Highly selective hydrogenation of multiple carbon-carbon bonds promoted by nickel(0) nanoparticles

Article abstract of DOI:10.1016/j.tet.2006.10.043

A new method for the highly stereoselective cis semihydrogenation of internal alkynes, semihydrogenation of terminal alkynes, reduction of dienes to alkenes, and reduction of alkynes and alkenes to alkanes is described based on in situ generated both Ni(0) nanoparticles and molecular hydrogen.

Full text of DOI:10.1016/j.tet.2006.10.043

Tetrahedron 63 (2007) 93–102
Highly selective hydrogenation of multiple carbon–carbon bonds
promoted by nickel(0) nanoparticles
y
*
*
Francisco Alonso, I n˜ aki Osante and Miguel Yus
Departamento de Quı ´m ica Org aꢀ nica, Facultad de Ciencias and Instituto de Sı ´n tesis Org aꢀ nica (ISO), Universidad de Alicante,
Apdo. 99, 03080 Alicante, Spain
Received 3 October 2006; accepted 18 October 2006
Available online 3 November 2006
This paper is dedicated to Professor D. A. Evans on the occasion of his 65th anniversary
Abstract—A new method for the highly stereoselective cis semihydrogenation of internal alkynes, semihydrogenation of terminal alkynes,
reduction of dienes to alkenes, and reduction of alkynes and alkenes to alkanes is described based on in situ generated both Ni(0) nanoparticles
and molecular hydrogen.
Ó 2006 Elsevier Ltd. All rights reserved.
1
. Introduction
Concerning the cis semireduction of alkynes and that of
terminal alkynes, Lindlar catalyst, trialkylammonium for-
4
5
The selective transformation of hydrocarbons with multiple
carbon–carbon bonds (i.e., alkynes and dienes) to monoole-
fins is of fundamental importance both in laboratory practice
and fine chemicals production. It is also a crucial step in
industrial polymerization processes with the aim of the com-
plete elimination of alkynes and dienes from alkene feed-
stocks. Heterogeneous catalytic hydrogenation continues
to be the most useful technique for the addition of molecular
hydrogen to carbon–carbon double and triple bonds, parti-
cularly if the objective involves chemo-, regio-, and stereo-
mates under palladium catalysis, complex reducing agents
of the type NaH–NaOR–MX , and dispersed nickel on
graphite, are some of the formerly utilized reducing sys-
6
n
7
tems, but not always leading to an optimum selectivity. In
fact, partial isomerization of the (Z)-alkene to the (E)-
alkene, shift of the double bond, overreduction to the alkane,
and problems with reproducibility were observed, especially
in Lindlar’s catalyst. In the more recent literature, noteworthy
is the higher selectivity achieved with a montmorillonite-
8
supported complex, nickel boride or palladium catalysts
on borohydride exchange resin, a homogeneous palla-
dium(0) catalyst, palladium on pumice, or using a variant
1
9
selectivities. In particular, the semihydrogenation of the
1
0
11
carbon–carbon triple bond is a very valuable reaction in syn-
thetic organic chemistry. The difficulty to control the stereo-
chemistry and to minimize the formation of overreduced
products make it a challenging transformation. In the last
decades, different general methods have been developed
for this purpose and applied depending on the stereochemis-
try desired for the final product, including: (a) heterogeneous
1
2
of Lindlar’s catalyst. At any rate, most of the above men-
tioned methods are not general but applied to a specific
type of substrate. Therefore, any new and efficient method
for the semihydrogenation of alkynes is welcome.
Selective reduction of dienes was accomplished by hetero-
geneous catalytic hydrogenation with Pd supported on
poly(N-vinyl-2-pyrrolidone) in methanol, Pd/CaCO or Pd
1
a
catalytic hydrogenation, (b) homogeneous catalytic hydro-
genation, and (c) non-catalytic chemical methods (e.g.,
2
3a
3
3
b
3c,d
1a
reduction by diimide, dissolving metals,
metal species, hydroalumination, or metal hydride–tran-
low-valent
black in the presence of phenylacetaldehyde, by homoge-
neous catalytic hydrogenation with a variety of transition-
3
e
3f
3
g
2
sition-metal halide combinations ).
metal complexes, by alkali metals (for conjugated
dienes), or more recently by SmI /H O/amine.
1
3
14
2
2
Keywords: Alkynes; Dienes; Alkenes; Nickel nanoparticles; Selective
hydrogenation.
For the reduction of alkenes to alkanes heterogeneous cata-
lytic hydrogenation is preferred due to the mild reaction
1
*
Corresponding authors. Fax: +34 965 903549; e-mail addresses:
falonso@ua.es; yus@ua.es
conditions mostly required and the easy separation of the
catalyst. Among the many catalysts available, nickel cata-
y
Current address: Instituto de Qu ´ı mica Org ꢀa nica General, Consejo Supe-
rior de Investigaciones Cient ´ı ficas (CSIC), Juan de la Cierva, 3, 28006
Madrid, Spain.
1
5
lysts are universal and widely used both in the laboratory
and in industry. However, Raney nickel is probably by far
0
040–4020/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2006.10.043

94
F. Alonso et al. / Tetrahedron 63 (2007) 93–102
the most used nickel catalyst because of its high activity, be-
Concerning the semihydrogenation of internal alkynes
(Table 1), symmetrical dialkyl substituted alkynes (Table 1,
entries 1 and 3) as well as cyclooctyne (Table 1, entry 5)
were reduced to the corresponding alkenes with excellent
conversions and yields and with exclusive cis stereochemis-
try. Several hydroxyalkyl substituted internal alkynes were
also successfully converted into the corresponding cis-
olefins (Table 1, entries 6–8). It is noteworthy that even
the more labile and prone-to-isomerization oct-2-en-1-ol
was obtained in a 93:7 Z/E diastereomeric ratio without
any trace of the isomerized byproduct octanal (Table 1,
entry 8). Alkynes bearing an alkoxy moiety (Table 1,
entries 10, 12, and 13) were nicely semireduced, the reac-
tion conditions being compatible with the presence of the
benzyloxy group, which did not undergo hydrogenolysis.
Furthermore, several propargylic amines could be also
transformed into the corresponding cis-allylic amines with
high conversions and isolated yields (Table 1, entries 14–
16). The stereochemistry in all the products was confirmed
by NOESY experiments.
1
6
ing able to reduce practically any function. Its main disad-
vantages are: (a) the difficulty in calculating the dosage (it is
usually measured as a suspension rather than by weight); (b)
ferromagnetic properties that preclude the use of magnetic
stirring; (c) it is potentially hazardous (pyrophoric); (d) it be-
comes inactive after prolonged storage, presumably because
it loses hydrogen slowly.
On the other hand, we have recently reported the fast
synthesis of nickel(0) nanoparticles with diameters of
2
with lithium powder and a catalytic amount of DTBB (4,4 -
.5ꢀ1.5 nm by reduction of anhydrous nickel(II) chloride
0
1
7
di-tert-butylbiphenyl) in THF at room temperature. The
high reactivity of these nanoparticles was demonstrated in
the catalytic hydrogenation of a variety of organic com-
pounds, including carbon–carbon multiple-bond-containing
1
8,19
compounds.
