 163 (1), 128 (1), 110 (100), 95 (14), 79 (19), 69 (62), 53 (7). HRMS (EI): m/z [M+], calcd for
C12H18O: 178.1352; found: 178.1357. Odor description: citral rubbery, herbaceous, tetrahydro citral.
3-(2,3-Dimethylbut-2-en-1-yl)cyclohex-1-enecarbaldehyde (10eq). Method B. A solution of aldehyde 5e (6.00
g, 54.5 mmol), allyl alcohol 6q (3.64 g, 36.3 mmol) and triethylamine hydrochloride (0.5 g) in xylene (50 mL) was
1
heated at 140 °C for 16 h to give 10eq (1.98 g, 29%, bp. 142°C/0.11mbar, colorless oil). H NMR (300 MHz,
CDCl3): 9.39 (s, 1H), 6.62 (s, 1H), 2.55-2.42 (m, 1H), 2.33-2.00 (m, 4H), 1.86-1.73 (m, 2H), 1.68 (bs, 6H, 2Me),
1.64 (s, 3H, Me), 1.60-1.41 (m, 1H), 1.36-1.18 (m, 1H) ppm. 13C NMR (75 MHz, CDCl3): 194.7 (d), 155.6 (d),
140.9 (s), 126.7 (s), 124.8 (s), 39.6 (t), 35.6 (d), 28.6 (t), 21.6 (t), 20.7(1) (q), 20.6(8) (q), 20.4 (t), 18.5 (q) ppm. IR
(neat): 2929, 1683, 1638, 1449, 1375, 1177, 698 cm-1. GC/MS (EI): m/z (%): 192 (10) [M+], 145 (1), 110 (100),
95 (9), 83 (74), 67 (6), 55 (53), 41 (21). HRMS (EI): m/z [M+], calcd for C13H20O: 192.1509; found: 192.1516.
Odor description: citrus, metallic, rosy, citral, rose oxide.
3-(3-Methylbut-2-en-1-yl)-4-(prop-1-en-2-yl)cyclohex-1-enecarbaldehyde (10fa). Method B. A solution of
perilla aldehyde 5f (3.00 g, 19.9 mmol), allyl alcohol 6a (3.44 g, 39.9 mmol) and triethylamine hydrochloride (0.4
1
g) in xylene (50 mL) was heated at 140 °C for 16 h to give 10fa (1.1 g, 23%, colorless oil). H NMR (300 MHz,
CDCl3): 9.41 (s, 1H), 6.69 (s, 1H), 5.23-4.96 (m, 1H), 4.81 (s, 1H), 4.73 (s, 1H), 2.48-2.16 (m, 3H), 2.15-1.86 (m,
3H), 1.83-1.64 (m, 8H), 1.62-1.43 (m, 4H) ppm. 13C NMR (75 MHz, CDCl3): 194.2 (d), 154.6 (d), 147.1 (s), 140.9
(s), 134.0 (s), 121.2 (d), 111.7 (t), 47.2 (d), 40.3 (d), 30.7 (t), 27.2 (t), 25.8 (q), 21.5 (t), 19.3 (q), 17.9 (q) ppm. IR
(neat): 2930, 1684, 1640, 1449, 680 cm-1. GC/MS (EI): m/z (%): 218 (7) [M+], 203 (3), 189 (6), 175 (10), 162 (1),
150 (55), 135 (25), 121 (10), 107 (23), 91 (21), 69 (100), 53 (10), 41 (46). HRMS (EI): m/z [M+], calcd for C15H22O:
218.1665; found: 218.1666. Odor description: weak fruity, floral.
(2E)-4-Ethyl-7-methylocta-2,6-dienal (10ga). Method B. A solution of aldehyde 5g (25.0 g, 257 mmol), allyl
alcohol 6a (23.3 g, 270 mmol) and triethylamine hydrochloride (0.71 g) in xylene (50 mL) was heated at 140 °C
for 16 h to give 10ga. (17.8 g, 42%, E:Z = 96:4, b.p. 72°C/ 0.04 mbar, colorless oil). 1H NMR (300 MHz, CDCl3):
9.47 (d, J = 7.9 Hz, 1H), 6.64 (dd, J = 15.6 Hz, 8.3 Hz, 1H), 6.05 (dd, J = 15.6 Hz, 7.9 Hz, 1H), 2.32-1.95 (m, 3H),
1.66 (br s, 3H, Me), 1.61-1.47 (m, 4H), 1.46-1.28 (m, 1H), 0.85 (t, J = 7.4 Hz, 3H, Me) ppm. 13C NMR (75 MHz,
CDCl3): 194.1 (d), 162.7 (d), 133.4 (s), 132.7 (d), 121.1 (d), 45.0 (d), 32.3 (t), 26.4 (t), 25.7 (q), 17.9 (q), 11.6 (q)
ppm. IR (neat): 2965, 1690, 1634, 1454, 1379, 1123, 1080, 976 cm-1. GC/MS (EI): m/z (%): 166 (4) [M+], 151 (1),
137 (4), 122 (4), 110 (3), 98 (74), 91 (5), 83 (18), 69 (100), 53 (10). HRMS (EI): m/z [M+], calcd for C11H18O:
166.1352; found: 166.1359. Odor description: herbaceous, floral, woody, fruity.
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(2E)-7-Methyl-4-propylocta-2,6-dienal (10ha) Method B. A solution of heptenal 5h (82.2 g, 703 mmol), allyl
alcohol 6a (40.2 g, 466 mmol) and triethylamine hydrochloride (3.21 g) in xylene (100 mL) was heated at 140 °C
1
for 21 h to give 10ha (23.3 g, 28%, b.p. 94°C/0.23mbar, colorless oil). H NMR (300 MHz, CDCl3): 9.48 (d, J =
7.9 Hz, 1H), 6.65 (dd, J = 15.6, 8.7 Hz, 1H), 6.06 (dd, J = 15.6 Hz, 7.9 Hz, 1H), 5.04 (t, J = 6.4 Hz, 1H), 2.45-2.26
(m, 1H), 2.25-1.97 (m, 2H), 1.67 (s, 3H, Me), 1.57 (s, 3H, Me), 1.53-1.16 (m, 4H), 0.88 (t, J = 7.1 Hz, 3H, Me)
ppm. 13C NMR (75 MHz, CDCl3): 194.3 (d), 163.7 (d), 133.5 (s), 132.5 (d), 121.1 (d), 43.2 (d), 35.8 (t), 32.7 (t),
25.8 (q), 20.4 (t), 17.9 (q), 14.1 (q) ppm. IR (neat): 2928, 1690, 1634, 1453, 1378, 1124, 976 cm-1. GC/MS (EI):
m/z (%): 180 (3) [M+], 165 (1), 151 (2), 138 (3), 122 (1), 112 (87), 91 (6), 83 (46), 69 (100), 53 (11). HRMS (EI):
m/z [M+], calcd for C12H20O: 180.1509; found: 180.1517. Odor description: waxy, oily, floral, rosy, orris, violet,
woody, pungent.
