Rh- and Ru-complex-catalyzed dimerization of arylethynes Rylethynes in aqueous environment

Article abstract of DOI:10.1135/cccc2008172

Complexes [RhCl(PPh₃)₃] and [Ru(CHPh)Cl ₂(PCy₃)2] efficiently catalyzed the dimerization of arylethynes to the corresponding 1,4-substituted enynes in aqueous environment in the presence of sodium dodecyl sulfate. The Rh catalyst exhibited almost exclusive preference for the formation of ￡-isomers, the Ru one exhibits strong preference for the formation of Z-isomers.

Full text of DOI:10.1135/cccc2008172

Rh- and Ru-Complex-Catalyzed Dimerization of Arylethynes
433
Rh - AND Ru -COMPLEX-CATALYZED DIMERIZATION OF
ARYLETHYNES IN AQUEOUS ENVIRONMENT
a1
a2,b,
Petr NOVÁK and Martin KOTORA
*
a
Department of Organic and Nuclear Chemistry, Faculty of Science, Charles University,
Hlavova 8, 128 43 Prague 2, Czech Republic; e-mail: _petrnovak@seznam.cz,
1
2
kotora@natur.cuni.cz
b Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i.,
Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
Received August 14, 2008
Accepted Jan uary 7, 2009
Publish ed on lin e February 28, 2009
Com plexes [Rh Cl(PPh 3)3] an d [Ru(CHPh )Cl2(PCy3)2] efficien tly catalyzed th e dim erization of
aryleth yn es to th e correspon din g 1,4-substituted en yn es in aqueous en viron m en t in th e
presen ce of sodium dodecyl sulfate. Th e Rh catalyst exh ibited alm ost exclusive preferen ce
for th e form ation of E-isom ers, th e Ru on e exh ibits stron g preferen ce for th e form ation of
Z-isom ers.
Keyw ord s: Dim erization s; Rh odium ; Ruth en ium ; W ater ch em istry; Term in al alkin es;
En yn es; Arylacetylen es.
In th e last two decades, developm en t of organ ic reaction s in an aqueous en -
viron m en t h as becom e a h igh ly attractive area. Special in terest is devoted
to th e reaction s catalyzed with tran sition m etal com plexes because of th eir
resem blan ce to en zym atic processes1. It h as been recen tly sh own th at al-
kyn es can un dergo a wide array of tran sform ation s in water or aqueous en -
viron m en t2. In terestin gly, th e area of alkyn e dim erization 3 to 1,3-en yn es in
water h as been som ewh at n eglected. Th is is rath er surprisin g because th is
class of com poun ds can be used as buildin g blocks in th e syn th esis of n a-
tural com poun ds4, biologically active substan ces5, or in term ediates used
in m aterial ch em istry6. Th e on ly exception s are th e recen tly reported Z-se-
lective dim erization of alkyn es in th e presen ce of Ru catalyst with a tripodal
ph osph in e ligan d7 an d E-selective process catalyzed with a Rh com plex
con tain in g sulfon ated ph osph in e ligan ds8. Gen erally, th e dim erization of a
term in al alkyn e RC≡CH m ay result in th e form ation of several isom eric h y-
drocarbon s but th e m ain products are usually (E)- an d (Z)-RCH=CHC≡CR.
Th e dim erization can be catalyzed with a n um ber of tran sition m etal com -
Collect. Czech. Chem. Commun. 2009, Vol. 74, No. 3, pp. 433–442
© 2009 Institute of Organic Chemistry and Biochemistry
doi:10.1135/cccc2008172

