Avoiding olefin isomerization during decyanation of alkylcyano α,ω-dienes: A deuterium labeling and structural study of mechanism

Article abstract of DOI:10.1021/jo800640j

(Chemical Equation Presented) A two-step synthetic pathway involving decyanation chemistry for the synthesis of pure alkyl α,ω-dienes in quantitative yields is presented. Prior methodologies for the preparation of such compounds required 6-9 steps, sometimes leading to product mixtures resulting from olefin isomerization chemistry. This isomerization chemistry has been eliminated. Deuteration labeling and structural mechanistic investigations were completed to decipher this chemistry. Deuterium labeling experiments reveal the precise nature of this radical decyanation chemistry, where an alcohol plays the role of hydrogen donor. The correct molecular design to avoid competing intramolecular cyclization, and the necessary reaction conditions to avoid olefin isomerization during the decyanation process are reported herein.

Full text of DOI:10.1021/jo800640j

Avoiding Olefin Isomerization During Decyanation of Alkylcyano
r,ω-Dienes: A Deuterium Labeling and Structural Study of
Mechanism
Giovanni Rojas and Kenneth B. Wagener*
Center for Macromolecular Science and Engineering, George and Josephine Butler Polymer Research
Laboratory, Department of Chemistry, UniVersity of Florida, GainesVille, Florida 32611-7200
wagener@chem.ufl.edu
ReceiVed March 24, 2008
A two-step synthetic pathway involving decyanation chemistry for the synthesis of pure alkyl R,ω-
dienes in quantitative yields is presented. Prior methodologies for the preparation of such compounds
required 6-9 steps, sometimes leading to product mixtures resulting from olefin isomerization chemistry.
This isomerization chemistry has been eliminated. Deuteration labeling and structural mechanistic
investigations were completed to decipher this chemistry. Deuterium labeling experiments reveal the
precise nature of this radical decyanation chemistry, where an alcohol plays the role of hydrogen donor.
The correct molecular design to avoid competing intramolecular cyclization, and the necessary reaction
conditions to avoid olefin isomerization during the decyanation process are reported herein.
1. Introduction
cyanide moiety with concomitant formation of a radical.12 Even
so, reaction conditions can be harsh when other functionalities
not compatible with alkali metals or radical species are present.
For example, compounds containing olefin functionalities can
undergo structural isomerization via radical intermediates. This
is the case for R,ω-dienes, which can isomerize to internal
olefins. To circumvent this isomerization problem, we have
applied a previously reported method for the decyanation of
alkylcyano R,ω-dienes while completely avoiding isomeriza-
tion.13 This paper describes the necessary conditions to do so.
Olefin metathesis has proven to be an excellent synthetic tool
for carbon-carbon bond formation via a variety of methodolo-
gies, two of which require dienes. R,ω-Dienes are usually
employed in ring-closing metathesis (RCM) and acyclic diene
metathesis (ADMET) chemistry, where the preparation of pure
terminal olefins can be synthetically challenging.1 In many cases,
alkene isomerization occurs as a detrimental side reaction, not
only reducing yield but also generating a difficult-to-purify
mixture of products with internal olefins. Nitrile chemistry is
often employed because of the high alkylation yield and ease
of subsequent decyanation,2 where decyanation is usually carried
2. Results and Discussion
out by electron transfer chemistry initiated by alkali metals, such
2.1. Synthetic Approach to Alkyl r,ω-Dienes via
Decyanation Chemistry. Most methods for the preparation of
6–9
as Li,3–5 Na,
or K.10,11 The reaction proceeds in excellent
yield via a radical anion intermediate, which eliminates a
(7) Nemoto, H.; Hashimoto, M.; Kurobe, H.; Fukumoto, K.; Kametani, T.
J. Chem. Soc., Perkin Trans. 1 1985, 927–934.
(1) Baughman, T. W.; Sworen, J. C.; Wagener, K. B. Tetrahedron 2004, 60,
10943–10948.
(8) Nemoto, H.; Nagai, M.; Abe, Y.; Moizumi, M.; Fukumoto, K.; Kametani,
T. J. Chem. Soc., Perkin Trans. 1 1987, 1727–1733.
(2) Rojas, G.; Baughman, T. W.; Wagener, K. B. Synth. Commun. 2007, 37,
3923–3931.
(9) Walter, L. A.; McElvain, S. M. J. Am. Chem. Soc. 1934, 56, 1614–1616.
(10) Savoia, D.; Tagliavini, E.; Trombini, C.; Umani-Ronchi, A. J. Org.
Chem. 1980, 45, 3227–3229.
(3) Franck-Neumann, M.; Miesch, M.; Lacroix, E.; Metz, B.; Kern, J. M.
Tetrahedron 1992, 48, 1911–1926.
(4) Rychnovsky, S. D.; Griesgraber, G.; Kim, J. S. J. Am. Chem. Soc. 1994,
116, 2621–2622.
(11) Ra, C. S.; Kim, Y. S. Bull. Korean Chem. Soc. 1997, 18, 151–155.
(12) Mattalia, J. M.; Marchi-Delapierre, C.; Hazimeh, H.; Chanon, M. ArkiVoc
2006, 90, 118.
(5) Arapakos, P. G.; Scott, M. K.; Huber, F. E. J. Am. Chem. Soc. 1969, 91,
2059–2062.
(13) Cuvigny, T.; Larcheve, M.; Normant, H. C. R. Hebd. Seances Acad.
Sci., Ser. C 1972, 274, 797–799.
(6) Kraus, G. A.; Hon, Y. S. J. Org. Chem. 1985, 50, 4605–4608.
4962 J. Org. Chem. 2008, 73, 4962–4970
10.1021/jo800640j CCC: $40.75 2008 American Chemical Society
Published on Web 06/10/2008

Decyanation of Alkylcyano R,ω-Dienes
SCHEME 1. Synthesis of Alkyl r,ω-Dienes
TABLE 1. Different Decyanation Systems for the Reduction of 1d to 12-Butyltricosa-1,22-diene 2d
entry
1
system
K0, Al2O3
solvent
reaction time
yield (%)a
olefin isomerization (%)b
hexane
hexane
hexane/toluene (1:1)
toluene
hexane/ether (1:1)
ether
5 min
10 min
10 min
10 min
3 h
20
30
19
22
41
99
7
20
63
75
BD
BD
2
K0, Al2O3, toluene
3
4
K0, Ph3CH
K0, HMPA, t-BuOH
3 h
a Yield after purification by column chromatography, b Percentage of olefin isomerization detected by NMR and confirmed by GC. BD ) below 1H
and 13C NMR detection limit.