Moreover, similar reduction systems to
NiCl –Li–DTBB(cat.) such as NiCl –Li–copolymer(cat.),
2
0
2
2
1
9
NiCl $2H O–Li–DTBB(cat.),
2
EtOH, or NiCl –Li–copolymer(cat.)–EtOH, also generate
2
nanosized metallic nickel with demonstrated or potential
applicability in organic chemistry. We have recently com-
municated that the introduction of an alcohol (ethanol or
isopropanol) as a source of hydrogen in the reducing system
NiCl –Li–DTBB(cat.)–
2
2
2
0
2
1
18b,24
Alternatively, a polymer-supported arene, prepared by
radical copolymerization of 4-vinylbiphenyl and divinyl-
2
4b
benzene (mixture of regioisomers),
was utilized as an
electron carrier instead of DTBB. Very similar results were
obtained with this copolymer in the reduction of oct-4-yne
and dec-5-yne (Table 1, entries 2 and 4, respectively), though
the reaction times were longer due to its lower solubility in
the reaction medium. In the case of 1-methoxydec-3-yne,
however, a clear improvement in both the conversion and
isolated yield was observed (compare entries 10 and 11 in
Table 1). Nonetheless, by using the copolymer instead of
DTBB the work-up was easier, since the arene is removed
by simple filtration, and cleaner reaction crudes were ob-
tained in all cases.
[
i.e., NiCl –Li–DTBB(cat.)–ROH] is a very convenient
2
method for the highly stereoselective cis semihydrogenation
of internal alkynes and the semihydrogenation of terminal
2
2
alkynes under mild reaction conditions. One of the main
advantages of this methodology is that the handling of exter-
nal molecular hydrogen is avoided since it is generated in
situ in the reaction flask.
2
. Results and discussion
2
.1. Semihydrogenation of internal alkynes
2
.2. Semihydrogenation of terminal alkynes
In a previous study, we applied the system composed of
NiCl $2H O–Li–arene(cat.) to the reduction of alkynes.
The above methodology also found application in the gener-
ally less studied and more difficult to control semihydro-
genation of terminal alkynes. In this case, i-PrOH showed
to be more effective than EtOH as a hydrogen source.
Thus, a variety of terminal alkynes bearing alkyl, alkoxy-
alkyl, and arylaminoalkyl substituents were reduced to the
corresponding terminal alkenes in good yields albeit with
variable amounts of the overreduced alkanes (10–15%)
2
2
A variety of substrates could be completely reduced to the
corresponding alkanes, whereas the semihydrogenation re-
action could be only controlled in a few cases without a gen-
2
3
eral product stereochemistry. The more versatile system,
NiCl –Li–DTBB(cat.)–EtOH was applied to a wide range
2
of internal alkynes with a high selectivity and under very
mild reaction conditions (Scheme 1 and Table 1). The role
of the different components of the reducing system men-
tioned above is as follows: (a) nickel(II) chloride is the
source of Ni(0) nanoparticles, (b) lithium has got a double
role, the reduction of Ni(II) to Ni(0) and the in situ genera-
tion of molecular hydrogen by reaction with the alcohol,
(
Table 2). It is worthy to note that also in this case, the
benzyloxy group remained untouched under the reaction
conditions (Table 2, entry 3).
2
.3. Complete hydrogenation of alkynes
(
c) DTBB is used in catalytic amounts and acts as an electron
The versatility of this reducing system was demonstrated in
the complete hydrogenation of both internal and terminal
alkynes (Table 3). In this case, EtOH was used as the hydro-
gen source in the presence of a 4-vinylbiphenyl/divinyl-
benzene copolymer as an electron carrier. By using a slight
excess of lithium and EtOH (i.e., to generate 2.5 equiv of
molecular hydrogen), diphenylacetylene and diphenyltri-
methylsilylacetylene were transformed into 1,2-diphenyl-
ethane and trimethylphenethylsilane in high yields and
short reaction times (Table 3, entries 1 and 2, respectively).
The latter could be also obtained in high yield by using
carrier from lithium to nickel(II) chloride, and (d) EtOH is
the source of hydrogen.
NiCl -Li-DTBB(cat.)-EtOH
2
Ni(0) nanoparticles-H2
THF, room temperature
R1
R2
R1
R2
Scheme 1.

F. Alonso et al. / Tetrahedron 63 (2007) 93–102
Table 1. Selective semihydrogenation of internal alkynes
95
a
b
c
Entry
Starting alkyne
t (h)
Product
Conversion (%)
Yield (%)
d
1
n-Pr
n-Pr
n-Bu
n-Bu
n-Pr
n-Pr
n-Bu
n-Bu
2
100
99
n-Pr
n-Pr
n-Pr
n-Bu
n-Bu
e
d
99
2
3
4
5
6
7
8
9
24
100
100
100
100
100
100
77
n-Pr
n-Bu
n-Bu
d
98
4
e
d
99
24
d
95
3
8
Et
OH
d
83
OH
Et
n-Hex
n-Pent
OH
4
62
OH
n-Hex
f
65 (96 )
d
24
n-Pent
OH
OH
g
d
97
MeO
OMe
4
84
MeO
OMe
n-Hex
OMe
OMe
10
11
12
13
14
15
2
92
85
93
73
79
90
87
OMe
OMe
n-Hex
n-Hex
Me
n-Hex
Me
e,g
24
24
2
100
100
100
83
OBn
OBn
Et
OBn
OBn
NEt2
NEt2
Et
n-Hex
n-Oct
7
n-Hex
NEt2
8
100
n-Oct
NEt2
Ph
16
7
100
94
Ph
NEt2
NEt2
a
b
c
Reaction carried out at room temperature with EtOH as the hydrogen source and DTBB as electron carrier, unless otherwise stated.
Conversion determined by analytical GLC.
Isolated yield of the olefin after column chromatography [silica gel (entries 7, 8, and 10–13) or neutral alumina (entries 14–16), hexane or hexane/EtOAc],
unless otherwise stated. For conversions lower than 100% the corresponding yield refers to the amount of starting material converted.
Yield determined using analytical GLC and n-dodecane as an internal standard.
d
e
f
Reaction carried out with a 4-vinylbiphenyl/divinylbenzene copolymer as an electron carrier.
Z/E¼93:7.
g
ꢁ
Reaction performed at 0 C.
DTBB instead of the supported copolymer. However, purifi-
cation by column chromatography of the resulting mixture
was necessary with DTBB, whereas the reaction crude
obtained with the supported copolymer was pure enough
not requiring any further purification. Other internal alkynes,
such as those bearing a dialkylaminomethyl and carboxy

96
F. Alonso et al. / Tetrahedron 63 (2007) 93–102
Table 2. Selective semihydrogenation of terminal alkynes
2.4. Semihydrogenation of dienes
a
b
Conversion (%) Yield (%)
c
Entry Starting alkyne t (h)
Product
The good results obtained in the semihydrogenation of
alkynes prompted us to study the possible selectivity of the
reducing system in the semihydrogenation of dienes. Thus,
both the isolated diene cycloocta-1,5-diene and the conju-
gated one cyclohepta-1,3-diene were selectively reduced
in excellent yields to the corresponding cycloalkenes at
room temperature, using EtOH as the hydrogen source and
DTBB as the electron carrier (Table 4, entries 1 and 2,
respectively). High selectivity was also observed in the
reduction of dicyclopentadiene, where only one of the two
disubstituted carbon–carbon double bonds was reduced
1
2
3
4
n-Hex
24
24
7
n-Hex
100
100
79
85
85
74
87
n-Oct
n-Oct
BnO
BnO
d
24
Ph
87
(
Table 4, entry 3). In this case, the use of the copolymer as
Ph
an electron carrier slightly improved the yield but the cleaner
reaction crude did not need any further purification (Table 4,
entry 4). Selective reduction of the exocyclic carbon–carbon
double bond of (R)-(+)-limonene furnished (R)-(+)-p-
menth-1-ene in high yield, independent of the electron
carrier used (Table 4, entries 5 and 6).
H
N
H
N
d
79
5
24
100
Ph
Ph
a
Reaction carried out at room temperature with i-PrOH as the hydrogen
source and DTBB as the electron carrier, unless otherwise stated.
