A copper (I or II)/diethylphosphite catalytic system for base-free additive dimerization of alkynes

Article abstract of DOI:10.1016/j.tet.2016.11.073

Copper (I) or copper (II) salts and oxides promote regioselective head-to-head additive dimerization of aromatic and aliphatic terminal alkynes in the presence a catalytic amount of diethylphosphite. The reaction proceeds under ambient conditions without

Full text of DOI:10.1016/j.tet.2016.11.073

Accepted Manuscript
A copper (I or II) / diethylphosphite catalytic system for base-free additive dimerization
of alkynes
Inna G. Trostyanskaya, Irina P. Beletskaya
PII:
S0040-4020(16)31253-4
10.1016/j.tet.2016.11.073
TET 28287
DOI:
Reference:
To appear in: Tetrahedron
Received Date: 15 August 2016
Revised Date: 17 November 2016
Accepted Date: 28 November 2016
Please cite this article as: Trostyanskaya IG, Beletskaya IP, A copper (I or II) / diethylphosphite
catalytic system for base-free additive dimerization of alkynes, Tetrahedron (2016), doi: 10.1016/
j.tet.2016.11.073.
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A copper (I or II) / diethylphosphite catalytic system for
base-free additive dimerization of alkynes
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Inna G. Trostyanskaya, Irina P. Beletskaya.*
Department of Chemistry, M. V. Lomonosov Moscow State University,
Leninski gory, 1(3), GSP-1, Moskow 119991,Russia. Fax: (+7)-499-135-
5
3-28; e-mail beletska@org.chem.msu.ru (I.P.Beletskaya).
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A copper (I or II) / diethylphosphite catalytic system for base-free additive
dimerization of alkynes
a
a
Inna G. Trostyanskaya, Irina P. Beletskaya. *
Department of Chemistry, M. V. Lomonosov Moscow State University, Leninski gory, 1(3), GSP-1, Moskow 119991,Russia. Fax: (+7)-499-135-53-28; e-mail
beletska@org.chem.msu.ru (I.P. Beletskaya)
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ABSTRACT
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Accepted
Copper (I) or copper (II) salts and oxides promote regioselective head-to-head additive
dimerization of aromatic and aliphatic terminal alkynes in the presence a catalytic amount of
diethylphosphite. The reaction proceeds under ambient conditions without any added base with
the formation of 1,4-disubstituted 1,3-enynes with the E isomer as major product in good to
excellent yields. A plausible mechanism for additive dimerization of terminal alkynes is
proposed.
Available online
Keywords:
catalysis
2
016 Elsevier Ltd. All rights reserved.
copper salts and oxides
diethylphosphite
alkynes
1
1
,3-enynes
,4-diphenylbuta-1,3-diyne
1
. Introduction
(RO) P(O)H (R=Et, Ph), gives in high yield (up to 90%) the
2
corresponding conjugated enyne, resulting from the additive
dimerization of alkyne, instead of the expected H-P(O) addition
product.
1
In our earlier study of the copper-catalyzed addition of S-H
2
and P(O)-H bonds to alkynes we have serendipitously observed
that the Cu(II) catalyzed reaction of phenylacetylene with
Scheme 1. Dimerization of phenylacetylene.
Corresponding autor. . Fax: (+7)-499-135-53-28; e-mail
beletska@org.chem.msu.ru (I.P. Beletskaya)
1

Table 1. Reaction of phenylacetylene catalyzed by ligand–
ACCEPTED MANUSCRIPT
free copper salts under air.
Since conjugated enynes are very important building blocks
3
for the synthesis of biologically active molecules and materials
A
Yield
4
for molecular electronics, we decided to study this reaction in
more detail. It is known that stereodefined enynes (E or Z) can be
obtained by cross-coupling reactions of alkenyl halides with
terminal alkynes under Cu(I) or Pd catalysis, by the reaction of
vinylsilanes with bromoalkynes, or using a Heck reaction.