SCHEME 2. Synthesis of 12-Butyltricosa-1,22-diene 2d
Bierenbaum reported the decyanation of ꢀ,γ-unsaturated nitriles
using alkali metals in liquid ammonia with yields greater than
90%, yet they obtained a mixture of products due to olefin
isomerization.27 Cuvigny reported the use of alkali metals in
HMPA and ether in the presence of various alcohols with yields
13
from 16% to 89%. Other groups have modified Cuvigny’s
methodology for the synthesis of vitamin D derivatives with
yields from 70% to 90%.22–24 While this methodology has
proven to be useful with various substrates, studies containing
alkene molecules susceptible to promote olefin isomerization
as described here have not been reported.
Our investigation began by exploring several methods for the
reductive elimination of the nitrile functional group from model
compound 1d. The different reaction conditions and observed
results are shown in Scheme 2 and Table 1.
alkyl R,ω-dienes require as many as 9 synthetic steps resulting
in low yields.14–16 We have reduced the number of steps to 2,
previously reported alkylation2 followed by decyanation, while
producing analytically pure dienes. Further yet, a variety of
synthetic routes can be required just for the preparation R,ω-
dienes simply possessing different alkyl substituents. For
example, three independent methodologies have been used for
synthesizing R,ω-dienes possessing methyl,17–19 ethyl,16,20 and
hexyl21 substituents.
The first experiment (entry 1) involved the use of potassium
metal on alumina in dry hexane, yielding 20% decyanation and
giving 7% olefin isomerization after 5 min of reaction. After
10 min, the same reaction conditions produced 30% decyanation
with 20% olefin isomerization, where the extent of isomerization
The need for a high yield, universal synthesis having fewer
steps motivated us to explore more sophisticated nitrile chem-
istry, since primary nitriles 19 have been dialkenylated using
lithium diisopropylamide (LDA) in quantitative yields.2 Sub-
sequent decyanation of the resulting alkylcyano R,ω-dienes 1
produces alkyl R,ω-dienes 2, as shown in Scheme 1. This paper
focuses on alkyl R,ω-dienes with 9 methylene spacers between
the double bond and the tertiary carbon. Syntheses of analogous
compounds with various spacer lengths can also be achieved.
Previous work has shown that reductive elimination of nitriles
by electron transfer works for primary, secondary, and tertiary
nitriles using various alkali metals in ammonia,3–8 potassium
in hexamethylphosphoramide (HMPA),22–25 or potassium with
dicyclohexyl-18-C-6 in toluene.26 Although decyanation of
alkylnitriles by alkali metals in liquid ammonia is quite versatile,
it does not offer utility when other functionalities are present
in the molecule, such as olefins. For example, Marshall and
1
was calculated from H NMR spectra by comparison of the
relative areas of the terminal and internal olefin signals (see
Figure 1). The observed results suggested that a tertiary radical
is formed after the reductive elimination of nitrile, where the
translocation of this radical to a more stable allyl radical leads
to the olefin isomerization product (Scheme 3).
Different systems involving a radical trap were developed in
order to prove the concept of radical translocation. Formation
of a more stable species must occur to avoid translocation of
the tertiary radical to an allylic radical. Furthermore, the stable
species must be produced at a higher rate than the allylic radical
formation in order to tune the reaction toward decyanation
without olefin isomerization. Toluene was added to the reaction
mixture with the intent of forming a stable benzyl radical, as
indicated in Table 1, entry 2. Decyanation occurred in 19-22%
42.(14) Baughman, T. W.; Wagener, K. B. Metathesis Polym. 2005, 176, 1–
(15) Berda, E. B.; Baughman, T. W.; Wagener, K. B. J. Polym. Sci. Part A:
Polym. Chem. 2006, 44, 4981–4989.
(16) Rojas, G.; Wagener, K. In Metathesis Chemistry; Springer: New York,
2007; pp 305-324.
(22) Sicinski, R. R.; Perlman, K. L.; Prahl, J.; Smith, C.; DeLuca, H. F.
J. Med. Chem. 1996, 39, 4497–4506.
(17) Smith, J. A.; Brzezinska, K. R.; Valenti, D. J.; Wagener, K. B.
Macromolecules 2000, 33, 3781–3794.
(23) Fall, Y.; Torneiro, M.; Castedo, L.; Mourino, A. Tetrahedron Lett. 1992,
33, 6683–6686.
(18) Wagener, K. B.; Valenti, D.; Hahn, S. F. Macromolecules 1997, 30,
6688–6690.
(24) Torneiro, M.; Fall, Y.; Castedo, L.; Mourino, A. Tetrahedron Lett. 1992,
33, 105–108.
(19) Sworen, J. C.; Smith, J. A.; Wagener, K. B.; Baugh, L. S.; Rucker,
S. P. J. Am. Chem. Soc. 2003, 125, 2228–2240.
(25) Debal, A.; Cuvigny, T.; Larcheveque, M. Synthesis (Stuttgart) 1976,
391–393.
(20) Sworen, J. C.; Smith, J. A.; Berg, J. M.; Wagener, K. B. J. Am. Chem.
Soc. 2004, 126, 11238–11246.
(26) Ohsawa, T.; Kobayashi, T.; Mizuguchi, Y.; Saitoh, T.; Oishi, T.
Tetrahedron Lett. 1985, 26, 6103–6106.
(21) Sworen, J. C. Ph.D. Dissertation, University of Florida, 2004.
(27) Marshall, J. A.; Bierenbaum, R. J. Org. Chem. 1977, 42, 3309–3311.
J. Org. Chem. Vol. 73, No. 13, 2008 4963

Rojas and Wagener
1
FIGURE 1. Expanded H NMR spectrum of 12-butyltricosa-1,22-diene 2d at three different degreees of olefin isomerization.
TABLE 2. Decyanation of Alkylcyano r,ω-Dienes Using
Potassium Metal, HMPA, and t-BuOH in Ether
SCHEME 3. Proposed Mechanism for Olefin Isomerization
via Formation of an Allylic Radical
yield with 63-75% olefin isomerization. Although formation
of benzyl radical cannot be ruled out, formation of the allylic
radical seems to occur at a faster rate, thus promoting olefin
isomerization.