Conversion determined by analytical GLC.
Yield determined using analytical GLC and n-dodecane as an internal
standard, unless otherwise stated.
Isolated yield of the olefin after column chromatography (silica gel,
hexane/EtOAc). For conversions lower than 100% the corresponding
yield refers to the amount of starting material converted.
b
c
d
2.5. Hydrogenation of alkenes
Finally, and in order to complete this study on the hydro-
genation of multiple carbon–carbon bonds, we explored the
reduction of a variety of alkenes, including a diene, to the
corresponding alkanes (Table 5). Stilbene and 1,4-diphenyl-
buta-1,3-diene were reduced to the corresponding alkanes in
high yields using EtOH as the hydrogen source and DTBB as
the electron carrier (Table 5, entries 1 and 3). Once again,
higher yields were obtained when using the copolymer as
groups, were also completely reduced in high yields (Table
, entries 4 and 5). A tertiary propargylic alcohol and hex-
-ynoic acid are some examples of the effective reduction
of terminal alkynes to the corresponding alkanes (Table 3,
entries 6 and 7).
3
6
Table 3. Complete hydrogenation of alkynes
a
b
Entry
Starting alkyne
t (h)
Product
Yield (%)
Ph
1
Ph
Ph
2
99
Ph
c
2
3
4
5
6
Ph
SiMe3
SiMe3
3
SiMe3
93
Ph
d
5
SiMe3
Ph
92
99
Ph
12
12
12
NEt2
NEt2
CO H
d
2
CO2H
93
OH
OH
95
CO H
d
95
2
CO H
7
12
2
a
Reaction carried out at room temperature with EtOH as the hydrogen source and a 4-vinylbiphenyl/divinylbenzene copolymer as electron carrier, unless other-
wise stated.
Isolated yield of the alkane after column chromatography [silica gel (entries 1, 3, and 6) or neutral alumina (entry 4), hexane or hexane/EtOAc], unless other-
wise stated.
Isolated yield from the reaction crude.
Reaction carried out with DTBB as an electron carrier.
b
c
d

F. Alonso et al. / Tetrahedron 63 (2007) 93–102
Table 5. Hydrogenation of alkenes
97
Table 4. Selective semihydrogenation of dienes
a
b
a
b
Entry
Starting diene
t (h)
Product
Yield (%)
Entry
Starting alkene
t (h)
Product
Yield (%)
Ph
Ph
Ph
1
24
95
1
7
96
Ph
Ph
Ph
Ph
c
Ph
d
99
2
3
4
5
6
7
12
2
3
4
5
21
22
99
Ph
Ph
Ph
5
96
Ph
Ph
Ph
Ph
H
H
c
c
d
99
Ph
88
4
H
H
H
H
1
99
d
20
e
90
H
H
e
CO2Et 24
CO2Et 86
e
22
99
CO Et
CO Et
2
2
24
12
79
OH
OH
8
99
d
20
c
92
6
a
Reaction carried out at room temperature with EtOH as the hydrogen
source and DTBB as electron carrier, unless otherwise stated.
Isolated yield of the alkene after column chromatography (silica gel,
hexane or hexane/EtOAc).
Reaction carried out with a 4-vinylbiphenyl/divinylbenzene copolymer as
the electron carrier.
Isolated yield from the reaction crude.
b
c
a
Reaction carried out at room temperature with EtOH as the hydrogen
source and DTBB as the electron carrier, unless otherwise stated.
Yield determined using analytical GLC and n-dodecane as an internal
standard, unless otherwise stated.
Isolated yield of the alkene after column chromatography (silica gel,
hexane).
Reaction carried out with a 4-vinylbiphenyl/divinylbenzene copolymer as
the electron carrier.
Isolated yield from the reaction crude.
b
c
d
e
d
e
Yield determined using analytical GLC and n-dodecane as an internal
standard.
and NiCl $2H O–Li–arene systems since it is more selective
2
2
in the semihydrogenation of alkynes and more compatible
with the presence of a variety of functional groups.
an electron carrier together with simpler product purification
Table 5, entries 2 and 4). As an example of an isolated
(
alkene, cyclododecene was quantitatively reduced to cyclo-
dodecane in a short reaction time (Table 5, entry 5). In gen-
eral, longer reaction times were needed for the reduction
of the functionalized alkenes (E)-ethyl hex-3-enoate, ethyl
hept-6-enoate, and o-allylphenol, which also proceeded
with a good performance.
4. Experimental
4.1. General
NMR spectra were recorded on a Bruker Avance 300 and
Bruker Avance 400 (300 and 400 MHz for H NMR, and
1
1
3
7
5 and 100 MHz for C NMR, respectively) using CDCl3
3
. Conclusion
as solvent and TMS as internal standard; chemical shifts
are given in d (ppm) and coupling constants (J) in hertz.
Mass spectra (EI) were obtained at 70 eV on a Shimadzu
QP-5000 and Agilent 5973 spectrometers, fragment ions
are given in m/z with relative intensities (%) in parenthesis.
HR-MS analyses were carried out on a Finnigan MAT95S
spectrometer. Determination of the purity of volatile com-
pounds and chromatographic analyses (GLC) were per-
formed with a Hewlett Packard HP-5890 instrument
equipped with a flame ionization detector and a 30 m capil-
In summary, the in situ generated both Ni(0) nanoparticles
and molecular hydrogen from the system NiCl –Li–
2
DTBB–ROH is a new mild and simple methodology for
the efficient stereoselective cis semihydrogenation of al-
kynes. This methodology has also found application in the
semihydrogenation of terminal alkynes and dienes, as well
as in the reduction of alkynes and alkenes to alkanes. The
use of a polymer-supported arene as the electron carrier in-
stead of DTBB represents a clear advantage making the
work-up simpler and providing, in general, higher yields
and cleaner reaction crudes. The above system is more ad-
vantageous than the previously reported NiCl –Li–arene–H
lary column (0.32 mm diameter, 0.25 mm film thickness),
using nitrogen (2 mL/min) as carrier gas, T
ꢁ
¼275 C,
injector
ꢁ
ꢁ
ꢁ
Tcolumn¼60 C (3 min) and 60–270 C (15 C/min), using
n-dodecane as an internal standard. Flash column
2
2

98
F. Alonso et al. / Tetrahedron 63 (2007) 93–102
chromatography was performed using silica gel 60 of 40–
0 mm. THF was directly used without any purification
Acros, 99.9%). Anhydrous nickel chloride (Aldrich) and
159 (51), 146 (3), 145 (4), 131 (4), 130 (2), 129 (13), 128
(3), 105 (5), 92 (8), 91 (100), 89 (3), 77 (3), 67 (3), 65
(12), 63 (2), 53 (3), 51 (3); HR-MS: calcd for C H O:
6
(
1
2 14
lithium powder were (MEDALCHEMY S. L.) commercially
available.
174.1045; found: 174.1006.