Entry
[Cu]-salts
Time
[a,b]
[
h]
[%]
5
6
7
8
1
2
3
4
5
6
Cu(acac)
Cu(acac) /Zn [10 mol%]
Cu(acac) /Ph P [10 mol%]
Cu(acac) /Et N [2 mol]
2
5
2
3
6
4
2
65
40
2
However, the simplest and most atom-economical route to
conjugated enynes is certainly the metal-catalyzed additive
dimerization of alkynes. This reaction was studied for various (early
2
3
90
2
3
<10
<10
70
[F C(O)CH C(O)CH ] Cu
3
2
3
2
9a,b
or late) transition metal catalysts and lanthanides.
the general copper catalyzed version of this transformation is still
unknown, with notable exception of acetylene itself; its
Surprisingly,
[F
3
C(O)CH
2
C(O)CH
3
]
2
Cu/Ph
2
P(O)OH [10
mol%]
C(O)CH Cu/CH
mol%]
Copper prolinate/CH COOH [10 mol%]
Cu(OAc)
CuSO
a
7
[F
3
C(O)CH
2
3
]
2
3
COOH [10
2
50
dimerization on CuCl-based Nieuwland catalyst is used in the
industrial production of vinylacetylene and is mentioned in many
textbooks, while acetylene dimerization with copper acetylenide is
known as the Strauss reaction. The most common problem in the
additive dimerization of unsymmetrical alkynes is the formation of
head-to-head (E and Z) and head-to-tail isomer mixtures.
10
8
9
3
6
4
4
30
75
50
11
2
1
0
4
a
Reaction conditions: phenylacetylene (1 mmol), [Cu}-salts (5 mol%),
DMF/THF=3/1 mL
b
Isolated yield
To avoid this unwanted dimerization all subsequent reactions
were carried out under a dry argon atmosphere.
Table 2. Screening of the efficiency of Cu-precursors and
additives for the dimerization of phenylacetylene.
Scheme 2. Enynes formed by catalytic dimerization of terminal
alkynes.
Dimerization can be also accompanied by the formation of
12
Glaser-type 1,3-diynes (R−≡−≡−R), and, under early transition
metal catalysis, of triene byproducts (R−=·=·=−R). In addition to
all these difficulties, related to regio- and stereoselectivity, there
is a problem of finding a catalyst equally effective for aromatic
and aliphatic acetylenes. In his pioneering work B. Trost
developed the palladium catalyzed conditions, which allowed to
Entry
[Cu]-catalyst
Cu(acac)2
Additive
Time
[h]
Yield
[a,b]
[%]
1
2
3
4
5
6
7
8
9
3
Et N (2 equiv.)
8
n.d.
n.d.
n.d.
<5
Cu(OAc)
2
Et
2
NH (1 equiv.)
8
13
obtain head-to-tail isomers selectively. However, it was soon
shown that changing the palladium catalyst, the type of alkyne,
using a different base and other additives, allows to obtain either
Cu(OAc)
2
CH
3
COOH/H
2
O
15
2
Cu(acac)
CuSO
Cu(acac)
CuSO
Cu(OAc)
2
Zn
4
Sodium ascorbate
8
n.d.
n.d.
<10
<10
<10
14,15
15a,b
head-to-head
or head-to-tail isomers.
For example, head-
2
Ph
Ph
Ph
Ph
Ph
Ph
3
3
3
3
3
3
P
P
P
P
P
P
17
8-20
8
to-head isomer is formed in the reaction of terminal alkyne with
activated internal alkyne in water under joint CuBr-PdCl (PPh )
[c]
[c]
c]
c]
4
2
3 2
16
2
2
catalysis. In this paper we extended our reaction on variety
terminal alkynes using Cu (I) and Cu (II) salts and oxides in the
[
Cu(OTf)
2
8
[
1
1
1
1
1
1
1
1
1
1
0
1
2
3
4
5
6
7
8
9
0
CuO
20
30
8
n.d.
n.d.
n.d.
n.d.
30
presence of catalytic amount of (EtO) P(O)H.