2,3,6,7-Tetramethylocta-2,6-dienal (10iq). Method B. A solution of aldehyde 5i (5.00 g, 50.9 mmol), allyl alcohol
6q (6.63 g, 66.2 mmol) and triethylamine hydrochloride (0.3 g) in xylene (50 mL) was heated at 140 °C for 16 h to
give 10iq (2.94 g, 32%, E/Z = 55: 44, b.p. 112°C/0.11mbar, colorless oil). 1H NMR (300 MHz, CDCl3): 10.12/9.94
(2s, 1H), 2.59 (t, J = 7.4 Hz, 1H), 2.35-1.94 (m, 6H), 1.80-1.38 (m, 12H) ppm. 13C NMR (75 MHz, CDCl3):
191.5/190.5 (2d), 158.4/158.3 (2s), 132.8/132.1 (2s), 126.4/126.3 (2s), 125.8/125.4 (2s), 35.9/34.2 (2t), 32.1/31.4
(2t), 22.1/20.6/20.5/20.1/20.0/18.7/18.4/17.5 (8q), 10.9/10.3 (2q) ppm. IR (neat): 2919, 1664, 1629, 1448, 1373,
1298, 1158, 999 cm-1. GC/MS (EI): m/z (%): (2E-isomer): 180 (4) [M+], 165 (3), 137 (2), 122 (12), 109 (4), 98
(47), 83 (100), 67 (9), 55 (61); (2Z-isomer): 180 (17) [M+], 165 (8), 147 (8), 137 (16), 122 (23), 109 (19), 98 (60),
83 (100), 67 (18), 55 (90). HRMS (EI): m/z [M+], calcd for C12H20O: 180.1509; found: 180.1506. Odor description:
citrus, herbaceous, lemon, verbena, geranitrile, citronellyl nitrile-like.
4-(3-Methylbut-2-en-1-yl)cyclopent-2-enone (10ja) Method B. A solution of ketone 5j (10.0 g, 122 mmol), allyl
alcohol 6a (20.9 g, 244 mmol) and triethylamine hydrochloride (0.5 g) in xylene (50 mL) was heated at 140 °C for
16 h to give 10ja (2.2 g, 12%, b.p. 86°C/0.3mbar, colorless oil). An analytical sample was purified by column
1
chromatography followed by bulb-to-bulb distillation. H NMR (300 MHz, CDCl3): 7.64 (dd, J = 5.6, 2.5 Hz, 1H),
6.16 (dd, J = 5.6 Hz, 2.0 Hz, 1H), 5.11 (t, J = 7.2 Hz, 1H), 3.06-2.92 (m, 1H), 2.50 (dd, J = 18.9, 6.3 Hz, 1H),
2.32-2.01 (m, 2H), 2.01 (dd, J = 18.9, 2.1 Hz, 1H), 17.2 (s, 3H, Me), 16.1 (s, 3H, Me) ppm. 13C NMR (75 MHz,
CDCl3): 210.0 (s), 168.3 (d), 134.3 (s), 133.9 (d), 120.6 (d), 41.7 (d), 40.5 (t), 32.7 (t), 25.7 (q), 17.8 (q) ppm. IR
(neat): 2963, 1725, 1639, 1452, 1378, 1180, 971, 895 cm-1. GC/MS (EI): m/z (%): 150 (3) [M+], 135 (2), 122 (1),
107 (3), 93 (5), 82 (100), 69 (93), 53 (20), 41 (56). HRMS (EI): m/z [M+], calcd for C10H14O: 150.1039; found:
150.1042. Odor description: citrus, fatty, ketonic, agrestic, herbaceous.
General Method C for the reduction of Aldehydes 10 to Alcohols 13
2,4,7-Trimethylocta-2,6-dien-1-ol (13ba). A solution of 2,4,7-trimethylocta-2,6-dienal 10ba (20.0 g, 114 mmol) in
THF (20 mL) was added dropwise to a suspension of LiAlH4 (4.80 g, 126 mmol) in THF (100 mL) at 0 °C over 1h.
After stirring at this temperature for 0.5 h, the solution was allowed to warm to room temperature and stirred for
an additional 1 h. After cooling to 0 °C, 5 mL of water, 5 mL of 15% aq. NaOH then 15 mL of water were carefully
added (N,N,3N). The solution was stirred for 1h at room temperature. Precipitates were filtered and the filtrate
was concentrated under reduced pressure. The residue was purified by column chromatography (PE:EA = 5:1 to
2:1) followed by bulb-to-bulb (81°C/0.15mbar) to afford 2,4,7-trimethylocta-2,6-dien-1-ol 13ba (98%, 2E/2Z = 95:5,
colourless oil). 1H NMR (300 MHz, CDCl3): 5.22 (d, J = 9.4 Hz, 1H), 5.09 (t, J = 7.2 Hz, 1H), 3.99 (d, J = 5.4 Hz,
2H), 2.48-2.33 (m, 1H), 2.05-1.90 (m, 2H), 1.69 (s, 3H, Me), 1.66 (s, 3H, Me), 1.59 (s, 3H, Me), 0.95 (d, J = 6.3
Hz, 3H, Me) ppm. 13C NMR (75 MHz, CDCl3): 133.2 (s), 132.4 (d), 132.1 (s), 122.8 (d), 68.9 (t), 35.6 (t), 32.7 (d),
25.8 (q), 20.4 (q), 17.8 (q), 13.8 (q) ppm. IR (neat): 2962, 2916, 2867, 1452, 1377, 1071, 859 cm-1. GC/MS (EI):
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m/z (%): 168 (1) [M+], 150 (1), 137 (2), 99 (20), 82 (7), 69 (24), 55 (9), 43 (100). HRMS (EI): m/z [M+], calcd for
C11H20O: 168.1509; found: 168.1518. Odor description: floral, rosy, fatty, geranium, citrus.