The third entry in Table 1 shows the result of incorporation
of triphenylmethane as a radical trap. The reductive elimination
of the nitrile functional group in the presence of Ph3CH in
hexane/ether (1:1) produced the desired decyanation product
in 41% yield; hydrogen radical transfer from the triphenyl-
methane molecule to the tertiary radical formed by decyanation
occurs to produce the desired product without structural olefin
isomerization. The absence of isomerized internal double bonds
suggests that the more stable triphenylmethyl radical forms more
quickly than does the allylic radical, which would lead to olefin
isomerization. Although the triphenylmethyl radical was ob-
served during the reaction by the appearance of a yellowish
solution, competition between the radical trapping process and
deprotonation of Ph3CH initiated by potassium metal is also
plausible.28–32 The initial yellow solution gradually converted
to an intense red color due to formation of the triphenylmethyl
anion, which deactivates the decyanation process and decreases
the reaction yield.
a Yield after purification by column chromatography. b Percentage of
olefin isomerization detected by NMR and confirmed by GC. B.D )
1
below H and 13C NMR detection limit.
without apparent olefin isomerization. The absence of isomerized
product suggests that the tertiary radical formed after the
reductive elimination of nitrile, before producing an allylic
Entry 4 in Table 1 shows the decyanation of 1d using
potassium metal, HMPA, and t-BuOH with quantative yields
4964 J. Org. Chem. Vol. 73, No. 13, 2008

Decyanation of Alkylcyano R,ω-Dienes
FIGURE 2. Deuterium-NMR of 12-d-12-methyl-tricosa-1,22-diene.
TABLE 3. Decyanation of 1a in the Presence of Deuterated
Compounds
radical, quickly abstracts hydrogen from the alcohol or it is
reduced yielding a carbanion, which inactivates the tertiary
radical and consequently its structural isomerization. Although
formation of tert-butoxyl radicals from tert-butanol is not
common,33–35 alkoxyl radicals rapidly abstract hydrogen from
the R-carbon in the alcohol or solvent or disproportionate
yielding a tert-butoxide anion.36–39
yield
extent of
olefin
entry decyanation system (%)a deuteration (%)b isomerization (%)c
1
2
3
4
K0, HMPA, t-BuOD
99
92
not detected
91
BD
BD
BD
K0, HMPA-d18, t-BuOH 99
K0, t-BuOD
t-BuO-K+
12
0
To further expand the scope of this method, a series of
alkylcyano R,ω-dienes was decyanated resulting in quantitative
yields with no apparent olefin isomerization, as shown in Table
2. Obviously the method has broad utility. Prior methodologies
for the preparation of alkyl R,ω-dienes require 6-9 synthetic
steps; this approach requires 2 steps, alkylation2 and decyana-
tion, and circumvents side reactions, providing a universal, high
yielding route to pure alkyl R,ω-dienes.
a Yield after purification by column chromatography. b Extend of
deuteration detected by 1H NMR and deuterium-NMR. c Percentage of
isomerized product detected by 1H NMR and confirmed by GC. BD )
1
below H and 13C NMR detection limit.
SCHEME 4. Decyanation of 1a in the Presence of
Deuterated tert-Butanol
2.2. Deuterium Labeling and Mechanistic Considerations.
Cuvigny speculated that HMPA is the hydrogen donor in the
reductive elimination of nitriles, but no chemical or spectro-
scopic proof has been reported to date.13 Two possible sources
of hydrogen radicals are present in the reactions we describe,
HMPA and t-BuOH.40 The reaction is carried out as a mixture
of potassium metal and HMPA in ether, followed by dropwise
addition of the nitrile dissolved in t-BuOH and ether. Experi-
ments in deuterated alcohol were performed to determine the
origin of the hydrogen captured after the reductive elimination
of nitrile (Table 3). The first test involved the dropwise addition
of a mixture of 1a and t-BuOD in ether to a solution of
potassium metal and HMPA in ether, yielding the decyanation
product 3 (Scheme 4) in quantitative yield without apparent
olefin isomerization. Figure 2 shows the deuterium-NMR
spectrum of 3, where one singlet at δ1.38, corresponding to
the monodeuteration of the tertiary carbon, is observed. Figure
3 shows the 13C NMR spectra of the products formed in the
presence t-BuOH (Figure 3a) and t-BuOD (Figure 3b). The
intensity of the tertiary carbon signal at 33.02 ppm is much
smaller in the monodeuterated product 3 due to the larger 13C
relaxation time in the absence of directly bonded protons. The
extent of deuteration of the final product was calculated by
integration of the 1H NMR signals from the methyl at the branch
point, singlet in the deuterated product versus doublet in the
(28) Arapakos, P. G.; Scott, M. K.; Huber, F. E. J. Am. Chem. Soc. 1969,
91, 2059–2062.
(29) Gomberg, M. J. Am. Chem. Soc. 1900, 22, 757–771.
(30) Gomberg, M. J. Am. Chem. Soc. 1901, 23, 496–502.
(31) Lankamp, H.; Nauta, W. T.; MacLean, C. Tetrahedron Lett. 1968, 9,
249–254.
1
product with H on the tertiary carbon, as shown in Figure 4.
(32) McBride, J. M. Tetrahedron 1974, 30, 2009–2022.
(33) Yan, X. M.; Robbins, M. D.; White, J. M. J. Phys. Chem. B 2004, 108,
18925–18931.
The results indicated that 3 was 92% deuterated. The high extent
of deuteration confirms that the hydrogen from the alcohol is
captured by the tertiary radical from the reductive elimination
of nitrile.
The second entry in Table 3 describes the decyanation
experiment using HMPA with all methyl groups isotopically
labeled with deuterium. As with the previous experiments, the
reaction produced decyanation in quantitative yield without
apparent olefin isomerization. Deuterium NMR experiments
(34) Ashworth, B.; Gilbert, B. C.; Norman, R. O. C. J. Chem. Res., Synop.
1977, 94–95.
(35) Brainard, R. L.; Madix, R. J. J. Am. Chem. Soc. 1987, 109, 8082–8083.
(36) Mortensen, A.; Skibsted, L. H. FEBS Lett. 1998, 426, 392–396.
(37) Moger, C.; Gyor, M. Tetrahedron Lett. 1989, 30, 7467–7468.
(38) Stolze, K.; Udilova, N.; Nohl, H. Free Radical Biol. Med. 2000, 29,
1005–1014.
(39) Verdin, D. Int. J. Radiat. Phys. Chem. 1970, 2, 201–208.
(40) Cuvigny, T.; Larcheveque, M.; Normant, H. Bull. Soc. Chim. Fr. 1973,
3, 1174–1178.