2
2
Cu O
Cu(OTf)
2
3
(EtO) P
Cu(OTf)
2
Bu
3
P
8
2
.Results and discussion
CuSO
4
4
H
3
3
PO
3
2
8
CuSO
H
PO
8
15
Cu(acac)
CuSO
Cu(OTf)
2
(PhO)
2
P(O)H
6
90
Initial optimization of reaction conditions was performed using
phenylacetylene dimerization as a model reaction.
4
(EtO)
(EtO)
(EtO)
(EtO)
2
P(O)H
P(O)H
P(O)H
P(O)H
2
90
2
2
2
2
4
88
17
Under aerobic conditions this reaction in DMF-THF (3:1) gave
,4-diphenylbutadiyne as the only product formed. Depending on
Cu(OAc)
2
4
90
1
2
CuO
7
86
the Cu(II) salt catalyst and additive (Table 1) its yield varied
from low (entries 2, 4, 5, 8) to moderate (entries 1, 6, 7, 9) or
even nearly quantitative (entry 3).
a
Phenylacetylene (1 mmol), copper catalyst (5 mol%), additive (10-20
mol%), DMF/THF=3/1 mL, 70-75 °C, under argon.
b
Inspect of the reaction on the TLC (Silufol, eluent-toluene/hexane=1/3).
c 31
P NMR spectrum always showed signal of [Cu](Ph
3
P)
2
complexes (δ
p
=23-
.
2
5 m.d.)
2

We tested different Cu(II) salts as well as Cu O and CuO oxides
in the presence of different additives, which can serve as ligands or
base (entries 1, 2), acid (entry 3), reducing agents (Zn – entry 4,
sodium ascorbate − entry 5) no enyne product is formed.
2
ACCEPTED MANUSCRIPT
reducing agents (Table 2). In the presence of such additives as amine
a
Table 3. [Cu]-catalyzed additive dimerization of phenylacetylene.
[c]
Entry
[Cu}-catalyst
(EtO)
2
P(O)H
Solvent
Time [h]
Yield
[%]
E/Z ratio [2a]
[
b]
[
mol%]
1
2
3
CuBr
Copper prolinate
C(O)CH C(O)CH
2
10-20
10
10
DMF/THF 3/1
DMF/THF 3/1
DMF/THF 3/1
9
15
16
<10
<5
<5
n.d.
n.d.
n.d.
[CF
3
2
3
]
2
Cu
4
5
6
7
Cu(OAc)
Cu(OAc)
Cu(OAc)
Cu(OAc)
2
2
2
2
10-20
100
10-20
10-20
DMF/THF 3/1
DMF/THF 3/1
DMSO
5
5
5
8
98[
3/1
3/1
3/1
3/1
d]
70
32
25
THF
8
9
CuSO
CuSO
4
10-20
100
10-20
10-20
DMF/THF 3/1
DMF/THF 3/1
DMF/THF 3/1
DMSO
2
2
2
6
92
93
88
50
2.5/1
3/1
2.5/1
2.5/1
4
1
1
0
1
CuSO
4
·5H
2
O
CuSO
4
1
1
2
3
Cu(OTf)
(CuOTf)
2
10-20
10-20
DMF/THF 3/1
DMF/THF 3/1
4
4
87
86
2.5/1
3/1
2
[
e]
1
1
4
5
CuO
CuO
10-20
100
DMF/THF 3/1
DMF/THF 3/1
7
7
86 [
2/1
3/1
e]
98
1
1
6
7
Cu
Cu
2
2
O
O
10-20
100
DMF/THF 3/1
DMF/THF 3/1
7
7
88
95
2.5/1
2.5/1
a
b
c
d
e
o
Reaction condition: diphenylacetylene (1 mmol), catalyst (5 mol%), (EtO)
Isolated yield
E/Z isomer ratio determined by H NMR
8-30% of E-PhCH=CHP(O)(OEt) is formed
Increased reaction time because of poor solubility of copper oxides, and increased amount of diethylphosphite to increase the copper concentration in the
reaction mixture
2
P(O)H (10-100 mol%), 70-75 C, on argon.