(2E)-2,4-Dimethylocta-2,6-dien-1-ol (13bb). Aldehyde 10bb was reduced according to procedure C to yield
1
13bb (84%, 6E/6Z = 73:27, b.p. 100 °C/0.1mbar, colorless oil). H NMR (300 MHz, CDCl3): 5.55-5.27 (m, 2H),
5.26-5.12 (m, 1H), 3.98 (s, 2H), 2.53-2.31 (m, 1H), 2.13-1.88 (m, 2H), 1.69-1.55 (m, 6H), 1.45 (bs, 1H), 0.95/0.92
(2d, J = 6.8 Hz, 3H, Me) ppm. 13C NMR (75 MHz, CDCl3): Major (6E)- isomer: 133.3 (s), 132.2(8) (d), 129.5 (d),
126.1 (d), 69.0 (t), 40.4 (t), 32.4(4) (d), 20.3 (q), 17.9 (q), 13.9 (q) ppm. Minor (2Z)-isomer: 133.4 (s), 132.2(5) (d),
128.7 (d), 124.7 (d), 69.0 (t), 34.4 (t), 32.4(1) (d), 20.4 (q), 17.9 (q), 12.9 (q) ppm. IR (neat): 2957, 2916, 1452,
1374, 1008, 965, 850 cm-1. GC/MS (EI): m/z (%): 154 (2) [M+], 136 (3), 123 (8), 109 (2), 99 (100), 81 (25), 67 (18),
55 (42). HRMS (EI): m/z [M]+, calcd for C10H18O: 154.1352; found: 154.1364. Odor description: floral, rosy, green,
woody.
(6E)-2,4-Dimethylnona-2,6-dien-1-ol (13bi). Aldehyde 10bi was reduced according procedure C to yield alcohol
1
13bi (88%, 6E/6Z = 99:1, b.p. 105°C/0.08mbar, colorless oil). H NMR (300 MHz, CDCl3): 5.51-5.25 (m, 2H),
5.19 (d, J = 9.4 Hz, 1H), 3.98 (s, 2H), 2.50-2.30 (m, 1H), 2.07-1.87 (m, 4H), 1.65 (bs, 3H, Me), 1.46 (bs, 1H), 0.94
(t, J = 7.4 Hz, 3H, Me), 0.92 (d, J = 6.7 Hz, 3H, Me) ppm. 13C NMR (75 MHz, CDCl3): 133.4 (d), 133.3 (s), 132.3
(d), 127.2 (d), 69.0 (t), 40.3 (t), 32.5 (d), 25.6 (t), 20.3 (q), 13.9(5) (q), 13.8(7) (q) ppm. IR (neat): 2960, 1455,
1373, 1008, 965, 857 cm-1. GC/MS (EI): m/z (%): 168 (1) [M+], 150 (3), 137 (5), 121 (2), 99 (100), 81 (24), 69 (19),
55 (27). HRMS (EI): m/z [M+], calcd for C11H20O: 168.1509; found: 168.1507. Odor description: rosy, slightly
plastic.
2,4,6-Trimethylhepta-2,6-dien-1-ol (13bd). Aldehyde 10bd was reduced according to procedure C to yield
alcohol 13bd (92%, E/Z = 92:8, b.p. 108°C/0.12mbar, colorless oil). 1H NMR (300 MHz, CDCl3): 5.15/5.01 (2dd, J
= 9.3, 0.9 Hz, 1H), 4.69 (s, 1H), 4.62 (s, 1H), 3.94 (d, J = 5.7 Hz, 2H), 2.68-2.47 (m, 1H), 2.01-1.84 (m, 3H), 1.67
(s, 3H, Me), 1.65 (d, J = 0.9 Hz, 3H, Me), 0.90 (d, J = 6.7 Hz, 3H, Me) ppm. 13C NMR (75 MHz, CDCl3): Major
(2E)-isomer: 144.3 (s), 133.3 (s), 132.3 (d), 111.5 (t), 68.8 (t), 45.7 (t), 30.0 (d), 22.3 (q), 20.4 (q), 13.7 (q) ppm.
Minor (2Z)-isomer: 144.7 (s), 134.5 (d), 133.1 (s), 111.7 (t), 61.7 (t), 46.1 (t), 30.6 (d), 22.5 (q), 21.4 (q), 21.3 (q)
ppm. IR (neat): 2963, 1456, 1377, 1019, 967, 890 cm-1. GC/MS (EI): m/z (%): 154 (1) [M+], 136 (7), 121 (7), 99
(18), 81 (10), 69 (6), 55 (10), 43 (100). HRMS (EI): m/z [M]+, calcd for C10H18O: 154.1352; found: 154.1362. Odor
description: fresh, floral, rose, geraniol-like, earthy, mild.
(2E)-2,4,7-Trimethyl-6-methyleneoct-2-en-1-ol (13bj). Aldehyde 10bj was reduced according to procedure C to
yield alcohol 13bj (93%, b.p. 123°C/0.12mbar, colorless oil). 1H NMR (300 MHz, CDCl3): 5.18 (dd, J = 9.3Hz, 1.2
Hz, 1H), 4.75 (s, 1H), 4.64 (d, J = 1.2 Hz,1H), 3.97 (s, 2H), 2.68-2.49 (m, 1H), 2.18 (sept, J = 6.7 Hz, 1H), 2.08-
1.88 (m, 2H), 1.66 (d, J = 1.2 Hz, 3H, Me), 1.45 (bs, 1H), 1.06-0.96 (m, 6H, 2Me), 0.92 (d, J = 6.6 Hz, 3H, Me)
ppm. 13C NMR (75 MHz, CDCl3): 154.1 (s), 133.1 (s), 132.8 (d), 107.9 (t), 69.0 (t), 42.7 (t), 33.3 (d), 30.5 (d), 21.9
(q), 21.8 (q), 20.6 (q), 13.8 (q) ppm. IR (neat): 2960, 1641, 1454, 1377, 1070, 1008, 890 cm-1. GC/MS (EI): m/z
(%): 182 (1) [M+], 164 (2), 149 (24), 139 (59), 121 (100), 107 (23), 99 (68), 81 (68), 69 (60), 55 (67). HRMS (EI):
m/z [M+], calcd for C12H22O: 182.1665; found: 182.1662. Odor description: fruity, floral, rosy, oily, very weak.