2
9
4
.2.3. 1-Benzyloxyhex-3-yne (Table 1, entry 13). Yield:
1
Alkynes in entries 1–4 and 6–9 in Table 1, 1, 2, 4 in Table
83%; H NMR (300 MHz, CDCl ): d¼1.11 (t, J¼7.5 Hz,
3
2
, 1–3, 5–7 in Table 3, all dienes in Table 4, and all alkenes
in Table 5 were commercially available. Alkynes in entries
0–13 in Table 1, 3 and 5 in Table 2 were obtained by stan-
3H, CH ), 2.11–2.20 (m, 2H, CH CH ), 2.43–2.49 (m, 2H,
3
2
3
CH CH O), 3.55 (t, J¼7.1 Hz, 2H, CH CH O), 4.54 (s,
2
2
2
2
1
3
1
2H, CH Ph), 7.23–7.34 (m, 5H, 5ꢂArH); C NMR
2
dard alkylation reactions from the starting alcohols (see
below) and aniline. Cyclooctyne (Table 1, entry 5) was pre-
pared by bromination of cyclooctene followed by two suc-
(75 MHz, CDCl ): d¼12.3 (CH CH ), 14.1 (CH ), 20.1
3
2
3
3
(CH CH O), 68.8, 72.8 (CH CH OBn, CH Ph), 75.9
2
2
2
2
2
(CH CH C^C), 82.7 (CH CH C^C), 127.5, 127.6,
3
2
3
2
2
5
cessive dehydrobrominations with KO-t-Bu and LDA.
The diethylaminomethyl alkynes (entries 14–16) were pre-
128.3, 138.2 (6ꢂArC); IR (film): n¼3087, 3063, 3029,
ꢃ1
736, 698 (HC]C), 1454 (C^CCH ), 1104 (C–O) cm
2
;
2
6
+
pared following literature procedures (see below). The
-vinylbiphenyl/divinylbenzene copolymer was prepared
by radical copolymerization of the corresponding mono-
MS (EI): m/z (%)¼187 (M ꢃ1, 2), 173 (5), 160 (7), 159
(60), 145 (2), 143 (3), 131 (2), 130 (2), 129 (14), 128 (3),
105 (5), 92 (8), 91 (100), 89 (2), 79 (3), 77 (3), 67 (3), 65
(11), 63 (2), 53 (2), 51 (3); HR-MS: calcd for C H O:
4
2
7
mers according to the published procedure.
1
3 16
1
88.1201; found: 188.1154.
4.2. Preparation of the starting acetylenic methyl and
benzyl ether derivatives. General procedure
4.2.4. 3-Benzyloxypent-1-yne (Table 2, entry 3). Yield:
1
8
3H, CH ), 1.73–1.83 (m, 2H, CH CH ), 2.45 (s, 1H,
5%; H NMR (300 MHz, CDCl ): d¼1.01 (t, J¼7.4 Hz,
3
The corresponding alcohol (1 mmol) was added to a white
suspension of NaH (3 mmol) in THF (10 mL) at room
temperature under argon. After stirring for 30 min, methyl
iodide or benzyl bromide (3 mmol) was added and the
reaction was monitored by GLC. Then, the resulting mixture
was quenched with water (10 mL) and extracted with CHCl3
3 2 3
HC^C), 4.01 (t, J¼6.4 Hz, 1H, CHO), 4.49, 4.80 (AB sys-
tem, J¼11.8 Hz, 2H, CH O), 7.24–7.37 (m, 5H, 5ꢂArH);
2
1
3
C
(CH CH ), 69.6 (CHO), 70.4 (CH O), 73.8 (C^CH), 82.7
NMR (75 MHz, CDCl ): d¼9.5 (CH ), 28.7
3
3
2
3 2
(HC^C), 127.6, 127.9, 128.3, 137.9 (6ꢂArC); IR (film):
(
Na SO and the solvent evaporated (15 Torr) to give an
3ꢂ10 mL). The organic phase was dried with anhydrous
n¼3299 (HC^C), 3088, 3064, 3031, 737, 698 (HC]C),
ꢃ1
1069 (C–O) cm ; MS (EI): m/z (%)¼145 (7), 144 (3),
2
4
oil. Purification by flash column chromatography (silica
gel, hexane) afforded the corresponding alkylated products.
New compounds or those for which spectroscopic data have
not been found or are incomplete, follow.
117 (3), 107 (10), 105 (5), 92 (28), 91 (100), 79 (8), 77
(8), 67 (3), 65 (10), 51 (4); HR-MS: calcd for C H O:
174.1045; found: 174.1018.
1
2 14
4
.3. Synthesis of the starting acetylenic diethylamino
derivatives. General procedure
2
8
26
4
9
3
2
3
.2.1. 1-Methoxydec-3-yne (Table 1, entry 10). Yield:
7%; H NMR (300 MHz, CDCl ): d¼0.89 (t, J¼6.8 Hz,
1
3
H, CH ), 1.21–1.52 [m, 8H, (CH ) CH ], 2.12–2.16,
3
In a round-bottomed flask fitted with a reflux condenser di-
ethylamine (10.4 mL, 7.3 g) was added in three portions at
room temperature over a solution of paraformaldehyde
(0.1 mol, 3 g) in dioxane (25 mL). The temperature of the
3
2 4
.40–2.45 [2m, 4H, CH (CH ) CH , CH CH O], 3.37 (s,
2
2 4
3
2
2
1
3
H, CH O), 3.47 (t, J¼7.0 Hz, 2H, CH O); C NMR
3
2
(
2
75 MHz, CDCl ): d¼13.9 (CH ), 18.7, 19.9, 22.5, 28.5,
3
3
ꢁ
8.9, 31.3 [(CH ) CH , CH CH O], 58.5 (CH O), 71.3
3
mixture rose gradually to 45 C after each addition. Thus, af-
2
5
2
2
2
(
(
CH O), 76.4 [C^C(CH ) O], 81.3 [C^C(CH ) O]; IR
2
ter cooling to room temperature a second portion of diethyl-
amine was added. When the ensuing exothermic reaction
had subsided, the last portion was added. The conversion
2 2
2 2
ꢃ1
film): n¼1459 (C^CCH ), 1119 (C–O) cm ; MS (EI):
2
+
m/z (%)¼167 (M ꢃ1, 1), 153 (11), 125 (24), 123 (11), 121
ꢁ
(
(
21), 112 (10), 111 (22), 108 (12), 107 (47), 101 (14), 99
13), 98 (29), 97 (100), 95 (23), 94 (19), 93 (58), 91 (22),
was completed by heating the mixture for 30 min at 50 C.
The reaction mixture was cooled to room temperature and
CuBr (4.6 mmol, 660 mg) was added. Then, the mixture
8
(
6
5 (15), 84 (10), 83 (68), 82 (10), 81 (47), 80 (20), 79
79), 77 (27), 72 (11), 71 (11), 69 (28), 68 (96), 67 (73),
6 (17), 65 (18), 55 (30), 53 (21), 52 (15), 51 (11); HR-
MS: calcd for C H O: 168.1514; found: 168.1495.
ꢁ
was heated at 85 C and the corresponding acetylene
(0.1 mol) was added in portions over 30 min. The reaction
mixture was cooled to room temperature after an additional
period of 2–2.5 h. In all cases the reaction mixture was
1
1 20
29
4
9
3
.2.2. 5-Benzyloxypent-2-yne (Table 1, entry 12). Yield:
1%; H NMR (300 MHz, CDCl ): d¼1.76 (t, J¼2.5 Hz,
poured into 500 mL of water and extracted with Et O
2
1
(3ꢂ40 mL). The organic phase was dried with anhydrous
3
H, CH ), 2.39–2.46 (m, 2H, CH CH O), 3.53 (t,
3
Na SO and concentrated in vacuo (15 Torr). The resulting
4
2
2
2
J¼7.0 Hz, 2H, CH CH O), 4.52 (s, 2H, CH Ph), 7.24–
residue was purified by flash column chromatography (silica
gel, hexane) affording the corresponding acetylenes. New
compounds or those for which spectroscopic data have not
been found, follow.