1
2
2
The addition of phosphine or triethyl phosphite as ligand was
also ineffective, since only minor amounts of the enyne product
<10%) were observed. Slightly better results were obtained with
inorganic phosphoric and hypophosphorous acids (entries 14 and
5), which are weak ligands but good reducing agents. However,
only the use of diorganophosphites – (PhO) P(O)H (entry 16) and
On finding the optimum reaction conditions we have carried
out the additive dimerization of different aromatic and aliphatic
alkynes (Table 4). Electron donating substituents in the alkyne
make the reaction more difficult, and electron withdrawing
substituents facilitate it (entries 1-3).
(
1
The aliphatic alkynes are therefore less reactive than aromatic
(entries 4-8), while the propiolic acid is the most reactive
substrate (entry 9). There is a clear correlation between the
alkyne reactivity and the E/Z-product ratio: the less reactive
alkylacetylenes produce a higher content of E isomer, while with
propargylic alcohol and propargylamine only E isomer is formed
(entries 7, 8 and 10). With less reactive aliphatic alkynes the
Cu(OTf)2 shows better results than CuSO ·5H O or copper
2
(
EtO) P(O)H (entries 17-20) effectively promoted the additive
2
dimerization with high yield of enyne product.
In the following runs diethylphosphite was used as a cheaper
and easily available reagent (Table 3). It was found that
irrespective of the Cu-source (5 mol%) except copper bromide,
prolinate and trifluoroacetylacetonate (entries 1-3) the reaction in
the presence of (EtO) P(O)H (10-20 mol%) in DMF/THF (entries
2
4
2
4
, 8-10, 12, 13-17) gave the head-to-head 1,3-enyne in high yield
oxides.
In case of propargylamine (entry 9), conversion was 100% for
all types of Cu and Cu precatalysts, but the yield of enyne did
not exceed 25 - 30% according to NMR data, the main reaction
product was a dimer with cumulene bond system.
and of the mostly of E-configuration: E/Z = 2.5/1 - 3/1.
+1
+2
The yield decreases in DMSO or neat THF (entries 6, 7, 11).
In case of copper oxides CuO and Cu O the addition of one
equivalent of phosphite increases their solubility, and so
improves yield of the product as compared with 20 mol%
2
(
EtO) P(O)H (entries 14, 16 and 15, 17). It is also worth noting
2
that the salts and oxides of Cu(I) and Cu(II) in the presence of
EtO) P(O)H showed roughly the same efficiency.
(
2
3

Table 4. Additive Dimerization of aryl- and al
A
ky
C
lak
CEP
s. TED MANUSCRIPT
yn
e
Entry Alkyne
[Cu]-catalyst
Time [h]
Yield [%]
E/Z ratio
CuSO ˖5 H O
7
7
72/2b
75/2b
3/1
4
2
1
Cu(OTf)2
2.5/1
1
1
b
c
CuSO ˖H O
1.5
1.5
98/2c
98/2c
3/1
4
2
2
Cu(OTf)2
2.5/1
CuSO ˖H O
2.5
2.5
78/2d
98/2d
2.5/1
2.5/1
4
2
3
4
Cu(OTf)2
1
1
d
e
CuSO4
10
10
9
70/2e
72/2e
86/2e
58/2e
60/2e
88/2e
90/2e
98/2e
73/2e
86/2e
5/1
5/1
8/1
8/1
8/1
8/1
8/1
10/1
5/1
5/1
CuSO [equiv. (EtO) P(O)H]
4
2
CuSO ˖5 H O
4
2
Cu(OAc)2
Cu(OAc) [equiv.(EtO) P(O)H] 11
CuO
11
2
2
9
9
9
10
8
CuO [equiv. (EtO) P(O)H]
2
Cu O
2
Cu(OTf)2
(CuOTf)2
Cu(OTf)2
11
8
85/2f
86/2f
7/1
5
6
(
CuOTf)2
CuOTf)2
10/1
1
1
f
(
6
5
98/2g
95/2g
2.5/1
2.5/1
CuO
g
CuSO4
5
5
5
90/2h
70/2h
80/2h
8/1
8/1
100% E
7
8
CuSO
CuO
4
˖5 H
2
O
1
1
h
i
CuSO ˖5 H O
7
7
98/2i
98/2i
100% E
100% E
4
2
CuO
CuSO4
2 (20 °C)
70/1j
2/1
9
Cu(OTf)2
1 (20 °C)
1.5 min (70 °C)
75/1j
95/1j
2/1
2/1
1
1
j
(CuOTf)2
CuSO , Cu(OTf) (CuOTf)2,
4
2,
a
1
0
CuO, Cu O
4-15
25-30/2k
100% E
2
k
a
+1
+2
Conversion was 100% for all types of Cu and Cu precatalysts, but the yield of enyne did not exceed 25-30%, according to NMR
data, the main reaction product was a dimer with cumulene bond system.