J. Org. Chem. Vol. 73, No. 13, 2008 4965

Rojas and Wagener
FIGURE 3. 13C NMR comparison of (a) 12-methyltricosa-1,22-diene and (b) 12-d-12-methyl-tricosa-1,22-diene.
FIGURE 4. 1H NMR methyl resonances of (a) 12-d-12-methyl-tricosa-1,22-diene (singlet with a small contribution of residual doublet) and (b)
12-methyltricosa-1,22-diene (doublet).
showed no apparent deuteration in the final product when the
isotopic label is carried by the HMPA, clearly showing that the
hydrogen from the alcohol, and not from HMPA, is captured
by the tertiary radical during the reductive elimination of nitrile.
The third entry in Table 3 shows the reaction conditions when
decyanation occurs in the absence of HMPA, resulting in 12%
decyanation with no apparent olefin isomerization. Deuterium-
NMR showed a singlet at δ1.38, which corresponds to the
4966 J. Org. Chem. Vol. 73, No. 13, 2008

Decyanation of Alkylcyano R,ω-Dienes
SCHEME 5. Decyanation of
2-Alkyl-2-pent-4-enyl-hept-6-enenitrile
formation of 3. The low yield in this reaction is explained by
the absence of HMPA, which apparently stabilizes the formation
of the intermediate species.
The fourth experiment in Table 3 was designed to determine
if reductive elimination is carried out by potassium metal or by
the potassium tert-butoxide possibly formed in situ. The reaction
was performed via dropwise addition of 1a in ether to a solution
of potassium metal and t-BuOD in ether. The starting material
1a was recovered and no decyanation product 3 was detected.
These results demonstrate that reductive elimination of nitrile
occurs by electron transfer from potassium metal and not via
t-BuOK formed in situ.
Although decyanation methodology using potassium metal
and HMPA appears to occur through a radical-intermediate
mechanism, no definitive proof of this has been clearly presented
to date.41 Formation of a carbanion via reduction of the radical-
intermediate species cannot be ruled out.40 One way to provide
evidence for a free radical-intermediate would be to capture it
via intramolecular cyclization before reduction to the carbanion
occurs. Alkenes capture radical moieties which can subsequently
undergo rapid intraradical cyclization to form cyclic radicals.42–45
To prove the point, decyanation was performed using
alkylcyano R,ω-dienes 4a and 4b possessing only three meth-
ylene units between the terminal double bonds and the nitrile,
in order to enhance the likelihood for cyclization to occur
(Scheme 5).46–48 In fact, bicyclic products 10 and 11 form as a
result of intramolecular radical capture. Decyanation of 4
produces a tertiary radical 5, which undergoes 5-exo and 6-endo
ring closures 6 and 7, leading to the bicyclic structures 10 and
11.
To further determine the influence of spacer length on the
cyclization pathway, a series of experiments were performed
using alkylcyano ω-alkenes 13 possessing spacers of 3, 4, 5,
and 6 methylene groups (Scheme 6). Compounds with three
and four methylene units between the terminal double bond and
the nitrile formed cyclic products 15 and 16. Structures with
five and six methylene spacers yielded only linear structures.
These results verified that at least five CH2 spacers are needed
between the double bond and the carbon bearing the nitrile group
to prevent radical-induced cyclization.49–51
SCHEME 6. Decyanation of Alkenylnitriles
All of these results suggest a plausible mechanism involving
a radical-intermediate for the reductive elimination of CN in
the presence of potassium, HMPA and t-BuOH (Scheme 7).
Transfer of one electron from potassium metal to the nitrile
group results in formation of a radical anion. Subsequent
elimination of cyanide yields a tertiary radical that is rearranged
to form cyclic molecules 10, 11, 15, and 16, quenched by
abstraction of hydrogen from t-BuOH to yield 2a-f, or reduced
to a carbanion followed by protonation from t-BuOH to yield
(41) Fleming, F. F.; Zhang, Z. Y. Tetrahedron 2005, 61, 747–789.
(42) Denisova, T. G.; Denisov, E. T. Russ. Chem. Bull. 2002, 51, 949–960.
(43) Ha, C.; Horner, J. H.; Newcomb, M.; Varick, T. R.; Arnold, B. R.;
Lusztyk, J. J. Org. Chem. 1993, 58, 1194–1198.
(44) Sturino, C. F.; Fallis, A. G. J. Org. Chem. 1994, 59, 6514–6516.
(45) Beckwith, A. L. J.; Bowry, V. W.; Schiesser, C. H. Tetrahedron 1991,
47, 121–130.
(46) Beckwith, A. L. J. Tetrahedron 1981, 37, 3073–3100.
(47) Stork, G.; Baine, N. H. J. Am. Chem. Soc. 1982, 104, 2321–2323.
(48) Beckwith, A. L. J.; Phillipou, G.; Serelis, A. K. Tetrahedron Lett. 1981,
22, 2811–2814.
(49) Gomez, A. M.; Company, M. D.; Uriel, C.; Valverde, S.; Lopez, J. C.
Tetrahedron Lett. 2002, 43, 4997–5000.
(50) Julia, M. Acc. Chem. Res. 1971, 4, 386–392.
2a-f. Abstraction of hydrogen from t-BuOH avoids formation
of allylic radicals and consequent olefin isomerization.
(51) Beckwith, A. L.; Moad, G. J. Chem. Soc., Chem. Commun. 1974, 472–
473.
J. Org. Chem. Vol. 73, No. 13, 2008 4967

Rojas and Wagener
SCHEME 7. Proposed Mechanism for the Reductive Elimination of Nitrile
13C NMR (CDCl3) δ (ppm) 14.4, 23.4, 24.5, 26.9, 29.2, 29.4, 29.8,
29.9, 29.9, 30.4, 33.6, 33.9, 34.1, 37.6, 114.3, 139.5; EI/HRMS
[M]+ calcd for C27H52: 376.4069; found 376.4035. Anal. Calcd for
C27H52: 86.09 C, 13.91 H; found 86.09 C, 13.90 H.
Decyanation of 2-Butyl-2-(undec-10-enyl)tridec-12-enenitrile
(1d) in Toluene. Synthesis of 12-Butyltricosa-1,22-diene (2d).