2
2
2
1
3
7
.33 (m, 5H, 5ꢂArH); C NMR (75 MHz, CDCl ): d¼3.3
3 2 2 2 2 2
3
(
CH ), 20.0 (CH CH O), 68.7, 72.7 (CH CH O, CH Ph),
7
1
7
5.7, 76.5 (CH C^CCH , CH C^CCH ), 127.4, 127.5,
3 2 3 2
28.2, 138.1 (6ꢂArC); IR (film): n¼3087, 3063, 3029,
ꢃ1
30
37, 698 (HC]C), 1454 (C^CCH ), 1104 (C–O) cm
2
;
4.3.1. N,N-Diethylnon-2-yn-1-amine (Table 1, entry 14).
Yield: 91%; H NMR (300 MHz, CDCl ): d¼0.89 (t,
+
+
1
MS (EI): m/z (%)¼174 (M , 1), 173 (M ꢃ1, 5), 160 (6),
3

F. Alonso et al. / Tetrahedron 63 (2007) 93–102
99
J¼6.7 Hz, 3H, CH CH CH ), 1.06 (t, J¼7.2 Hz, 6H,
Table 1 or neutral alumina, hexane/EtOAc 8:2 for entries
14–16 in Table 1) to give the corresponding alkenes. For vol-
atile products, the dried organic layer was analyzed by GLC
using n-dodecane as an internal standard. cis-Hex-3-ene-1-
ol, oct-1-ene, dec-1-ene, 4-phenylbut-1-ene, and N-allylani-
line were characterized by comparison of their physical and
spectroscopic data with those of commercially available sam-
ples (Aldrich). The products cis-oct-4-ene, cis-dec-5-ene,
and cis-1,2-dimethoxyethene were characterized by compar-
ison of their physical and spectroscopic data with those of
authentic samples prepared by semihydrogenation using
3
2
2
2
ꢂCH CH N), 1.13–1.54 [m, 8H, (CH ) CH ], 2.16–2.20
3
2
2 4
3
[
2
m, 2H, CH C^CH N], 2.52 (q, J¼7.2 Hz, 4H,
2 2
1
3
ꢂNCH CH ), 3.38 (t, J¼2.0 Hz, 2H, C^CH N);
C
2
3
2
NMR (75 MHz, CDCl ): d¼12.4 (2ꢂCH CH N), 13.8
3
3
2
(
CH CH CH ), 18.5, 22.4, 28.4, 28.8, 31.2 [(CH ) CH ],
3 2 2 2 5 3
4
8
0.8 (C^CCH N), 46.9 (2ꢂNCH CH ), 74.1 (C^CCH N),
ꢃ1
2 2
2
2
3
2
4.7 (C^CCH N); IR (film): n¼1463 (C^CCH ) cm
;
+
+
MS (EI): m/z (%)¼195 (M , 6), 194 (M ꢃ1, 4), 181 (13),
80 (100), 112 (2), 108 (2), 86 (3), 81 (7), 79 (3), 77 (2), 67
3), 58 (7), 56 (2), 55 (2), 53 (2); HR-MS: calcd for
C H N: 195.1987; found: 195.1987.
1
(
4
b
Lindlar catalyst. New products or those for which spectro-
scopic data have not been found or are incomplete, follow.
1
3 25
4
1
.3.2. N,N-Diethylundec-2-yn-1-amine (Table 1, entry
5). Yield: 93%; H NMR (300 MHz, CDCl ): d¼0.88 (t,
3
1
1
32
4.4.1. (Z)-Dec-3-en-1-ol (Table 1, entry 7). Yield: 62%;
H NMR (300 MHz, CDCl ): d¼0.88 (t, J¼6.6 Hz, 3H,
3
1
J¼6.7 Hz, 3H, CH ), 1.06 (t, J¼7.2 Hz, 6H, 2ꢂCH CH N),
3
3
2
3
1
.28–1.52 [m, 12H, (CH ) CH ], 2.16–2.18 (m, 2H,
6
CH ), 1.22–1.50 [m, 8H, (CH ) CH ], 1.70 (s, 1H, OH),
3
2
3
3
2 4
CH C^CCH N), 2.53 (q, J¼7.2 Hz, 4H, 2ꢂNCH CH ),
2.06 (td, J¼6.8, 6.6 Hz, 2H, CH (CH ) CH ), 2.33 (td,
2
2
2
3
2
2 4
3
1
3
3
1
2
4
.38 (s, 2H, C^CCH N); C NMR (75 MHz, CDCl ): d¼
J¼6.6, 6.5 Hz, 2H, CH CH OH), 3.64 (td, J¼5.8, 5.7 Hz,
2
3
2 2
2.4 (2ꢂCH CH N), 13.9 (CH CH CH ), 18.5, 22.5, 28.7,
2H, CH OH), 5.32–5.40 (m, 1H, HC]CHCH CH OH),
2
3
2
3
2
2
2
2
1
3
8.9, 29.0, 29.1, 31.7 [CH (CH ) ], 40.8 (C^CCH N),
2 7
5.52–5.61 (m, 1H, CH]CHCH CH OH);
2
C NMR
(75 MHz, CDCl ): d¼14.0 (CH ), 22.6, 27.3, 28.9, 29.6,
3
2
2
7.0 (2ꢂNCH CH ), 74.2 (C^CCH N), 84.7 (C^CCH N);
2
3
2
2
3
3
ꢃ1
IR (film): n¼1463 (C^CCH ) cm ; MS (EI): m/z (%)¼
30.8, 31.7 [(CH ) , CH CH OH], 62.3 (CH OH), 124.9
2 5 2 2 2
2
+
+
2
8
23 (M , 5), 222 (M ꢃ1, 4), 209 (15), 208 (100), 95 (2),
(CH]CHCH CH OH), 133.5 (CH]CHCH CH OH); IR
2 2 2 2
ꢃ1
6 (2), 81 (3), 79 (2), 67 (3), 58 (5), 56 (2), 55 (2); HR-MS:
(film): n¼3373 (OH), 3009 (HC]CH), 1048 (C–O) cm
;
+
calcd for C H N: 223.2300; found: 223.2298.
15 29
MS (EI): m/z (%)¼138 (M ꢃ18, 7), 110 (16), 109 (17), 96
(
26), 95 (35), 83 (26), 82 (51), 81 (79), 79 (13), 77 (3), 71
4
.3.3. N,N-Diethyl-5-phenylpent-2-yn-1-amine (Table 1,
(12), 70 (17), 69 (52), 68 (100), 67 (82), 66 (8), 65 (5), 58
(2), 57 (25), 56 (24), 55 (93), 54 (40), 53 (15), 51 (2); HR-
1
entry 16). Yield: 85%; H NMR (300 MHz, CDCl3):
d¼1.03 (t, J¼7.2 Hz, 6H, 2ꢂCH CH ), 2.47 (q, J¼7.2 Hz,
+
MS: calcd for C H O: 156.1514, 138.1671 (M ꢃH O);
3
2
10 20
2
4
H, 2ꢂCH CH ; t, J¼7.5 Hz, 2H, CH Ph), 2.81 (t,
found: 138.1431.