(2E)-5-Ethyl-2,4-dimethylhepta-2,6-dien-1-ol (13bo). Aldehyde 10bo was reduced according to procedure C to
yield 13bo (74%, d.r. = 38:62, b.p. 116°C/0.15mbar, colorless oil). 1H NMR (300 MHz, CDCl3): 5.64-5.39 (m, 1H),
5.27-5.15 (m, 1H), 5.09-4.87 (m, 2H), 3.99/3.98 (2s, 2H), 2.53-2.19 (m, 1H), 1.89-1.73 (m, 1H), 1.66 (s, 3H, Me),
1.56-1.33 (m, 2H), 1.31-0.99 (m, 1H), 0.96-0.74 (m, 6H) ppm. 13C NMR (75 MHz, CDCl3): 141.1/140.1 (2d),
133.9/133.6 (2s), 131.5/129.9 (2d), 115.7 (t), 69.1/69.0 (2t), 52.2/52.1 (2d), 35.8/35.5 (2d), 25.0/24.9 (2t),
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18.9/18.3 (2q), 14.0/13.9 (2q), 12.0/11.9 (2q) ppm. IR (neat): 2960, 1454, 1377, 1066, 998, 910 cm-1. GC/MS (EI):
m/z (%): 168 (1) [M+], 150 (2), 137 (5), 121 (2), 107 (4), 99 (100), 91 (11), 81 (25), 67 (22), 55 (27). HRMS (EI):
m/z [M+], calcd for C11H20O: 168.1509; found: 168.1510. Odor description: floral, rosy, citrus, weak.
(2E)-2,4-Diethyl-7-methylocta-2,6-dien-1-ol (13da). Aldehyde 10da was reduced according to the procedure C
to yield 13da (85%, b.p. 125°C/0.12mbar, colorless oil). 1H NMR (300 MHz, CDCl3): 5.08 (m, 2H), 4.02 (d, J = 5.6
Hz, 2H), 2.28-1.96 (m, 4H), 1.94-1.79 (m, 1H), 1.66 (s, 3H, Me), 1.56 (s, 3H, Me), 1.54-1.37 (m, 2H), 1.24-1.05
(m, 1H), 0.97 (t, J = 7.6 Hz, 3H, Me), 0.81 (t, J = 7.4 Hz, 3H, Me) ppm. 13C NMR (75 MHz, CDCl3): 140.4 (s),
131.9 (s), 131.0 (d), 122.9 (d), 66.8 (t), 39.6 (d), 33.9 (t), 27.9 (t), 25.7 (q), 21.3 (t), 17.8 (q), 13.3 (q), 11.9 (q)
ppm. IR (neat): 2964, 2928, 1454, 1376, 1083, 876, 802 cm-1. GC/MS (EI): m/z (%): 196 (1) [M+], 178 (1), 165 (1),
127 (22), 109 (11), 95 (4), 69 (16), 57 (100), 41 (22). HRMS (EI): m/z [M+], calcd for C13H24O: 196.1822; found:
196.1832. Odor description: weak, floral.
(3-(3-Methylbut-2-en-1-yl)cyclohex-1-en-1-yl)methanol (13ea). Aldehyde 10ea according to the procedure C to
yield alcohol 13ea (72%, b.p. 150°C/0.13mbar, colorless oil). 1H NMR (300 MHz, CDCl3): 5.56 (s, 1H), 5.14 (t, J =
7.2 Hz, 1H), 3.98 (s, 2H), 2.17-1.86 (m, 5H), 1.82-1.67 (m, 5H), 1.59 (s, 3H, Me), 1.56-1.44 (m, 2H), 1.27-1.08
(m, 1H) ppm. 13C NMR (75 MHz, CDCl3): 137.4 (s), 132.5 (s), 127.6 (d), 122.9 (d), 67.6 (t), 35.9 (d), 34.6 (t), 28.8
(t), 25.9 (t), 25.8 (q), 21.5 (t), 17.9 (q) ppm. IR (neat): 2922, 1447, 1376, 1008, 839 cm-1. GC/MS (EI): m/z (%):
180 (2) [M+], 162 (3), 149 (1), 121 (1), 111 (74), 93 (100), 77 (28), 67 (37), 55 (23). HRMS (EI): m/z [M+], calcd for
C12H20O: 180.1509; found: 180.1517. Odor description: floral, fresh, rosy, citral, verbena, peony, magnolia.
(3-(2,3-Dimethylbut-2-en-1-yl)cyclohex-1-en-1-yl)methanol (13eq). Aldehyde 10eq was reduced according to
the procedure C to yield alcohol 13eq (93%, b.p. 147°C/0.1mbar, colorless oil). 1H NMR (300 MHz, CDCl3): 5.53
(s, 1H), 3.99/3.97 (2s, 2H), 2.23 (brs, 1H), 2.09-1.94 (m, 4H), 1.85-1.61 (m, 11H), 1.60-1.42 (m, 1H), 1.37 (t, J =
5.2 Hz, 1H), 1.25-1.07 (m, 1H) ppm. 13C NMR (75 MHz, CDCl3): 137.1 (s), 127.9 (d), 126.0 (s), 125.5 (s), 76.7 (t),
40.7 (t), 34.1 (d), 28.9 (t), 25.9 (t), 21.5 (t), 20.7 (q), 20.6 (q), 18.6 (q) ppm. IR (neat): 2924, 1447, 1375, 1055,
1009, 841 cm-1. GC/MS (EI): m/z (%): 194 (8) [M+], 176 (6), 163 (5), 139 (2), 119 (2), 110 (70), 93 (100), 83 (48),
67 (40), 55 (55). HRMS (EI): m/z [M+], calcd for C13H22O: 194.1665; found: 194.1673. Odor description: floral,
rosy, sandalwood.
(2E)-7-Methyl-4-propylocta-2,6-dien-1-ol (13ha) Aldehyde 10ha was reduced according to procedure C to yield
1
13ha (91%, b.p. 130°C/0.19mbar, colorless oil). H NMR (300 MHz, CDCl3): 5.70-5.40 (m, 2H), 5.10 (bs, 1H),
4.09 (br s, 2H), 2.15-1.88 (m, 3H), 1.69 (s, 3H, Me), 1.58 (s, 3H, Me), 1.52 (br s, 1H), 1.45-1.13 (m, 4H), 0.87 (t, J
= 6.4 Hz, 3H, Me) ppm. 13C NMR (75 MHz, CDCl3): 137.5 (d), 132.1 (s), 128.5 (d), 122.6 (d), 63.8 (t), 42.5 (d),
36.6 (t), 33.6 (t), 25.8 (q), 20.3 (t), 17.9 (q), 14.2 (q) ppm. IR (neat): 2926, 1452, 1377, 1080, 1004, 970 cm-1.
GC/MS (EI): m/z (%): 182 (2) [M+], 164 (2), 151 (10), 139 (5), 121 (3), 112 (31), 95 (46), 83 (21), 69 (100), 55 (16).
HRMS (EI): m/z [M+], calcd for C12H22O: 182.1665; found: 182.1673. Odor description: floral, rose, waxy, oily,
balsamic, agrestic.