After purification, 21 mg (22% yield) of a colorless liquid was
collected. The following spectral properties were observed: 1H NMR
(CDCl3) δ (ppm) 0.90 (t, 3H), 1.23-1.41 (m, 39H), 2.04 (q, 4H),
4.97 (m, 4H), 5.42 (m, 6H), 5.82 (m, 2H); 13C NMR (CDCl3) δ
(ppm) 14.4, 23.4, 24.5, 26.9, 29.2, 29.4, 29.8, 29.9, 29.9, 30.4, 33.6,
33.9, 34.1, 37.6, 114.3, 139.5; EI/HRMS [M]+ calcd for C27H52:
376.4069; found 376.4074. Anal. Calcd for C27H52: 86.09 C, 13.91
H; found 86.11 C, 13.91 H.
3. Conclusions
The understanding of the mechanism for reductive elimination
of nitriles opens the possibility for the synthesis of alkyl R,ω-
dienes. Previously reported methodologies for the preparation
of 2a, 2b, and 2f require 6-9 synthetic steps. This new
methodology allows quantitative synthesis of such dienes in 2
steps and circumvents side reactions such as structural olefin
isomerization and intramolecular cyclization. We believe this
to be a universal synthesis route for the preparation of alkyl
R,ω-dienes.
4. Experimental Section
4.2. Decyanation of 2-Butyl-2-(undec-10-enyl)tridec-12-eneni-
trile (1d) with Potassium Metal and Triphenylmethane. Syn-
thesis of 12-Butyltricosa-1,22-diene (2d). Potassium metal (49 mg,
1.25 mmol) and hexane (10 mL) were transferred to a three-neck
round-bottom flask equipped with a stir bar, addition funnel, and
argon inlet adaptor. A solution of 1d (0.10 g, 0.3 mmol) and
triphenylmethane (183 mg, 0.75 mmol) in hexane (10 mL) and ether
(1.5 mL) was added dropwise to the reactor and stirred for 3 h.
The reaction was quenched with water (5 mL), extracted three times
with ether (300 mL), and washed with brine (100 mL). After drying
over MgSO4, the solution was filtered, concentrated by rotary
evaporation, and purified by flash column chromatography (hexane).
After purification, 38 mg (41% yield) of a colorless liquid was
collected. The following spectral properties were observed: 1H NMR
(CDCl3) δ (ppm) 0.90 (t, 3H), 1.23-1.41 (m, 39H), 2.04 (q, 4H),
4.97 (m, 4H), 5.82 (m, 2H); 13C NMR (CDCl3) δ (ppm) 14.4, 23.4,
24.5, 26.9, 29.2, 29.4, 29.8, 29.9, 30.4, 33.6, 33.9, 34.1, 37.6, 114.3,
139.5; EI/HRMS [M]+ calcd for C27H52: 376.4069; found 376.4061.
Anal. Calcd for C27H52: 86.09 C, 13.91 H; found 86.10 C, 13.90
H.
4.3. General Methodology of Decyanation Using Potassium
Metal and Hexamethylphosphoramide. Potassium metal (8.285
g, 212 mmol), HMPA (27.238 g, 152 mmol), and ether (185 mL)
were transferred to a three-neck round-bottom flask equipped with
a stir bar, addition funnel, and argon inlet adaptor. A solution of
the alkylcyano R,ω-diolefin (30 mmol) and t-BuOH (5.841 g, 79
mmol) in ether (130 mL) was added dropwise to the reactor and
stirred for 3 h at 0 °C. The reaction was monitored by TLC plate
using 5% ethyl acetate in hexane. When no trace of starting material
was observed by TLC, the remaining excess of unreacted potassium
was removed from the reaction flask. The reaction was quenched
with water (20 mL), extracted three times with ether (600 mL),
and washed with brine (150 mL). After drying over MgSO4, the
solution was filtered, concentrated by rotary evaporation, and
purified by flash column chromatography (hexane).
Materials. All starting materials were used as received, except
for 11-bromoundec-1-ene and the alkylcyano R,ω-dienes, which
were synthesized according to the literature procedures.1,2 Tetrahy-
drofuran, toluene, and ether were freshly distilled from Na/K alloy
using benzophenone as an indicator. The 11-bromoundec-1-ene,
hexamethylphosphoramide, diisopropylamine, propiononitrile, bu-
tyronitrile, pentanenitrile, hexanenitrile, heptanenitrile, and oc-
tanenitrile were freshly distilled from CaH2 prior to use. The tert-
butanol was dried over calcium oxide and freshly distilled before
use.
4.1. Decyanation of 2-Butyl-2-(undec-10-enyl)tridec-12-eneni-
trile (1d) with Potassium Metal and Neutral Alumina. The
decyanation of 1d (0.10 g, 0.3 mmol) was carried out in slurry of
potassium and neutral alumina as reported by Umani-Ronchi.10 The
reaction was monitored by TLC plate using 5% ethyl acetate in
hexane. When no trace of starting material was observed by TLC,
the remaining excess of unreacted potassium was removed from
the reaction flask. The reaction was quenched with water (20 mL),
extracted three times with ether (600 mL), and washed with brine
(150 mL). After drying over MgSO4, the solution was filtered,
concentrated by rotary evaporation, and purified by flash column
chromatography (hexane). Decyanation was carried out in hexane,
hexane/toluene (1:1), and toluene as described below.
Decyanation of 2-Butyl-2-(undec-10-enyl)tridec-12-enenitrile
(1d) in Hexane. Synthesis of 12-Butyltricosa-1,22-diene (2d).
After purification, 19 mg (20% yield) of a colorless liquid was
collected. The following spectral properties were observed: 1H NMR
(CDCl3) δ (ppm) 0.90 (t, 3H), 1.23-1.41 (m, 39H), 2.04 (q, 4H),
4.97 (m, 4H), 5.42 (m, 0.15H), 5.82 (m, 2H); 13C NMR (CDCl3) δ
(ppm) 14.4, 23.4, 24.5, 26.9, 29.2, 29.4, 29.8, 29.9, 29.9, 30.4, 33.6,
33.9, 34.1, 37.6, 114.3, 139.5; EI/HRMS [M]+ calcd for C27H52
376.4069, found 376.4050. Anal. Calcd for C27H52: 86.09 C, 13.91
H; found 86.02 C, 13.98 H.