2
3
2
J¼7.5 Hz, 2H, CH CH Ph), 3.34 [d, J¼2.0 Hz, 2H,
2
2
1
3
33
CH N(CH CH ) ], 7.17–7.30 (m, 5H, 5ꢂArH); C NMR
4.4.2. (Z)-Oct-2-en-1-ol (Table 1, entry 8). Yield: 65%;
H NMR (300 MHz, CDCl ): d¼0.89 (t, J¼6.8 Hz, 3H,
2
2
3 2
1
(
(
75 MHz, 20.7
CH CH Ph), 35.3 (CH Ph), 40.8 [CH N(CH CH ) ], 46.9
CDCl ):
d¼12.5
(2ꢂCH CH ),
3
3
2
3
CH ), 1.21–1.41 [m, 6H, (CH ) CH ], 1.51 (s, 1H, OH),
3
2
2
2
2
2
3 2
2 3
3
(
1
3
2ꢂCH CH ), 75.1 (C^CCH N), 84.0 (C^CCH N),
2.07 (td, J¼6.9, 6.8 Hz, 2H, CH (CH ) CH ), 4.20 (d,
2
3
2
2
2
2 3
3
1
3
26.1, 128.2, 128.4, 140.7 (6ꢂArC); IR (film): n¼3086,
J¼5.6 Hz, 2H, CH OH), 5.50–5.73 (m, 2H, CH]CH);
C
2
ꢃ1
063, 3027 (HC]C), 1454 (C^CCH ) cm ; MS (EI):
2
NMR (75 MHz, CDCl ): d¼14.0 (CH ), 22.5, 27.4, 29.2,
3
3
+
+
m/z (%)¼215 (M , 7), 214 (M ꢃ1, 5), 201 (17), 200
100), 142 (2), 141 (4), 129 (5), 128 (26), 127 (4), 115 (7),
08 (3), 92 (3), 91 (31), 65 (5), 58 (8), 56 (4), 51 (2); HR-
MS: calcd for C H N: 215.1674; found: 215.1677.
31.4 [(CH ) ], 58.5 (CH OH), 128.2 (CH]CHCH OH),
2 4 2 2
(
1
133.3 (CH]CHCH OH); IR (film): n¼3357 (OH), 3014,
2
ꢃ1
758 (HC]C), 1119 (C–O) cm ; MS (EI): m/z (%)¼111
+
+
(M ꢃ17, 2), 110 (M ꢃ18, 21), 95 (12), 85 (7), 84 (4), 83
1
5 21
(
3), 82 (22), 81 (35), 79 (4), 72 (4), 71 (11), 70 (7), 69 (22),
68 (30), 67 (28), 66 (4), 65 (3), 58 (7), 57 (100), 56 (19), 55
41), 54 (32), 53 (8), 51 (3).
4
.4. Semihydrogenation of alkynes
(
In a 30 mL reaction tube, nickel chloride (130 mg, 1 mmol)
was added over a suspension of lithium (28 mg, 4 mmol)
and DTBB (13 mg, 0.05 mmol) or 4-vinylbiphenyl/divinyl-
benzene copolymer (40 mg, 0.2 mmol) in THF (2 mL)
at room temperature under argon. The reaction mixture,
which was initially dark green, changed to black indicating
that nickel(0) was formed. After 10 min, THF (18 mL),
EtOH (0.12 mL, 2 mmol, for internal alkynes) or i-PrOH
4.4.3. (Z)-1-Methoxydec-3-ene (Table 1, entry 10). Yield:
93%; H NMR (300 MHz, CDCl ): d¼0.88 (t, J¼6.9 Hz, 3H,
1
3
CH CH ), 1.23–1.43 [m, 8H, (CH ) CH ], 2.04 (td, J¼6.7,
3
2
2 4
3
6.6 Hz, 2H, CH (CH ) CH ), 2.33 (td, J¼6.8, 6.7 Hz, 2H,
2
2 4
3
CH CH O), 3.34 (s, 3H, CH O), 3.38 (t, J¼7.0 Hz, 2H,
2
2
3
CH O), 5.32–5.40 (m, 1H, CH]CHCH CH O), 5.43–5.52
2
2
2
1
3
(m, 1H, CH]CHCH CH O); C NMR (75 MHz, CDCl3):
2
2
(
0.15 mL, 2 mmol, for terminal alkynes), and the corre-
d¼14.0 (CH CH ), 22.6, 27.3, 27.7, 28.9, 29.5, 31.7
3
2
sponding alkyne (1 mmol) were consecutively added. The
needle of the argon inlet was removed and the septum was
sealed with insulated tape. The progress of the reaction
was monitored by GLC–MS. After total conversion of the
starting material, the resulting suspension was diluted with
Et O (10 mL) and filtered through a pad containing silica
2
gel (lower layer) and Celite (upper layer) (ca. 3:1). The resi-
due obtained was purified by flash column chromatography
[(CH ) , CH CH O], 58.5 (CH O), 72.4 (CH O), 125.3
2 5 2 2 3 2
(CH]CHCH CH O),132.0(CH]CHCH CH O);IR(film):
2
2
2
2
ꢃ1
n¼3008, 724 (HC]C), 1119 cm ; MS (EI): m/z (%)¼170
+
(M , 2), 142 (2), 139 (6), 138 (53), 127 (2), 110 (15), 109
(20), 97 (8), 96 (37), 95 (33), 85 (4), 84 (2), 83 (16), 82
(55), 81 (68), 80 (3), 79 (10), 77 (4), 71 (21), 70 (4), 69
(29), 68 (100), 67 (72), 66 (10), 65 (4), 59 (3), 58 (17), 57
(5), 56 (6), 55 (48), 54 (42), 53 (12), 51 (2); HR-MS: calcd
for C H O: 170.1671; found: 170.1660.
(
silica gel, hexane/EtOAc 9:1 for entries 7, 8, and 10–13 in
1
1 22

100
F. Alonso et al. / Tetrahedron 63 (2007) 93–102
2
9
4
.4.4. (Z)-5-Benzyloxypent-2-ene (Table 1, entry 12).
(9), 210 (63), 196 (4), 138 (2), 126 (5), 124 (2), 112 (20),
110 (5), 98 (3), 97 (7), 96 (4), 86 (27), 84 (3), 83 (9), 82
(3), 81 (3), 79 (2), 74 (6), 73 (47), 72 (16), 71 (3), 70 (2),
69 (11), 68 (3), 67 (7), 59 (3), 58 (100), 57 (5), 56 (8), 55
(16), 54 (3), 53 (2); HR-MS: calcd for C H N: 225.2457;
15 31
found: 225.2500.
1
Yield: 73%; H NMR (300 MHz, CDCl ): d¼1.62 (d,
3
J¼6.5 Hz, 3H, CH ), 2.38 (td, J¼7.0, 6.9 Hz, 2H,
3
CH CH O), 3.47 (t, J¼6.9 Hz, 2H, CH CH O), 4.51 (s,
2
2
2
2
2
H, CH Ph), 5.38–5.46 (m, 1H, CH CH]CH), 5.49–5.59
2
3
1
3
(
m, 1H, CH CH]CH), 7.24–7.33 (m, 5H, 5ꢂArH);
C
3
NMR (75 MHz, CDCl ): d¼12.8 (CH ), 27.6 (CH CH O),
3
3
2
2
6
1
9.8, 72.8 (CH CH O, CH Ph), 125.8, 126.4, 127.4, 127.5,
2
4.4.8. (Z)-N,N-Diethyl-5-phenylpent-2-en-1-amine (Table
1, entry 16). Yield: 94%; H NMR (300 MHz, CDCl ):
2
2
1
28.3, 138.5 (ArC, CH CH]CH, CH CH]CH); IR
3
3
3
(
film): n¼3086, 3064, 735, 697 (HC]C), 1101 (C–
d¼1.00 (t, J¼7.1 Hz, 6H, 2ꢂCH ), 2.35–2.52 (m, 6H,
3
ꢃ1
+
+
O) cm ; MS (EI): m/z (%)¼176 (M , 4), 175 (M ꢃ1, 5),
32 (3), 107 (3), 105 (3), 104 (4), 92 (10), 91 (100), 89
2), 77 (2), 65 (8), 55 (3), 51 (2); HR-MS: calcd for
C H O: 176.1201; found: 176.1231.