2,3,6,7-Tetramethylocta-2,6-dien-1-ol (13iq). Aldehyde 10iq was reduced according to procedure C to yield
13iq (95%, E/Z = 55:44, b.p. 106°C/0.13mbar, colorless oil). 1H NMR (300 MHz, CDCl3): 4.10 (d, J = 3.8 Hz, 1H),
4.03 (d, J = 4.7 Hz, 1H), 2.23-2.01 (m, 4H), 1.80-1.68 (m, 6H), 1.67-1.58 (m, 9H, 3Me), 1.45-1.27 (m, 1H) ppm.
13C NMR (75 MHz, CDCl3): 133.2/133.1 (2s), 128.4/127.8/127.7/127.5 (4s), 124.9/124.2 (2s), 64.0/63.4 (2t),
33.7/33.5 (2t), 32.8/32.7 (2t), 20.5/20.4 (2q), 20.1/20.0/18.9/18.7/18.5/18.0/16.8/16.0 (6q) ppm. IR (neat): 2962,
1452, 1385, 1006, 848, 749 cm-1. GC/MS (EI): m/z (%): 182 (7) [M+], 164 (3), 149 (9), 139 (8), 121 (20), 107 (12),
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98 (52), 83 (100), 67 (22), 55 (66). HRMS (EI): m/z [M+], calcd for C12H22O, 182.1665; found: 182.1676. Odor
description: floral, fatty, rosy, sandalwood.
General Procedure D for the Cyclopropanation to Compounds 14.
(1-Methyl-2-(5-methylhex-4-en-2-yl)cyclopropyl)-methanol (14ba). A solution of sec-butylchloride (11.0 g, 120
mmol) in THF (40 mL) was added dropwise to a mixture of 2,4,7-trimethylocta-2,6-dien-1-ol 13ba (20 g, 119
mmol) and lithium granules (1.7 g, 240 mmol) in THF (50 mL) at 10-15 °C over 0.5 h. The resulting deep grey
solution was stirred for further 0.5 h at 15 °C. Dibromomethane (59 g, 340 mmol) and tert-butylmagnesium
chloride (340 mmol, 1.7 M in THF) were added separately at the same time over 2 hours at 10°C. The resulting
solution was stirred overnight at room temperature. The reaction solution was poured into icy aqueous HCl
solution (1N, 200 mL) and extracted with MTBE (3 x 100 ml). The combined organic layers were washed with sat.
aq. NaHCO3 (100 ml), and brine (100 ml), dried (MgSO4), filtered, and evaporated under reduced pressure. The
residue was purified by bulb-to-bulb distillation (95°C/0.13mbar) to afford (1-methyl-2-(5-methylhex-4-en-2-
yl)cyclopropyl)methanol 14ba (18.3 g, 72%, purity 85%, 2 main isomers 14ba' and 14ba'' in a ratio of 64 : 36) as
a colourless oil. 14ba' and 14ba'' were separated by silica gel column chromatography.
1
((1S*,2R*)-1-Methyl-2-((S*)-5-methylhex-4-en-2-yl)cyclopropyl)methanol (14ba’). H NMR (300 MHz, CDCl3):
5.16 (t, J = 7.5 Hz, 1H), 3.33 (d, J = 10.8 Hz, 1H), 3.24 (d, J = 10.8 Hz, 1H), 2.12-1.87 (m, 1H), 1.70 (s, 3H, Me),
1.60 (s, 3H, Me), 1.21-1.03 (m, 4H), 0.96 (d, J = 6.4 Hz, 3H, Me), 0.35-0.33 (m, 2H), 0.00-0.07 (m, 1H) ppm. 13
C
NMR (75 MHz, CDCl3): 131.9 (s), 123.3 (d), 72.7 (t), 36.1 (t), 33.7 (d), 29.3 (d), 25.8 (q), 23.2 (s), 20.2 (q), 17.8
(q), 15.9 (q), 15.6 (t) ppm. IR (neat): 2964, 2924, 1452, 1376, 1028, 946, 863 cm-1. GC/MS (EI): m/z (%): 182 (1)
[M+], 164 (13), 151 (8), 139 (14), 121 (14), 109 (17), 95 (100), 81 (24), 69 (82), 55 (98). HRMS (EI): m/z [M+],
calcd for C12H22O: 182.1665; found: 182.1671. Odor description: floral, rosy, geraniol.
((1S*,2R*)-1-Methyl-2-((R*)-5-methylhex-4-en-2-yl)cyclopropyl)methanol (14ba’’). 1H NMR (300 MHz, CDCl3):
5.16 (t, J = 7.5 Hz, 1H), 3.33 (d, J = 10.9 Hz, 1H), 3.26 (d, J = 10.9 Hz, 1H), 2.18-2.04 (m, 1H), 2.01-1.87 (m, 1H),
1.68 (s, 3H, Me), 1.59 (s, 3H, Me), 1.13 (s, 3H, Me), 1.08-0.96 (m, 2H), 0.92 (d, J = 6.4 Hz, 3H, Me), 0.57-0.34 (m,
2H), 0.07-0.01 (m, 1H) ppm. 13C NMR (75 MHz, CDCl3): 132.0 (s), 123.0 (d), 72.6 (t), 35.5 (t), 34.6 (d), 29.1 (d),
25.8 (q), 22.3 (s), 20.3 (q), 17.8 (q), 16.4 (t), 15.3 (q) ppm. IR (neat): 2964, 2924, 1450, 1376, 1029, 938 cm-1.
GC/MS (EI): m/z (%): 182 (1) [M+], 164 (8), 149 (7), 139 (23), 121 (32), 109 (7), 95 (68), 81 (17), 69 (47), 55 (100).
HRMS (EI): m/z [M+], calcd for C12H22O: 182.1665; found: 182.1668. Odor description: floral, rosy, phenoxanol,
very nice.
Determination of Relative Configuration for Product 14ba''.
Compound 14ba''-d was subjected to 500 MHz NMR analysis and its configurations were determined by 2D NOE
and C-H COSY. Comparing to 14ba'', the corresponding chemical shifts of H in compound 14ba''-d are
separated well by the assistance of 4-nitrobezoate group.
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1-Methyl-2-(5-methylhex-4-en-2-yl)cyclopropyl)methyl 4-nitrobenzoate (14ba''-d)
A solution of 4-nitrobenzoyl chloride
(1.5 g, 7.95 mmol) in DCM (1 mL) was added to a stirred solution of 14ba’’ (1.4 g, 7.95 mmol) and Et3N (1.2 g,
11.9 mmol) in DCM (10 mL) at 0°C under nitrogen. After stirring at room temperature for 30 min, usual workup
and chromatography over silica-gel (hexane/EA = 5:1) provided 14ba''-d (2.1 g, 79%). White solid, m.p. 74-75 °C.