5

4
.2 General Procedure for the Additive Dimerization of
ACCEPTED MANUSCRIPT
terminal Alkynes
To a mixture of 1 mmol alkyne, 5 mol% of copper compound
in 2.0 mL of solvents (DMF/THF=3/1) 10 or 20 mol% of
EtO) P(O)H was added. After vigorous mixing the reaction was
(
2
stirred at 70-75 °C 1.5-11 h (Tables 3, 4). The record of the
reaction was monitored by TLC. Then the mixture was cooled to
room temperature and concentrated under vacuum. The residue
was diluted with CHCl (10 mL) and hexane (10-15 mL), filtered,
3
and evaporated under vacuum. If the conversion of the reaction
was 95-98% volatile compounds were removed by keeping the
residue under vacuum 10 mm Hg at 70-75°C for 1 h. If needed
the crude products were purified by column chromatography on
silica gel (hexane or hexane/EtOAc 3/1). Yields of 1,4-diphenyl-
1
1
-ene-3-yne (2a) are given in Table 3, 1,4-diaryl- and 1,4-dialkyl-
-ene-3-yne in Table 4.
Scheme 3. The proposed mechanism.
All compounds synthesized in our work, are previously
described. Enynes obtained as a mixture of E and Z isomers were
20-29
1
13
reported in the papers.
The H and C NMR data for the E
It is at present difficult to elucidate the exact role of
dialkylphosphite in this reaction. Being a reducing agent it can
transform Cu(II) to Cu(I), and indeed we have observed (under
heating) the formation of Cu-mirror. Early it was shown that
and Z isomers of the enynes (2) are given in the following
14a-c,15a,30-32
14a,26,27,33-38
26,27,33,37
14a-c,15a,30,31
references: 2a (E),
14a,15a2a (Z),
; 2b (E)1,4a,15a,32
26,27,33-38
2
b (Z),
; 2c (E),
2c (Z),
; 2d (E), 2d
38
23,29,39
23,33,35,36
14c,22,28,30,32,40
(
(
(
Z), ; 2e (E),
; 2e (Z),
; 2f (E),
; 2f
41
18
(
EtO) P(O)H reduces Сu(OAc) to CuOAc in THF for 4 h.
25,32,34
22,28
22,28
30, 40
2
2
Z),
; 2g (E),
;282g (Z),
; 2h (E),
; 2h (Z), ; 2i
A plausible mechanism for the present Cu(I) or Cu(II)-
catalyzed additive dimerization of aryl- or alkylalkynes is
proposed in Scheme 3. But, as can be seen from the data in Table
14b
34
E), ; 2i (Z), ; 2j (E).
The E/Z ratio of the synthesized enynes (2) was determined by
1
2
, other reducing agents are incapable of promoting the reaction.
integration of specific olefin protons in H NMR, as well as the
intensity of the signals of olefin and acetylene hydrocarbons in
Maybe the acidic properties of (EtO) P(O)H are also important
2
13
for the catalytic cycle.
C NMR and comparing the results with the literature data.