2ꢂCH CH , CH Ph), 2.67 (t, J¼7.6 Hz, 2H, CH CH Ph),
2
3
2
2
2
1
(
3.03 [d, J¼5.9 Hz, 2H, CH N(CH CH ) ], 5.45–5.60
2
2
3 2
(m, 2H, CH]CH), 7.18–7.30 (m, 5H, 5ꢂArH);
1
3
C NMR (75 MHz, CDCl ): d¼11.7 (2ꢂCH ), 29.5,
1
2
16
3
3
3
5.8
(CH CH Ph),
2
46.7
(2ꢂNCH CH ),
49.6
2
2
3
3
4
4
.4.5. (Z)-1-Benzyloxyhex-3-ene (Table 1, entry 13).
[CH N(CH CH ) ], 125.8, 127.7, 128.3, 128.4, 131.1
2 2 3 2
1
Yield: 79%; H NMR (300 MHz, CDCl ): d¼0.96 (t,
(6ꢂArC, CH]CH); IR (film): n¼3062, 3025, 698
3
ꢃ1
+
J¼7.5 Hz, 3H, CH ), 2.06 (td, J¼14.8, 7.3 Hz, 2H,
(HC]C) cm ; MS (EI): m/z (%)¼217 (M , 9), 216
3
+
CH CH ), 2.37 (td, J¼7.1, 6.8 Hz, 2H, CH CH O), 3.47
(M ꢃ1, 3), 203 (3), 202 (21), 188 (4), 145 (6), 144 (3), 143
2
3
2
2
(
5
t, J¼7.1 Hz, 2H, CH CH O), 4.51 (s, 2H, CH Ph), 5.32–
(4), 130 (2), 129 (14), 128 (5), 127 (2), 124 (2), 115 (4),
112 (12), 110 (6), 96 (4), 92 (8), 91 (100), 89 (2), 86 (21),
82 (2), 77 (2), 74 (8), 73 (36), 72 (13), 67 (3), 66 (2), 65
(9), 59 (3), 58 (67), 57 (2), 56 (7), 55 (2), 54 (2), 53 (2), 51
2
2
2
.40 (m, 1H, CH CH CH]CH), 5.43–5.51 (m, 1H,
3 2
1
3
CH CH CH]CH), 7.22–7.34 (m, 5H, 5ꢂArH); C NMR
3
2
(
(
75 MHz, CDCl ): d¼14.2 (CH ), 20.6 (CH CH ), 27.8
3
3
2
3
CH CH O), 70.0, 72.8 (CH CH O, CH Ph), 124.8, 127.4,
2 2 2 2 2
(2); HR-MS: calcd for C H N: 217.1830; found: 217.1819.
15 23
1
27.5, 128.3, 133.6, 138.5 (6ꢂArC, CH]CH); IR (film):
ꢃ1
37
n¼3087, 3064, 735, 696 (HC]C), 1102 (C–O) cm
;
4.4.9. 3-Benzyloxypent-1-ene (Table 2, entry 3). Yield:
74%; H NMR (300 MHz, CDCl ): d¼0.90 (t, J¼7.5 Hz,
+
+
1
MS (EI): m/z (%)¼190 (M , 2), 189 (M ꢃ1, 2), 161
3
(
(
(
6), 107 (6), 104 (3), 99 (3), 92 (11), 91 (100), 89 (2), 82
2), 81 (2), 77 (2), 69 (4), 68 (3), 67 (2), 65 (7), 55 (3), 51
2); HR-MS: calcd for C H O: 190.1358; found:
3H, CH ), 1.48–1.60 (m, 1H, CH H CH ), 1.62–1.74 (m,
3
a
b
3
1H, CH H CH ), 3.62 (td, J¼6.9, 6.8 Hz, 1H, CHO), 4.33,
a
b
3
4.57 (AB system, J¼12.0 Hz, 2H, CH O), 5.14–5.21 (m,
1
3
18
2
1
90.1343.
2H, CH ]CH), 5.64–5.76 (m, 1H, CH]CH ), 7.19–7.33
2
2
1
3
(
m, 5H, 5ꢂArH); C NMR (75 MHz, CDCl ): d¼9.6
3
4
1
.4.6. (Z)-N,N-Diethylnon-2-en-1-amine (Table 1, entry
4). Yield: 90%; H NMR (300 MHz, CDCl ): d¼0.88
(CH ), 28.2 (CH CH ), 69.9 (CH O), 81.8 (CHO), 117.0
3 2 3 2
3
5
1
(CH ]CH), 127.2, 127.5, 128.2, 138.7, 138.8 (6ꢂArC,
3
2
(
2
t, J¼6.4 Hz, 3H, CH CH CH ), 1.04 (t, J¼7.2 Hz, 6H,
CH]CH ); IR (film): n¼3065, 3030, 994, 735, 697
3
2
2
2
ꢃ1
+
ꢂCH CH N), 1.09–1.49 [m, 8H, (CH ) CH ], 2.07 [t,
(HC]CH) cm ; MS (EI): m/z (%)¼148 (M ꢃ28, 2), 147
3
2
2 4
3
J¼6.5 Hz, 2H, CH (CH ) CH ], 2.52 (q, J¼7.2 Hz, 4H,
(20), 107 (6), 92 (11), 91 (100), 79 (3), 77 (4), 65 (7), 55
(3), 51 (2); HR-MS: calcd for C H O: 176.1201; found:
176.1206.
2
2 4
3
2
5
ꢂNCH CH ), 3.11 [d, J¼5.8 Hz, 2H, CH N(CH CH ) ],
2
3
2
2
3 2
12 16
1
3
.42–5.56 (m, 2H, CH]CH);
C NMR (75 MHz,
CDCl ): d¼11.8 (2ꢂCH CH N), 14.1 (CH CH CH ),
3
3
2
3
2
2
2
4
2.6, 27.5, 28.9, 29.6, 31.7 [(CH ) ], 46.7 (2ꢂNCH CH ),
4.5. Complete hydrogenation of alkynes
2
5
2
3
9.6 [CH N(CH CH ) ], 126.7 (CH]CHCH N), 132.5
2
2
2
3 2
(
(
(
CH]CHCH N); IR (film): n¼3012, 1655, 756
The reaction was performed according to the procedure
described for the semireduction of alkynes but using the
following amounts of reactants: nickel chloride (130 mg,
1 mmol), lithium (70 mg, 10 mmol), 4-vinylbiphenyl/
divinylbenzene copolymer (40 mg, 0.2 mmol) or DTBB
(13 mg, 0.05 mmol), EtOH (0.29 mL, 5 mmol), and the al-
kyne (1 mmol). The residue obtained was purified by flash
column chromatography (silica gel, hexane or hexane/
EtOAc 9:1 for entries 1, 3, and 6 in Table 3) or neutral alu-
mina (hexane/EtOAc 8:2 for entry 4 in Table 3) to give the
corresponding alkanes. For the carboxylic acids in entries
5 and 7 (Table 3), 2 M HCl (15 mL) was added, the resulting
mixture being extracted with CH Cl (3ꢂ10 mL).
2
ꢃ1
+
HC]C) cm ; MS (EI): m/z (%)¼197 (M , 6), 196
+
M ꢃ1, 3), 183 (3), 182 (21), 126 (3), 112 (17), 110 (3),
9
8 (2), 96 (3), 86 (20), 84 (2), 83 (9), 82 (2), 81 (2), 74
(
5
4), 73 (28), 72 (12), 70 (2), 69 (16), 68 (2), 67 (5), 59 (3),
8 (100), 57 (4), 56 (10), 55 (15), 54 (3), 53 (2); HR-MS:
calcd for C H N: 197.2143; found: 197.2156.