1H NMR (300 MHz, CDCl3): 8.43-8.12 (m, 4H), 5.17 (t, J = 7.4 Hz, 1H), 4.21 (d, J = 11.1 Hz, 1H), 4.01 (d, J =
11.1 Hz, 1H), 2.27-1.89 (m, 2H), 1.70 (s, 3H, Me), 1.61 (s, 3H, Me), 1.23 (s, 3H, Me), 1.16-1.05 (m, 1H), 0.96 (d,
J = 6.4 Hz, 3H, Me), 0.78-0.55 (m, 2H), 0.26-0.15 (m, 1H) ppm. 13C NMR (75 MHz, CDCl3): 164.8 (s), 150.5 (s),
136.0 (s), 132.2 (s), 130 (d), 123.5 (d), 122.8 (d), 75.4 (t), 35.5 (t), 34.6 (d), 29.6 (d), 25.8 (s), 20.2 (q), 19.1 (q),
17.8 (q), 17.0 (t), 15.9 (q) ppm. IR (neat): 2975, 2360, 1716, 1521, 1340, 1285, 1108, 1048, 967, 878, 840, 719
cm-1. GC/MS (EI): m/z (%): 331 (14) [M+], 281 (7), 253 (5), 232 (2), 207 (47), 191 (4), 164 (12), 150 (60), 135 (5),
121 (35), 104 (18), 95 (100), 81 (22), 69 (40), 55 (26), 41 (38). HRMS (ESI): m/z [M+H+] calcd for C19H25NO4+H+,
332.1856; found: 332.1854.
(2-(Hex-4-en-2-yl)-1-methylcyclopropyl)methanol (14bb) Obtained from 13bb according to procedure D. Yield:
55%, b.p. 94°C/0.1mbar, a mixture of isomers, colorless oil). 1H NMR (300 MHz, CDCl3): 5.53-5.25 (m, 2H), 3.72-
3.22 (m, 2H), 2.17-1.81 (m, 2H), 1.72-1.53 (m, 4H), 1.10 (s, 3H, Me), 1.07-0.84 (m, 4H), 0.51-0.32 (m, 2H), 0.17-
0.01 (m, 1H) ppm. 13C NMR (75 MHz, CDCl3): 130.2/129.7 (2d), 126.5/125.9 (2t), 67.2/67.1 (2t), 41.1/40.5 (2t),
34.6/34.2 (2d), 32.6/32.5 (2d), 23.2/22.2 (2s), 22.9/22.7 (2q), 20.7/20.5 (2q), 17.9 (q), 17.1/15.9 (2t) ppm. IR
(neat): 2957, 1716, 1454, 1376, 1249, 1174, 1031 cm-1. GC/MS (EI): m/z (%): 168 (1) [M+], 150 (6), 135 (5), 121
(6), 107 (6), 95 (97), 81 (24), 69 (100), 55 (26). HRMS (EI): m/z [M+], calcd for C11H20O: 168.1509; found:
168.1521. Odor description: floral, milky, creamy, woody, fatty, sandalwood.
General hydrogenation and reduction procedures for the preparation of compounds 15 and 16.
2,4,7-Trimethyloct-6-enal (15ba). A mixture of Lindlar catalyst (Pd/CaCO3, lead poisoned, 0.40 g), (E)-2,4,7-
trimethylocta-2,6-dienal 10ba (9.00 g, 54.1 mmol) and ethyl acetate (40 mL) was stirred under hydrogen
atmosphere at room temperature overnight. The reaction mixture was filtered through a small pad of silica gel
and the silica gel was washed with MTBE (2 x 30 mL). The combined filtrates were concentrated in vacuo and
the residue was distilled bulb-to-bulb (75°C/0.1mbar) to give 2,4,7-trimethyloct-6-enal 15ba (8.10 g, 88 %, d.r. =
1
1:1, colorless oil). H NMR (300 MHz, CDCl3): 9.58/9.55 (m, 1H ), 5.09 (t, J = 6.8 Hz, 1H), 2.50-2.31 (m, 1H),
2.03-1.73 (m, 2H), 1.68 (s, 3H, Me), 1.64-1.43 (m, 5H), 1.36-1.10 (m, 1H), 1.09-1.01 (m, 3H, Me), 0.90-0.82 (m,
3H, Me) ppm. 13C NMR (75 MHz, CDCl3): 205.4/205.3 (2d), 132.6 (s), 122.6/122.5 (2d), 44.3/44.2 (2d), 37.8/37.2
(2t), 35.6/35.1 (2t), 31.2/31.1 (2d), 25.8 (q), 19.8/19.2 (2q), 17.8 (q), 14.1/13.3 (2q) ppm. IR (neat): 2964, 2915,
1725, 1456, 1377, 1120 cm-1. GC/MS (EI): m/z (%): 168 (11) [M+], 153 (8), 135 (11), 125 (12), 109 (15), 95 (41),
81 (20), 69 (100), 55 (38). HRMS (EI): m/z [M+], calcd for C11H20O: 168.1509; found: 168.1511. Odor description:
citral, lemongrass, verbena, melon.
2,4,7-Trimethyloct-6-en-1-ol (16ba). To a 100 mL three-necked flask equipped with a magnetic stirrer, a
thermometer and a gas inlet, were added 2,4,7-trimethyloct-6-enal 15ba (8.00 g, 47.5 mmol) and methanol (50
ml). The mixture was cooled to 0°C. NaBH4 was added in small portions over 20 minutes. The reaction mixture
was warmed to room temperature and stirred for 30 minutes. Methanol was removed in vacuo. The residue was
diluted with water (60ml) and extracted with ethyl acetate (3 x 30 ml). The combined organic layers were washed
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with brine (10 mL), dried (MgSO4), filtered and concentrated. The crude product was purified by column
chromatography (PE : EA = 5: 1) followed by bulb-to-bulb distillation (95°C/0.13mbar) to give 2,4,7-trimethyloct-6-
en-1-ol 16ba (6.10 g, 75 %, 35.2 mmol) as a colourless liquid. 1H NMR (300 MHz, CDCl3): 5.12 (t, J = 7.0 Hz, 1H),
3.58-3.32 (m, 2H), 2.07-1.65 (m, 5H), 1.64-1.23 (m, 5H), 1.22-1.02 (m, 1H), 1.01-0.79 (m, 6H) ppm. 13C NMR (75
MHz, CDCl3): 132.1/132.0 (2s), 123.3/123.1 (2d), 69.1/68.3 (2t), 40.6/40.3 (2t), 36.3/34.9 (2t), 33.3/33.2 (2d),
30.9/30.8 (2d), 25.8 (q), 20.3/19.2/17.8/17.3/16.3 (5q) ppm. IR (neat): 2958, 2913, 1454, 1377, 1035, 986, 849
cm-1. GC/MS (EI): m/z (%): 170 (4) [M+], 152 (1), 137 (3), 123 (2), 112 (25), 96 (52), 83 (82), 69 (64), 55 (100).