The mechanism includes reduction of Cu(II) with
18
(
RO) P(O)H, activation of triple bond, formation of copper
2
acetylenide, insertion of alkyne into carbon-copper bond and
protonolysis. It is clear that we need (not less than 10-20 mol%)
4.3. Characterization data of products
(
RO) P(O)H as donor of electron and proton but possibly also as
2
1
13
a ligand under base - free conditions. Moreover addition of 1 eq.
amine stoped reaction completely.
investigations and applications of this new methodology are
currently underway.
The copies of H and C NMR charts and analytical data are
reported in Supplementary data.
19
Further mechanistic
4
.3.1. 1,4-Diphenylbuta-1-ene-3-yne (2a), (E/Z ratio 2,5-
.0/1). Yields are given in Table 3 (entries 6-11). White solid,
m.p. 93-94 °C. H NMR (400 MHz, CDCl ) δ: 7.92 (d, J=8.0
3
1
3
Hz), 7.49-7,43 (m), 7.42-7.38 (m), 7.36-7.27 (m) (8H, Ph), 7.04
3
. Conclusion
(
d, J=16.2 Hz, E isomer), 6.68 (d, J=11.9, Z isomer), 6.38 (d,
13
J=16.0 Hz, E), 5.91 (d, J=11.9 Hz, Z). NMR C (100.6 MHz,
CDCl ) δ: 141.2 (E), 138.6 (Z), 136.5, 136.3, 131.5, 131.4, 128.7,
3
We have elaborated a simple and efficient method of
1
9
28.6, 128.5, 128.4, 128.3, 126.2, 123.4, 108.1 (E), 107.4 (Z),
6.0 (Z), 91.7 (E), 88.9 (E), 88.2 (Z).
regioselective Cu-catalyzed head-to-head additive dimerization
of aromatic and aliphatic alkynes utilizing various sources of
copper and, as an essential additive, a catalytic amount of
dialkylphosphite. The methogology is general for a variety of
terminal alkynes possessing various functional groups such as
aryl, alkyl, hydroxy and amino groups.
4
.3.2. 1,4-Di(4-methylphenyl)buta-1-ene-3-yne (2b), (E/Z ratio
2
.5/1). Yields for Cu(OTf) 87 mg (75%) (entry 1, Table 4) after
2
column chromatography, eluent hexane, white solid, m.p. 60-62
1
°
C. H NMR (400 MHz, CDCl ) δ: 7.83 (d, J=8.0 Hz), 7.39,
3
7
.37, 7.35, 7.33, 7.30, 7.25, 7.20, 7.18, 7.15, 7.14, 7.12 (Ph), 6.99
4
. Experimental section
.1 General
All reactions were performed under argon atmosphere.
(d, J=16.0 Hz E isomer), 6.64 (d, J=11.9 Hz, Z isomer), 6.33 (d,
J=15.9 Hz, E isomer), 5.85 (d, J=11.9 Hz, Z isomer), 2.36 (s, Z),
13
4
2
1
1
8
.35 (s, E). NMR C (100.6 MHz, CDCl ) δ: 140.8 (E), 138. (Z),
3
34.0, 133.7, 131.4, 129.4, 129.2, 129.1, 129.0, 128.7, 126.2,
21.9, 120.4, 107.2 (E), 106.4 (Z), 95.9 (Z), 92.8 (E), 88.4 (E),
7.5 (Z), 21.5, 21.3.
Solvents were dried and purified before use by standard
procedure, diethylphosphite, copper compounds and all alkynes
were purchased from commercial sources. H and C NMR
spectra were recorded with TMS (0.00 ppm) or CDCl ( H NMR
at 7.26 ppm and C NMR at 77.0 ppm) as internal standards,
1
13
1
3
13
4
.3.3. 1,4-Di(4-trifluoromethylphenyl)buta-1-en-3-yne (2c),
31
(
E/Z ratio 2.5-3.0/1). Yield 167 mg (98%) (entry 2, Table 4),
8
5% H PO was used as the external reference of P NMR
3 4
1
white solid, m.p. 133-135 °C (decomposition). H NMR (400
spectra.