Decyanation of 2-Butyl-2-(undec-10-enyl)tridec-12-enenitrile
(1d) in Hexane/Toluene 1:1. Synthesis of 12-Butyltricosa-1,22-
diene (2d). After purification, 18 mg (19% yield) of a colorless
liquid was collected. The following spectral properties were
12-Methyltricosa-1,22-diene (2a). After purification, 9.93 g
(99% yield) of a colorless liquid was collected. The following
spectral properties were observed: 1H NMR (CDCl3) δ (ppm) 0.84
(d, 3H), 1.23-1.39 (m, 33H), 2.04 (q, 4H), 4.97 (m, 4H), 5.82 (m,
1
observed: H NMR (CDCl3) δ (ppm) 0.90 (t, 3H), 1.23-1.41 (m,
39H), 2.04 (q, 4H), 4.97 (m, 4H), 5.42 (m, 3.4H), 5.82 (m, 2H);
4968 J. Org. Chem. Vol. 73, No. 13, 2008

Decyanation of Alkylcyano R,ω-Dienes
2H); 13C NMR (CDCl3) δ (ppm) 20.0, 27.4, 29.2, 29.4, 29.8, 29.9,
30.0, 30.3, 33.0, 34.1, 37.4, 114.3, 139.4; EI/HRMS [M]+ calcd
for C24H46: 334.3600; found 334.3607. Anal. Calcd for C24H46:
86.14 C, 13.86 H; found 86.15 C, 13.79 H.
12-Ethyltricosa-1,22-diene (2b). After purification, 10.24 g
(98% yield) of a colorless liquid was collected. The following
spectral properties were observed: 1H NMR (CDCl3) δ (ppm) 0.84
(t, 3H), 1.28-1.37 (m, 35H), 2.04 (q, 4H), 4.96 (m, 4H), 5.82 (m,
2H); 13C NMR (CDCl3) δ (ppm) 11.1, 26.1, 27.0, 29.2, 29.4, 29.8,
29.9, 30.0, 30.4, 33.4, 34.1, 39.1, 114.3, 139.5; EI/HRMS [M]+
calcd for C25H48: 348.3756; found 348.3758. Anal. Calcd for C25H48:
86.12 C, 13.88 H; found: 86.25 C, 13.97 H.
found 334.3605. Anal. Calcd for C24H46: 86.14 C, 13.86 H; found
86.12 C, 13.88 H.
4.5. Decyanation of Alkylcyano-1,10-undecadienes and Alk-
enenitriles. The decyanation of 4and 13 was carried out as described
in section 4.3. Characterization and purification of the respective
products was carried out by NMR and HPLC/MS. Two columns
were utilized: (1) analytical or scout scale column with dimensions
of 10.0 mm (inner diameter) by 250.0 mm; (2) preparative scale
with dimensions of 41.4 mm (inner diameter) by 250.0 mm. Both
columns were silica packed with a particle size of 8 µm and a pore
size of 60 Å. Crude samples were diluted in a 25% solution (w/v)
of HPLC grade hexanes and filtered prior to injection.
2-Propyltricosa-1,22-diene (2c). After purification, 10.76 g (99%
yield) of a colorless liquid was collected. The following spectral
properties were observed: 1H NMR (CDCl3) δ (ppm) 0.90 (t, 3H),
1.23-1.41 (m, 37H), 2.04 (q, 4H), 4.97 (m, 4H), 5.82 (m, 2H);
13C NMR (CDCl3) δ (ppm) 14.8, 20.1, 27.0, 29.2, 29.4, 29.8, 29.9,
30.0, 30.4, 34.0, 34.1, 36.4, 37.5, 114.3, 139.4; EI/HRMS [M]+
calcd for C26H50: 362.3913; found 362.3918. Anal. Calcd for C26H50:
86.10 C, 13.90 H; found 86.09 C, 13.91 H.
3a,7-Dimethyl-decahydroazulene (10a). After purification,
0.84 g (85% yield) of a colorless liquid was collected. The following
spectral properties were observed: 1H NMR (CDCl3) δ (ppm) 1.06
(d, 3H), 1.16 (s, 3H), 1.25-1.45 (m, 10H), 1.61-1.75 (m, 6H);
13C NMR (CDCl3) δ (ppm) 21.3, 22.6, 22.1, 23.5, 32.0, 33.3, 38.2,
39.0, 39.9, 41.4, 47.0, 48.0; EI/HRMS [M]+ calcd for C12H22:
166.1722; found 166.1725. Anal. Calcd for C12H22: 86.67 C, 13.33
H; found 86.63 C, 13.36 H.
12-Butyltricosa-1,22-diene (2d). After purification, 11.18 g
(99% yield) of a colorless liquid was collected. The following
spectral properties were observed: 1H NMR (CDCl3) δ (ppm) 0.90
(t, 3H,), 1.23-1.41 (m, 39H), 2.04 (q, 4H), 4.97 (m, 4H), 5.82 (m,
2H); 13C NMR (CDCl3) δ (ppm) 14.4, 23.4, 27.0, 29.2, 29.4, 29.8,
29.9, 30.0, 30.4, 33.7, 34.0, 34.1, 37.6, 114.3, 139.4; EI/HRMS
[M]+ calcd for C27H52: 376.4069; found 376.4061. Anal. Calcd for
C27H52: 86.09 C, 13.91 H; found 86.10 C, 13.90 H.
12-Pentyltricosa-1,22-diene (2e). After purification, 11.48 g
(98% yield) of a colorless liquid was collected. The following
spectral properties were observed: 1H NMR (CDCl3) δ (ppm) 0.90
(t, 3H), 1.23-1.41 (m, 41H), 2.04 (q, 4H), 4.97 (m, 4H), 5.82 (m,
2H); 13C NMR (CDCl3) δ (ppm) 14.4, 23.0, 26.7, 27.0, 29.2, 29.4,
29.7, 29.8, 29.9, 30.0, 30.4, 32.7, 33.9, 34.0, 34.1, 37.7, 114.3,
139.4; EI/HRMS [M]+ calcd for C28H54: 390.4226; found 390.4228.
Anal. Calcd for C28H54: 86.07 C, 13.93 H; found 86.05 C, 13.96
H.