HRMS (EI): m/z [M+], calcd for C12H18O: 170.1671; found: 170.1675. Odor description: fresh citrus, clean,
grapefruit, trendy rhubarb facet.
2,4-Dimethyloct-6-enal (15bb). Obtained from 10bb according to the procedure used for 15ba. Yield: 64%, b.p.
71°C/0.12mbar, 6E/6Z = 73:27, colorless oil). 1H NMR (300 MHz, CDCl3): 9.61-9.53 (m, 1H), 5.59-5.26 (m, 2H),
2.54-2.32 (m, 1H), 2.09-1.41 (m, 8H), 1.36-1.21 (m, 1H), 1.14-1.00 (m, 4H), 0.95-0.79 (m, 3H, Me) ppm. 13C
NMR (75 MHz, CDCl3): Major (6E)-isomer: 205.4/205.3 (2d), 129.1/129.0 (2d), 126.7 (d), 44.2/44.1 (2d),
40.4/39.8 (2t), 37.6/37.0 (2t), 30.7/30.5 (2d), 19.7/19.0 (2q), 17.9 (q), 14.1/13.3 (2q) ppm. Minor (6Z)-isomer:
205.4/205.3 (2d), 128.5/128.4 (2d), 125.1 (d), 44.3/44.2 (2d), 37.7/37.1 (2t), 34.3/33.8 (2t), 30.9/30.8 (2d),
19.7/19.1 (2q), 14.1/13.3 (2q), 12.9 (q) ppm. IR (neat): 2960, 1725, 1458, 1378, 967 cm-1. GC/MS (EI): m/z (%):
154 (3) [M+], 139 (8), 126 (12), 107 (16), 96 (52), 81 (58), 69 (42), 55 (100). HRMS (EI): m/z [M+], calcd for
C10H18O: 154.1352; found: 154.1360. Odor description: fatty, aldehydic, muguet, marine, rosy.
2,4-Dimethyloct-6-en-1-ol (16bb). Obtained from 15bb according to the procedure used for 16ba. Yield: 75%,
1
b.p. 110°C/0.2mbar, 6E/6Z = 73:27, colorless oil. H NMR (300 MHz, CDCl3): 5.56-5.28 (m, 2H), 3.55-3.26 (m,
2H), 2.20-1.41 (m, 8H), 1.39-1.19 (m, 1H), 1.17-0.99 (m, 1H), 0.97-0.74 (m, 7H) ppm. 13C NMR (75 MHz, CDCl3):
Major (6E)-isomer: 129.8/129.6 (2d), 126.1/126.0 (2d), 68.9/68.2 (2t), 41.0/40.4/40.1/39.6 (4t), 33.2/33.1 (2d),
30.4/30.3 (2d), 20.1/19.1/17.9/17.3/16.3 (5q) ppm. Minor (6Z)-isomer: 129.2/129.0 (2d), 124.7/124.6 (2d),
70.0/68.3 (2t), 41.1/40.6/40.5/40.2 (4t), 33.2/33.1 (2d), 30.6/30.5 (2d), 20.2/19.2/17.9/14.1/12.9 (5q) ppm. IR
(neat): 2956, 2915, 1456, 1377, 1034, 965 cm-1. GC/MS (EI): m/z (%): 156 (1) [M+], 138 (1), 125 (7), 109 (9), 98
(30), 83 (64), 67 (20), 55 (100). HRMS (EI): m/z [M+], calcd for C10H20O. 156.1509; found: 156.1515. Odor
description: floral, fatty, woody, muguet, mayol.
2,7-Dimethyloct-6-enal (15ca). Obtained from 10ca according to the procedure used for 15ba. Yield: 98%, p.b.
71°C/0.15mbar, colorless oil. 1H NMR (300 MHz, CDCl3): 9.60 (d, J = 1.8 Hz, 1H), 5.08 (t, J = 6.5 Hz, 1H), 2.42-
2.22 (m, 1H), 2.08-1.90 (m, 2H), 1.78-1.63 (m, 4H), 1.58 (s, 3H, Me), 1.43-1.29 (m, 3H), 1.07 (t, J = 7.0 Hz, 3H,
Me) ppm. 13C NMR (75 MHz, CDCl3): 205.3 (d), 131.9 (s), 124.0 (d), 46.3 (d), 30.1 (t), 27.9 (t), 27.2 (t), 25.7 (q),
17.7 (q), 13.3 (q) ppm. IR (neat): 2928, 1725, 1456, 1377, 925, 834 cm-1. GC/MS (EI): m/z (%): 154 (12) [M+],
139 (8), 121 (17), 111 (17), 95 (22), 81 (57), 69 (100), 55 (37). HRMS (EI): m/z [M+], calcd for C10H18O: 154.1352;
found: 154.1364. Odor description: citronellol, fatty.
2,7-Dimethyloct-6-en-1-ol (16ca). Obtained from 15ca according to the procedure used for 16ba. Yield: 86%,
1
b.p. 115°C/0.15mbar, colorless oil. H NMR (300 MHz, CDCl3): 5.10 (t, J = 6.3 Hz, 1H), 3.56-3.31 (m, 2H), 2.05-
1.84 (m, 2H), 1.68 (s, 3H, Me), 1.59 (s, 3H, Me), 1.45-1.20 (m, 3H), 1.18-1.01 (m, 1H), 0.90 (d, J = 6.7 Hz, 3H,
Me) ppm. 13C NMR (75 MHz, CDCl3): 131.4 (s), 124.7 (d), 68.4 (t), 35.7 (d), 32.8 (t), 28.3 (t), 27.3 (t), 25.7 (q),
17.7 (q), 16.6 (q) ppm. IR (neat): 2924, 1453, 1377, 1036, 832 cm-1. GC/MS (EI): m/z (%): 156 (8) [M+], 138 (5),
123 (12), 109 (5), 95 (37), 82 (100), 69 (71), 55 (25). HRMS (EI): m/z [M+], calcd for C10H20O: 156.1509; found:
156.1519. Odor description: fatty, citrus, green.
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2,6-dimethylnon-6-enal (15ck). Obtained from 10ck according to the procedure used for 15ba. Yield: 93%, b.p.