MHz, CDCl ) δ: 7.98 (d, J=7.9 Hz), 7.66, 7.63, 7.62, 7.61, 7.59,
3
5

7
.58, 7.56, 7.54, 7.52 (Ph), 7.10 (d, J=16.4 Hz, E isomer), 6.79
4.3.9. 2,7-Dihydroxy-2,7-dimethyloct-3-en-5-yne (2i) (100% E
isomer). Yield for CuSO ·5H O or CuO 82 mg (98%), (entry 8,
Table 4) white solid, m.p. 99-100 °C. H NMR (400 MHz,
ACCEPTED MANUSCRIPT
(d, J=11.8 Hz, Z isomer), 6.46 (d, J=16.3 Hz, E), 6.06 (d, J=11.9
4
2
13
1
Hz, Z). NMR C (100.6 MHz, CDCl ) δ: 140.7, 139.5. 139.4,
3
1
1
1
38.2, 132.8, 131.8, 130.5 (q, J= 32.0 Hz), 130.1 (q, J= 32.3 Hz),
28.9, 126.9 (q, J=268.0 Hz), 126.6 (q, J=270.2 Hz), 126.5,
25.8, 125.4, 125.3, 110.2 (E), 109.4 (Z), 94.6 (Z), 91.5 (E), 90.5
CDCl ) δ: 6.24 (d, J=16.0 Hz, 1H), 5.74 (d, J=16.0 Hz, 1H), 2.08
(bs,, 2H), 1.54 (s, 6H), 1.33 (s, 6H). NMR C (100.6 MHz,
3
13
CDCl ) δ: 150.5, 106.3, 94.4, 80.1, 70.9, 65.5, 31.4, 29.4.
3
(E), 89.1 (Z).
4
.3.4. 1,4-Di-(4-cyanophenyl)buta-1-en-3-yne (2d), (E/Z ratio
2
.5/1). Yield for Cu(OTf) 124 mg (98%) (entry 3, Table 4),
2
1
4.3.10. But-1-en-3-yne-1,4-dicarboxylicacid, diethylester (2j),
white solid, m.p. 140-142 °C. H NMR (400 MHz, CDCl ) δ:
7
7
Hz, Z isomer), 6.49 (d, J=16.3 Hz, E isomer), 6.11 (d, J=12.0 Hz,
Z isomer). NMR C (100.6 MHz, CDCl ) δ: 140.6 (E), 140.0
3
(
4
E/Z ratio 2/1). Yield for (CuOTf) 93 mg (95%) (entry 9, Table
2
1
.95 (d, J=8.4 Hz), 7.69, 7.67, 7.66, 7.64, 7.62, 7.59, 7.55, 7.53,
.51, 7.49 (Ph), 7.08 (d, J=16.1 Hz, E isomer), 6.81 (d, J=12.0
), red liquid. H NMR (400 MHz, CDCl ) δ: 6.74 (d, J=16.1 Hz,
3
E-isomer), 6.42 (d, J=16.1 Hz, E isomer), 6.29 (d, J=11,6 Hz, Z
isomer), 6.16 (d, J=11.6 Hz, Z isomer), 4.34, 4.24, 4.22, 4.08 (qq,
J=7.0 Hz, 8H), 1.32, 1.29, 1.27, 1.27 (qt, J=7.0 Hz, 12H). NMR
13
3
(
1
(
Z), 138.1, 132.6, 132.0, 129.1, 128.1, 127.7, 126.8, 119.2, 118.5,
18.3, 112.1, 111.8, 111.1 (E), 110.3 (Z), 95.4 (Z), 92.2 (E), 92.0
E), 91.1 (Z).
13
C (100.6 MHz, CDCl ) δ: 170.0 (E), 167.1 (E), 164.6 (Z), 153.0
3
(
8
Z), 135.3 (E), 133.6 (Z) 121.4 (E), 119.3 (Z), 89.4 (Z), 87.0 (E),
1.4 (E), 79.8 (Z), 62.4, 61.5, 61.2 (2H), 14.0.
4
.3.10.
1,4-Diphenylbuta-1,3-diyne
(A).