434
Novák, Kotora:
plexes of Ru (refs7,9), Rh (refs8,10), Ir (ref.11), Pd (ref.12), Ni (ref.13), Ti (ref.14),
an d lan th an ide15 com poun ds. Th e selectivity in th e form ation of (E)- or
(Z)-en yn es depen ds on a n um ber of factors such as th e reaction m ech a-
n ism , structural features of th e reactin g alkyn es, an d th e catalyst. Th e m ost
frequen tly used Rh -com plex-catalyzed dim erization usually proceeds with
h igh or exclusive E-selectivity (form ally a cis-addition to th e triple bon d).
On th e oth er h an d, in case of th e Ru-com plex-catalyzed reaction s, th e
ligan d en viron m en t aroun d th e cen tral Ru atom plays a sign ifican t role in
con trollin g th e E/Z ratio in th e products9. Th e preferen tial selectivity h as
been explain ed eith er in term s of th e ligan d steric effect (a Ru com plex
with bulky PCy3 sh owed h igh Z-selectivity, wh ereas th e an alogous com plex
with th e less sterically dem an din g PMe3 ligan d exh ibited E-selectivity)9c or
by th e existen ce of differen t reactive species9g.
RESULTS AND DISCUSSION
Sin ce th ere is lack of in form ation on th e scope an d stereoselectivity of
alkyn e dim erization in an aqueous en viron m en t, we decided to explore th e
possibility of carryin g out th e dim erization of alkyn es to (E)- or (Z)-en yn es
in water, catalyzed with com m ercially available Rh an d Ru com plexes
([Rh Cl(PPh 3)3] – Wilkin son catalyst an d [Ru(CHPh )Cl2(PCy3)2] – 1st gen era-
tion Grubbs catalyst) in th e presen ce of surfactan t sodium dodecyl sulfate
(SDS). Th e surfactan t h as been used previously to accelerate a n um ber of
various reaction s in water or aqueous en viron m en t16,17. Th e reaction s were
carried out un der two differen t reaction con dition s: A (catalysts (5 m ole %),
water an d SDS); B catalysts (5 m ole %), water, toluen e 10% v/v, SDS)
SCHEME 1
(Sch em e 1).
In itially, th e dim erization of alkyn es was tested with th e Wilkin son
catalyst, [Rh Cl(PPh 3)3], un der both con dition s. Th e reaction proceeded
with reason able yields (19–86%) on ly un der con dition s B, with excellen t
E-selectivity (Table I). In m ost cases, th e dim erization proceeded with good
yields of th e para-isom ers 1b –1g (en tries 2–7), meta-isom ers of 1h –1j
Collect. Czech. Chem. Commun. 2009, Vol. 74, No. 3, pp. 433–442