80°C/ 0.1mbar, colorless oil. 1H NMR (300 MHz, CDCl3): 9.58 (d, J = 1.8 Hz, 1H), 5.10 (t, J = 6.9 Hz, 1H), 2.41-
2.23 (m, 1H), 2.06-1.86 (m, 4H), 1.73-1.60 (m, 1H), 1.55 (s, 3H, Me), 1.50-1.24 (m, 3H), 1.06 (t, J = 7.0 Hz, 3H,
Me), 0.90 (t, J = 7.5 Hz, 3H, Me) ppm. 13C NMR (75 MHz, CDCl3): 205.2 (d), 133.7 (s), 126.9 (d), 46.2 (d), 39.4
(t), 30.0 (t), 25.1 (t), 21.1 (t), 15.6 (q), 14.3 (q), 13.3 (q) ppm. IR (neat): 2933, 1725, 1459, 1378, 1062, 928, 884
cm-1. GC/MS (EI): m/z (%): 168 (2) [M+], 150 (18), 135 (10), 126 (31), 110 (48), 95 (88), 81 (47), 69 (70), 55
(100). HRMS (EI): m/z [M+], calcd for C11H20O: 168.1509; found: 168.1513. Odor description: green, fatty,
cucumber, citrus, watery green, citronellal.
2,6-Dimethylnon-6-en-1-ol (16ck) Obtained from 15ck according to the procedure used for 16ba. Yield: 86%,
1
b.p. 130°C/0.1mbar, colorless oil. H NMR (300 MHz, CDCl3): 5.10 (t, J = 6.9 Hz, 1H), 3.55-3.33 (m, 2H), 2.07-
1.85 (m, 4H), 1.63-1.52 (m, 4H), 1.51-1.24 (m, 3H), 1.16-0.98 (m, 1H), 0.96-0.86 (m, 6H) ppm. 13C NMR (75 MHz,
CDCl3): Major (6E)-isomer: 134.4 (s), 126.4 (d), 68.3 (t), 39.8 (t), 35.7 (d), 32.7 (t), 25.3 (t), 21.1 (t), 16.6 (q), 15.7
(q), 14.4 (q) ppm. Minor (6Z)-isomer: 134.6 (s), 127.2 (d), 68.3 (t), 35.7 (d), 33.0 (t), 31.8 (t), 25.4 (d), 23.3 (q),
21.0 (t), 16.5 (q), 14.6 (q) ppm. IR (neat): 2930, 1460, 1378, 1030 cm-1. GC/MS (EI): m/z (%): 170 (19) [M+], 152
(3), 137 (7), 123 (18), 109 (48), 95 (52), 81 (100), 69 (68), 55 (97). HRMS (EI): m/z [M+], calcd for C11H22O,
170.1665; found: 170.1671. Odor description: floral, rose, fresh, fatty.
2,4,6-Trimethylhept-6-enal (15bd). Obtained from 10bd according to the procedure used for 15ba. Yield: 84%,
b.p. 110°C/10mbar, colorless oil. 1H NMR (300 MHz, CDCl3): 9.60/9.55 (2d, J = 1.7 Hz, 1H), 4.74 (s, 1H), 4.65 (s,
1H), 2.55-2.34 (m, 1H), 2.06-1.77 (m, 2H), 1.75-1.58 (m, 4H), 1.56-1.19 (m, 2H), 1.13-1.01 (m, 3H, Me), 0.89-
0.80 (m, 3H, Me) ppm. 13C NMR (75 MHz, CDCl3): 205.4/205.3 (2d), 144.1/144.0 (2s), 112.0 (t), 46.3/45.9 (2t),
44.2/44.1 (2d), 38.0/37.2 (2t), 28.3/28.0 (2d), 22.1 (q), 19.7/19.2 (2q), 14.3/13.2 (2q) ppm. IR (neat): 2965, 2919,
1726, 1649, 1457, 1377, 888 cm-1. GC/MS (EI): m/z (%): 154 (1) [M+], 139 (3), 121 (22), 107 (9), 96 (100), 83
(53), 69 (57), 55 (60). HRMS (EI): m/z [M+], calcd for C10H18O: 154.1352; found: 154.1356. Odor description:
green, agrestic.
2,4,6-Trimethylhept-6-en-1-ol (16bd). Obtained from 15bd according to the procedure used for 16ba. Yield:
75%, b.p. 108°C/0.2mbar, colorless oil. 1H NMR (300 MHz, CDCl3): 4.74 (s, 1H), 4.66 (s, 1H), 3.59-3.29 (m, 2H),
2.11-1.57 (m, 8H), 1.39-1.21 (m, 1H), 1.16-1.01 (m, 1H), 0.99-0.75 (m, 6H) ppm. 13C NMR (75 MHz, CDCl3):
144.7/144.6 (2s), 111.5/111.4(8) (2t), 69.0/68.2 (2t), 46.8/45.7 (2t), 40.9/40.2 (2t), 33.2/33.1 (2d), 28.0/27.6 (2t),
22.2/22.2 (2q), 20.2/19.2/17.4/16.1 (4q) ppm. IR (neat): 2955, 2916, 1456, 1376, 1037, 868 cm-1. GC/MS (EI):
m/z (%): 156 (1) [M+], 141 (1), 123 (13), 109 (5), 98 (25), 83 (100), 69 (56), 55 (98). HRMS (EI): m/z [M+], calcd
for C10H20O: 156.1509; found: 156.1515. Odor description: green, fatty, floral, rice bran, straw.
2,4,7-Trimethyl-6-methyleneoctanal (15bj). Obtained from 10bj according to the procedure used for 15ba.
Yield: 86%, b.p. 131°C/20mbar, colorless oil. 1H NMR (300 MHz, CDCl3): 9.57/9.53 (2d, J = 1.7 Hz, 1H), 4.77 (s,
1H), 4.63 (s, 1H), 2.54-2.32 (m, 1H), 2.23-1.98 (m, 1H), 1.94-1.57 (m, 3H), 1.54-1.20 (m, 2H), 1.12-0.94 (m, 9H),
0.90-0.78 (m, 3H) ppm. 13C NMR (75 MHz, CDCl3): 205.3/205.2 (2d), 153.9/153.8 (2s), 108.2 (t), 44.3/44.1 (2d),
43.3/42.9 (2t), 38.2/37.3 (2t), 33.0/32.9 (2d), 28.7/28.4 (2d), 21.9/21.8 (2q), 21.8/21.7 (2q), 19.8/19.3 (2q),
14.3/13.2 (2q) ppm. IR (neat): 2962, 1726, 1641, 1459, 1378, 891 cm-1. GC/MS (EI): m/z (%): 182 (1) [M+], 167
(4), 150 (5), 140 (12), 124 (54), 109 (48), 95 (18), 83 (30), 69 (100), 55 (49). HRMS (EI): m/z [M+], calcd for
C12H22O: 182.1665; found: 182.1670. Odor description: green, fatty, straw, citrus.
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