Yield
for
4
.3.5. Hexadec-7-en-9-yne (2e), (E/Z ratio 5.0-10.0/1). Yield
1
Cu(acac) /Ph P (10 mol%) 182 mg (90%) (entry 3, Table 1)
white solid, m.p. 84-85°C. H NMR (400 MHz, CDCl ) δ: 7.53-
.49 (m, 5H), 7.37-7.31 (m, 5H). NMR C (100.6 MHz, CDCl )
δ: 132.5, 129.2, 128.4, 121.8, 81.5, 73.9.
2
3
for Cu O 108 mg (98%), (entry 4, Table 4) colorless liquid. H
NMR (400 MHz, CDCl ) δ: 6.00 (dt, J=16.0 Hz, J=7.5 Hz, E
isomer), 5.77 (dt, J=8.0 Hz, J=7.5 Hz, Z isomer), 5.41 (m, E+Z
isomer), 2.27 (m), 2.04 (m), 1.48 (m), 1.37 (m), 1.29 (m), 0.88
m). NMR C (100.6 MHz, CDCl ) δ: 143.3 (E), 142.6 (Z),
2
1
3
3
13
7
3
13
(
3
1
3
09.8 (E), 109.3 (Z), 89.5 (Z), 88.7 (E), 82.5 (Z), 79.2 (E), 33.0,
1.8, 31.4, 30.0, 28.8, 28.6, 22.6, 19.4, 19.4, 14.1.
Acknowledgments
The authors thank Dr. P.K. Sazonov (M.V. Lomonosov MSU)
for help in preparing the manuscript.
4
.3.6. Dodec-5-en-7-yne (2f), (E/Z ratio 10/1). Yield 71 mg
1
(
86.0%), (entry 5, Table 4), eluent hexane, colorless liquid. H
NMR (400 MHz, CDCl ) δ: 5.97 (dt, J=!6.0 Hz, J=7.0 Hz, E
3
isomer), 5.74 (dt, J= 8.0 Hz, J=7.4 Hz, Z isomer) (1H), 5.45 [(dt,
J=16.0 Hz, J=3.0 Hz E isomer), + 1/10 Z isomer (1H)], 2.35-1.98
Supplementary Material
13
(m, 4H), 1,70-1.24 (m, 8H), 0.91 (t, 6H). NMR C (100.6 MHz,
CDCl ) δ: 143.3 (E), 142.6 (Z), 109.8 (E), 109.5 (Z), 88.6 (E),
3
1
13
8
2
1
7.2 (Z), 79.8 (Z). 79.2 (E), 32.6 (E), 31.9 (Z), 30.9 (E), 30.4 (Z),
9.7 (E), 29.4 (Z), 22.2 (Z), 22.1 (E), 22.0 (E), 21.9 (Z), 19.0 (E),
8.9 (Z), 14.1 (Z), 13.8 (E), 13,6 (E), 13.4 (Z).
Supplementary data (the copies of H and C NMR charts and
analytical data of all products) associated with this article can be
found in the online version, at
5
. References and notes
4
.3.7. 1,4-Dibenzylbuta-1-en-3-yne (2g), (E/Z ratio 2.5/1.0).
Yield for (CuOTf) 114 mg, (98%) (entry 6, Table 4) yellow
2
1
1. Trostyanskaya, I. G.; Beletskaya, I. P. Synlett. 2012, 23, 535-540.
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liquid. H NMR (400 MHz, CDCl ) δ: 7.21-7.18 (m, 6H), 7.16-
3
7
.04 (m, 4H) (Ph), 6.15 (dt, J=16.6 Hz, J=7.0 Hz, E isomer), 5.92
2
556-2562.
(dt, J=10.1 Hz, J=7.4 Hz, Z isomer), 5.52 (dt, J=10.6 Hz, J=7.0
Hz, Z isomer), 5.44 (dt, J=14.0 Hz, J=7.0 Hz, E isomer), 3.68 (s,
Z isomer), 3.59 (s, E isomer), 3,57 (d, J=2.6 Hz, Z isomer), 3. 31
3
4
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(
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