3a-Butyl-7-methyl-decahydroazulene (10b). After purification,
0.82 g (83% yield) of a colorless liquid was collected. The following
spectral properties were observed: 1H NMR (CDCl3) δ (ppm) 0.96
(t, 3H), 1.06 (d, 3H), 1.16-1.48 (m, 14H), 1.60-1.75 (m, 8H);
13C NMR (CDCl3): δ(ppm): 14.1, 21.3, 22.4, 23.4, 23.8, 27.8, 32.3,
33.3, 36.4, 37.7, 38.2, 39.2, 39.3, 44.8, 54.7; EI/HRMS [M]+ calcd
for C15H28: 208.2191; found 208.2193. Anal. Calcd for C15H28:
86.46 C, 13.54 H; found 86.48 C, 13.52 H.
1,5-Dimethylbicyclo[4.3.1]decane (11a). After purification, 27
mg (3% yield) of a colorless liquid was collected. The following
spectral properties were observed: 1H NMR (CDCl3) δ (ppm) 1.06
(d, 3H), 1.16 (s, 3H), 1.10-1.26 (m, 9H), 1.31-1.51 (m, 6H),
1.61-1.70 (m, 1H); 13C NMR (CDCl3) δ (ppm) 18.8, 21.4, 22.1,
25.4, 31.7, 35.7, 37.2, 40.1, 40.9, 41.6, 42.7, 43.4; EI/HRMS [M]+
calcd for C12H22: 166.1722; found 166.1720. Anal. Calcd for C12H22:
86.67 C, 13.33 H; found 86.61 C, 13.39 H.
1-Butyl-5-methylbicyclo[4.3.1]decane (11b). After purification,
18 mg (2% yield) of a colorless liquid was collected. The following
spectral properties were observed: 1H NMR (CDCl3) δ (ppm) 0.96
(t, 3H), 1.06 (d, 3H), 1.10-1.51 (m, 21H), 1.61-1.70 (m, 1H);
13C NMR (CDCl3) δ (ppm) 14.1, 18.8, 21.7, 22.4, 23.4, 27.5, 31.7,
35.7, 37.5, 39.2, 39.4, 40.1, 40.5, 41.2; EI/HRMS [M]+ calcd for
C15H28: 208.2191; found 208.2188. Anal. Calcd for C15H28: 86.46
C, 13.54 H; found 86.43 C, 13.56 H.
12-Hexyltricosa-1,22-diene (2f). After purification, 12.01 g (99%
yield) of a colorless liquid was collected. The following spectral
properties were observed: 1H NMR (CDCl3) δ (ppm) 0.89 (t, 3H),
1.15-1.48 (m, 43H), 2.04 (q, 4H), 4.97 (m, 4H), 5.82 (m, 2H);
13C NMR (CDCl3) δ (ppm) 14.4, 23.0, 26.9, 29.2, 29.4, 29.8, 29.9,
29.9, 30.1, 30.4, 32.2, 33.9, 34.1, 37.6, 114.3, 139.5; EI/HRMS
[M]+ calcd for C29H56: 404.4382; found 404.4386. Anal. Calcd for
C29H56: 86.05 C, 13.95 H; found 86.38 C, 13.97 H.
1,2-Dimethylcyclopentane (15a). After purification, 0.94 g (95%
yield) of a colorless liquid was collected. The following spectral
properties were observed: 1H NMR (CDCl3) δ (ppm) 1.06 (d, 6H),
1.25-1.75 (m, 8H); 13C NMR (CDCl3): δ(ppm): 17.9, 25.4, 36.1,
45.3; EI/HRMS [M]+ calcd for C7H14: 98.1096; found 98.1094.
Anal. Calcd for C7H14: 85.63 C, 14.37 H; found 85.61 C, 14.39 H.
1-Butyl-2-methylcyclopentane (15b). After purification, 0.89 g
(90% yield) of a colorless liquid was collected. The following
spectral properties were observed: 1H NMR (CDCl3) δ (ppm) 0.96
(t, 3H), 1.06 (d, 3H), 1.29-1.60 (m, 14H); 13C NMR (CDCl3) δ
(ppm) 14.1, 18.2, 23.1, 25.7, 30.0, 31.8, 33.9, 36.4, 43.1, 46.4; EI/
HRMS [M]+ calcd for C10H20: 140.1565; found 140.1568. Anal.
Calcd for C10H20: 85.63 C, 14.37 H; found 85.61 C, 14.40 H.
1,2-Dimethylcyclohexane (15c). After purification, 0.71 g (71%
yield) of a colorless liquid was collected. The following spectral
properties were observed: 1H NMR (CDCl3) δ (ppm) 1.06 (m, 6H),
1.20-1.65 (m, 10H); 13C NMR (CDCl3) δ (ppm) 18.2, 25.8, 33.3,
40.3; EI/HRMS [M]+ calcd for C8H16: 112.1252; found 112.1250.
Anal. Calcd for C8H16: 85.63 C, 14.37 H; found 85.67 C, 14.31 H.
1-Butyl-2-methylcyclohexane (15d). After purification, 0.68 g
(68% yield) of a colorless liquid was collected. The following
spectral properties were observed: 1H NMR (CDCl3) δ (ppm) 0.96
(t, 3H), 1.06 (d, 3H), 1.20-1.50 (m, 16H); 13C NMR (CDCl3) δ
(ppm) 14.1, 18.5, 23.1, 25.8, 26.1, 30.0, 31.1, 32.1, 33.6, 38.1, 42.5;
4.4. Decyanation Using Isotopic Labeling with Deuterium.
The decyanation of 1a was carried out in presence of deuterated
t-butanol or HMPA-d18 using the general decyanation procedure
described in section 4.3.
Decyanation using Potassium Metal, Hexamethylphosphora-
mide, and 2-Methyl-2-propan-[2H]-ol. Synthesis of [12-2H]-12-
Methyltricosa-1,22-diene (3). After purification, 9.9 g (99% yield)
of a colorless liquid was collected. The following spectral properties
were observed: 1H NMR (CDCl3) δ (ppm) 0.84 (s, 3H), 1.23-1.39
(m, 32H), 2.04 (q, 4H), 4.97 (m, 4H), 5.82 (m, 2H); 13C NMR
(CDCl3) δ (ppm) 19.9, 27.3, 27.4, 29.2, 29.4, 29.8, 29.9, 30.0, 30.3,
34.1, 37.3, 37.4, 114.3, 139.4; deuterium-NMR (CDCl3) δ (ppm)
1.38 (s, CH2CD(CH3)CH2). EI/HRMS [M]+ calcd for C24H45D:
335.3662; found 335.3657. Anal. Calcd for C24H45D: 85.89 C, 14.11
H; found 85.92 C, 14.09 H.