1
3 27
4
1
.4.7. (Z)-N,N-Diethylundec-2-en-1-amine (Table 1, entry
5). Yield: 87%; H NMR (300 MHz, CDCl ): d¼0.88 (t,
3
6
1
3
J¼6.6 Hz, 3H, CH CH CH ), 1.04 (t, J¼7.2 Hz, 6H,
3
2
2
2
2
2
5
ꢂCH CH N), 1.20–1.49 [m, 12H, (CH ) CH ], 2.02–
3
2
2 6
3
.07 [m, 2H, CH (CH ) CH ], 2.52 (q, J¼7.2 Hz, 4H,
2 2 6 3
2
2
ꢂNCH CH ), 3.10 [d, J¼5.8 Hz, 2H, CH N(CH CH ) ],
2
3
2
2
3 2
1
3
.42–5.56 (m, 2H, CH]CH);
C NMR (75 MHz,
n-Heptanoic and n-octanoic acids were characterized
by comparison of their physical and spectroscopic data
with those of commercially available samples (Aldrich).
1,2-Diphenylethane, trimethylphenethylsilane, and 1-ethyl-
cyclohexanol gave satisfactory analyses by comparison of
their physical and spectroscopic data with those of authentic
CDCl ): d¼11.8 (2ꢂCH CH N), 14.1 (CH CH CH ),
3
3
2
3
2
2
2
4
(
2.7, 27.5, 29.3, 29.5, 29.6, 29.6, 31.9 [(CH ) CH ],
2 7 3
6.7 (2ꢂNCH CH ), 49.6 [CH N(CH CH ) ], 126.7
2
3
2
2
3 2
CH]CHCH N), 132.5 (CH]CHCH N); IR (film):
2 2
ꢃ1
n¼3012, 1650, 756 (HC]C) cm
; MS (EI): m/z
%)¼226 (M +1, 2), 225 (M , 16), 224 (M ꢃ1, 9), 211
+
+
+
38
(
samples.

F. Alonso et al. / Tetrahedron 63 (2007) 93–102
101
3
9
4
.5.1. N,N-Diethylnonan-1-amine (Table 3, entry 4).
GRUPOS03/135 and GV05/005). I.O. thanks the Basque
Country Government for a postdoctoral fellowship. We
also thank MEDALCHEMY S.L. for a gift of chemicals.
1
Yield: 98%; H NMR (300 MHz, CDCl ): d¼0.88 (t,
3
J¼6.5 Hz, 3H, CH CH CH ), 1.02 (t, J¼7.2 Hz, 6H,
3
2
2
2
ꢂCH CH N), 1.20–1.40 [m, 14H, (CH ) CH ], 2.40 (t,
3
2
2 7
3
J¼7.7 Hz, 2H, NCH CH ), 2.52 (q, J¼7.1 Hz, 4H,
2 2
1
3
2
(
2
5
(
(
ꢂNCH CH );
C NMR (75 MHz, CDCl ): d¼11.5
References and notes
2
3
3
2ꢂCH CH N), 14.0 (CH CH CH ), 22.6, 26.8, 27.7,
3
2
3
2
2
9.3, 29.5, 29.6, 31.8 [(CH ) CH ], 46.8 (2ꢂNCH CH ),
1. For reviews, see: (a) Siegel, S. Comprehensive Organic
Chemistry; Trost, B. M., Fleming, I., Semmelhack, M. F.,
Eds.; Pergamon: Oxford, 1991; Vol. 8, Chapter 3.1; (b)
Moln ꢀa r, A.; S ꢀa rk ꢀa ny, A.; Varga, M. J. Mol. Catal. A: Chem.
2
7
3
2
ꢃ1
3
2.9 (NCH CH ); IR (film): n¼1380 (C–N) cm ; MS
2
2
+
+
EI): m/z (%)¼199 (M , 4), 198 (M ꢃ1, 1), 184 (5), 87
6), 86 (100), 84 (1), 72 (5), 58 (4), 57 (1), 56 (2), 55 (2).
2
001, 173, 185–221; (c) Nishimura, S. Handbook of
4
.6. Semihydrogenation of dienes
Heterogeneous Catalytic Hydrogenation for Organic
Synthesis; Wiley-Interscience: New York, NY, 2001.
The reaction was performed according to the procedure
described for the semireduction of alkynes but using the
following amounts of reactants: nickel chloride (130 mg,
2. Takaya, H.; Noyori, R. Comprehensive Organic Chemistry;
Trost, B. M., Fleming, I., Semmelhack, M. F., Eds.;
Pergamon: Oxford, 1991; Vol. 8, Chapter 3.2.
1
0
mmol), lithium (31 mg, 4.4 mmol), DTBB (13 mg,
.05 mmol) or 4-vinylbiphenyl/divinylbenzene copolymer
3. For a general reference, see: (a) Pasto, D. J. Comprehensive
Organic Chemistry; Trost, B. M., Fleming, I., Semmelhack,
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352; (c) Brandsma, L.; Nieuwenhuizen, W. F.; Zwikker,
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(
40 mg, 0.2 mmol), EtOH (0.14 mL, 2.4 mmol), and the di-
ene (1 mmol). The residue obtained was purified by flash
column chromatography (silica gel, hexane) to give the cor-
responding alkenes.
Cyclooctene and cycloheptene were characterized by com-
parison of their physical and spectroscopic data with those
of commercially available samples (Aldrich). (R)-(+)-p-
4
0
Menth-1-ene and 3a,4,5,6,7,7a-hexahydro-4,7-methano-
1
3
8
H-indene were characterized by comparison of their
physical and spectroscopic data with those described in the
literature.
4. (a) Lindlar, H. Helv. Chim. Acta 1952, 35, 446–450; (b) Lindlar,
H.; Dubuis, R. Org. Synth. Coll. 1973, 5, 880–883.
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4
.7. Hydrogenation of alkenes
3
987.
The reaction was performed according to the procedure de-
scribed for the semireduction of alkynes but using the fol-
lowing amounts of reactants: nickel chloride anhydrate
6. (a) Gallois, P.; Brunet, J.-J.; Caub ꢁe re, P. J. Org. Chem. 1980, 45,
1946–1950; (b) Brunet, J.-J.; Caub ꢁe re, P. J. Org. Chem. 1984,
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(
130 mg, 1 mmol), lithium [35 mg, 5 mmol (for entries 1,
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2
4
5
, 5, and 8 in Table 5), 70 mg, 10 mmol (for entries 3 and
in Table 5), 29 mg, 4.2 mmol (for entries 6 and 7 in Table
)], and DTBB (13 mg, 0.05 mmol) or 4-vinylbiphenyl/
divinylbenzene copolymer (40 mg, 0.2 mmol), EtOH
0.17 mL, 3 mmol (for entries 1, 2, 5, and 8 in Table 5),
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[
0
2
.28 mL, 5 mmol (for entries 3 and 4 in Table 5), 0.12 mL,
.2 mmol (for entries 6 and 7 in Table 5)], and the alkene
or diene (1 mmol). The residue obtained was purified by
flash column chromatography (silica gel, hexane or hexane/
EtOAc 9:1) to give the corresponding alkane.
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1
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physical and spectroscopic data with those of commercially
available samples (Aldrich). 1,2-Diphenylethane and 1,4-
diphenylbutane gave satisfactory analyses by comparison
of their physical and spectroscopic data with those of authen-
3
8
tic samples.
1
6. (a) Paquette, L. A. Encyclopedia of Reagents for Organic
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S.; Yamashina, T. Bull. Chem. Soc. Jpn. 2004, 77, 1405–1406.
Acknowledgements
This work was generously supported by the Spanish Minis-
terio de Educaci ꢀo n y Ciencia (MEC; grant no. CTQ2004-
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0
1261) and the Generalitat Valenciana (GV; grants nos.

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