Decyanation Using Potassium Metal, Hexamethylphosphora-
mide-d18, and tert-Butanol. Synthesis of 12-Methyltricosa-1,22-
diene (2a). After purification, 9.91 g (99% yield) of a colorless
liquid was collected. The following spectral properties were
observed: 1H NMR (CDCl3) δ (ppm) 0.84 (d, 3H), 1.23-1.39 (m,
33H), 2.04 (q, 4H), 4.97 (m, 4H), 5.82 (m, 2H); 13C NMR (CDCl3)
δ (ppm) 20.0, 27.4, 29.2, 29.4, 29.8, 29.9, 30.0, 30.3, 33.0, 34.1,
37.4, 114.3, 139.4; deuterium-NMR (CDCl3): No signal detected
for CH2CD(CH3)CH2; EI/HRMS [M]+ calcd for C24H46: 334.3600;
J. Org. Chem. Vol. 73, No. 13, 2008 4969

Rojas and Wagener
EI/HRMS [M]+ calcd for C11H22: 154.1722; found 154.1721. Anal.
Calcd for C11H22: 85.63 C, 14.37 H; found 85.61 C, 14.36 H.
Methylcyclohexane (16a). After purification, 42 mg (4% yield)
of a colorless liquid was collected. The following spectral properties
were observed: 1H NMR (CDCl3) δ (ppm) 0.96 (d, 3H), 1.01-1.75
(m, 11H); 13C NMR (CDCl3) δ (ppm) 22.9, 26.5, 26.6, 32.9, 35.6;
EI/HRMS [M]+ calcd for C7H14: 98.1096; found 98.1097. Anal.
Calcd for C7H14: 85.63 C, 14.37 H; found 85.64 C, 14.32 H.
Butylcyclohexane (16b). After purification, 91 mg (9% yield)
of a colorless liquid was collected. The following spectral properties
were observed: 1H NMR (CDCl3) δ (ppm) 0.96 (t, 3H), 1.01-1.8
(m, 17H); 13C NMR (CDCl3) δ (ppm) 14.2, 23.1, 26.6, 26.9, 29.3,
33.6, 37.4, 37.8; EI/HRMS [M]+ calcd for C10H20: 140.1565; found
140.1561. Anal. Calcd for C10H20: 85.63 C, 14.37 H; found 85.60
C, 14.40 H.
Methylcycloheptane (16c). After purification, 0.27 g (28% yield)
of a colorless liquid was collected. The following spectral properties
were observed: 1H NMR (CDCl3) δ (ppm) 0.96 (d, 3H), 1.01-1.4
(m, 12H), 1.65 (m, 1H); 13C NMR (CDCl3) δ (ppm) 21.0, 26.5,
29.3, 34.9, 37.3; EI/HRMS [M]+ calcd for C8H16: 112.1252; found
112.1256. Anal. Calcd for C8H16: 85.63 C, 14.37 H; found 85.59
C, 14.41 H.
Dodec-1-ene (17b). After purification, 0.99 g (99% yield) of a
colorless liquid was collected. The following spectral properties
were observed: 1H NMR (CDCl3) δ (ppm) 0.89 (t, 3H), 1.23-1.39
(m, 16H), 2.04 (q, 2H), 4.97 (m, 2H), 5.82 (m, 1H); 13C NMR
(CDCl3) δ (ppm) 11.1, 22.8, 29.4, 29.7, 29.8, 31.9, 33.9, 114.3,
139.5. EI/HRMS [M]+ calcd for C12H24: 168.1878; found 168.1875.
Anal. Calcd for C12H24: 85.63 C, 14.37 H; found 85.61 C, 14.40
H.
Dec-1-ene (18a). After purification, 0.97 g (97% yield) of a
colorless liquid was collected. The following spectral properties
were observed: 1H NMR (CDCl3) δ (ppm) 0.89 (t, 3H), 1.23-1.39
(m, 12H), 2.04 (q, 2H), 4.97 (m, 2H), 5.82 (m, 1H); 13C NMR
(CDCl3) δ (ppm) 11.1, 22.8, 29.4, 29.7, 29.8, 31.9, 33.9, 114.3,
139.5. EI/HRMS [M]+ calcd for C10H20: 140.1565; found 140.1563.
Anal. Calcd for C10H20: 85.63 C, 14.37 H; found 85.65 C, 14.39
H.
Tridec-1-ene (18b). After purification, 0.98 g (98% yield) of a
colorless liquid was collected. The following spectral properties
were observed: 1H NMR (CDCl3) δ (ppm) 0.89 (t, 3H), 1.23-1.39
(m, 18H), 2.04 (q, 2H), 4.97 (m, 2H), 5.82 (m, 1H); 13C NMR
(CDCl3) δ (ppm) 11.1, 22.8, 29.4, 29.7, 29.8, 31.9, 33.9, 114.3,
139.5. EI/HRMS [M]+ calcd for C13H26: 182.2035; found 182.2033.
Anal. Calcd for C13H26: 85.63 C, 14.37 H; found 85.60 C, 14.42
H.
Butylcycloheptane (16d). After purification, 0.31 g (31% yield)
of a colorless liquid was collected. The following spectral properties
were observed: 1H NMR (CDCl3) δ (ppm) 0.96 (t, 3H), 1.25-1.45
(m, 18H), 1.50 (m, 1H); 13C NMR (CDCl3) δ (ppm) 14.1, 23.1,
26.8, 29.3, 29.7, 34.9, 35.1, 40.4; EI/HRMS [M]+ calcd for C11H22:
154.1722; found 154.1719. Anal. Calcd for C11H22: 85.63 C, 14.37
H; found 85.67 C, 14.31 H.
Acknowledgment. The authors express thanks to Yuki Iseki
at the Petrochemicals Research Laboratory, Sumitomo Chemical
Co., Lisa S. Baugh at ExxonMobil Corporation, the National
Science Foundation (NSF), and the Florida Space Grant
Consortium (NASA-FSGC) for supporting this research.
Non-1-ene (17a). After purification, 0.98 g (98% yield) of a
colorless liquid was collected. The following spectral properties
were observed: 1H NMR (CDCl3) δ (ppm) 0.86 (t, 3H), 1.23-1.39
(m, 10H), 2.04 (q, 2H), 4.97 (m, 2H), 5.82 (m, 1H); 13C NMR
(CDCl3) δ (ppm) 11.1, 22.8, 29.5, 29.8, 31.9, 33.9, 114.3, 139.5.
EI/HRMS [M]+ calcd for C9H18: 126.1409; found 126.1410. Anal.
Calcd for C9H18: 85.63 C, 14.37 H; found 85.67 C, 14.31 H.
Supporting Information Available: Characterization data
1
for compounds 1a-f, 4a,b, and 13a-h. Copies of H and 13C
NMR spectra for compounds 2a-f. This material is available
free of charge via the Internet at http://pubs.acs.org.
JO800640J
4970 J. Org. Chem. Vol. 73, No. 13, 2008