Rh- and Ru-Complex-Catalyzed Dimerization of Arylethynes
435
(en tries 8–10), an d ortho-isom ers 1k –1n (en tries 11–14) of substituted
aryleth yn es. As to oth er alkyn es, successful dim erization was perform ed
with ferrocen yleth yn e 1o (en try 15). It is worth m en tion in g th at E-
selectivity was better th an in th e case of previously reported results, e.g.
[Rh Cl(CO)(PPh 3)2]/K2CO3/MeI/THF 10b. In terestin gly, eth yn es such as
3-eth yn ylph en ol, 3-eth yn ylpyridin e, 6-eth yn ylpurin e, prop-2-yn -1-yl
ben zoate, 3-ph en ylpropyn e, an d {2-deoxy-3,5-bis[O-(p-toluoyl)]-α-D-ribo-
furan osyl}eth yn e10c did n ot react. In th e case of 3-eth yn ylpyridin e an d
6-eth yn ylpurin e, coordin ation of th e cen tral Rh atom to lon e electron pairs
of h eteroatom s saturatin g its coordin ation sites m ay accoun t for th e lack of
reactivity. On th e oth er h an d, th e lack of reactivity of alkylalkyn es rem ain s
a puzzle, because th eir facile dim erization in aprotic solven ts was reported
previously10b,10c. Th e obtain ed data are also in agreem en t with th e gen er-
ally accepted th ree-step reaction m ech an ism : (i) oxidative addition of th e
alkyn yl C–H bon d on to th e cen tral rh odium atom givin g a rh odium h y-
TABLE I
[Rh Cl(PPh 3)3]-catalyzed dim erization of alkyn es 1 to en yn es 2
En try
Alkyn e
R
E-2/Z-2
Yield, %a
1
2
1a
1b
1c
1d
1e
1f
H
>99:1
>99:1
>99:1
>99:1
>99:1
>99:1
>99:1
>99:1
>99:1
>99:1
>99:1
>99:1
>99:1
>99:1
>99:1
78
19b
4-Me2N
4-MeO
4-Me
4-Cl
3
18
4
86
5
59
6
4-CF3
4-CN
3-Me
3-Cl
62
22c
7
1g
1h
1i
8
83
9
56
10
11
12
13
14
15
1j
3-CF3
2-MeO
2-Me
2-Cl
25
1k
1l
48
69
57d
1m
1n
1o
2-CF3
FcC≡CH
44
29e
a
b
c
d
Con dition s B. Isolated yields. 9% of th e startin g 1b. 26% of th e startin g 1g. 40% of
e
th e startin g 1m . 14% of th e startin g 1o.
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Novák, Kotora:
dride, (ii) h ydrorh odation of th e secon d alkyn e, an d (iii) reductive elim in a-
tion of a vin yl-alkyn yl-rh odium in term ediate8,10
.
Our atten tion was th en sh ifted to catalysis with [Ru(CHPh )Cl2(PCy3)2].
From th e gen eral poin t of view, it sh ould be m en tion ed th at its use resulted
in th e preferen tial form ation of (Z)-en yn es (Table II). Th e dim erization of
ph en yleth yn e 1a proceeded un der both con dition s A an d B un even tfully to
give a m ixture of (E)- an d (Z)-en yn es 2a in th e 1:5 ratio. In terestin gly,
ph en yleth yn es bearin g electron -don atin g groups 1b (4-Me2N), 1c (4-MeO),
an d 1k (2-MeO), did n ot un dergo dim erization (en tries 3–6, 21 an d 22).
Sim ilarly, (4-cyan oph en yl)eth yn e 1g did n ot react (en tries 13 an d 14), ei-
th er. In all oth er cases, th e alkyn es afforded th e correspon din g en yn es usu-
ally as m ixtures of (E)- an d (Z)-isom ers in various ratios. As to th e differen ce
in th e reaction con dition s, th e dim erization run n in g un der con dition s B
gave h igh er yields an d better Z-selectivity. Th is differen ce is n icely dem on -
strated in th e dim erization of 1f, 1h , 1j, an d 1l. Th us, en yn es 2f were ob-
tain ed in th e yields of 75% (E/Z 1:10) an d 89% (E/Z 1:19) (en tries 11 an d
12), en yn es 2h in th e yields of 51% (E/Z 1:5) an d 83% (E/Z 1:7) (en tries 15
an d 16), en yn es 2j in th e yields of 38% (E/Z 1:10) an d 58% (E/Z 1:17) (en -
tries 19 an d 20), an d en yn es 2l in th e yields of 40% (E/Z 1:2) an d 71% (E/Z
1:4) (en tries 23 an d 24). On ly th e dim erization of 1n un der con dition s A
gave rise to h igh er yields of en yn es 2n an d better selectivity ratio (en tries
27 an d 28). In th is respect, h igh er yields of th e products were obtain ed un -
der con dition A also for 1d (en tries 7 an d 8), 1i (en tries 17 an d 18), an d 1m
(en tries 25 an d 26), but with lower E/Z selectivity th an un der con dition s B.
Un der con dition s A, [4-(dim eth ylam in o)ph en yl]eth yn e 2b an d (4-m eth oxy-
ph en yl)eth yn e 2c un derwen t h ydration of th e triple bon d affordin g th e
correspon din g acetoph en on es; un der con dition s B, th ey did n ot react. In
addition to th e above m en tion ed un successful dim erization s, eth yn es such
as 3-eth yn ylph en ol, 3-eth yn ylpyridin e, 6-eth yn ylpurin e, prop-2-yn -1-yl
ben zoate, 3-ph en ylpropyn e, an d {2-deoxy-3,5-bis[O-(p-toluoyl)]-α-D-ribo-
furan osyl}eth yn e10c did n ot react un der an y con dition s used (probably for
th e sam e reason s as in th e Rh -catalyzed case), eith er. Th e positive effect of
th e presen ce of toluen e was especially sign ifican t wh en solid alkyn es were
dim erized; th e reaction of ferrocen yleth yn e 1o did n ot proceed un der con -
dition s A. Sin ce better results for th e dim erization were obtain ed un der
con dition s B (in a m ixture of water an d toluen e), it is reason able to assum e
th at th e presen ce of toluen e h ad a positive effect on th e solubilization of
th e catalysts an d reactan ts prior to th e form ation of m icelles with SDS.
Th e course of th e reaction is m ore com plex sin ce th e preferen tial form a-
tion of Z- or E-isom ers was observed. Alth ough all proposed reaction m ech -
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Rh- and Ru-Complex-Catalyzed Dimerization of Arylethynes
437
TABLE II
[Ru(CHPh )Cl2(PCy3)2]-catalyzed dim erization of alkyn es 1 to en yn es 2
En try
Alkyn e
R
H
Con dition s
E-2/Z-2
Yield, %a
1
2
1a
A
B
A
B
A
B
A
B
A
B
A
B
A
B
A
B
A
B
A
B
A
B
A
B
A
B
A
B
B
1:5
1:5
96
98
b
3
1b
1c
1d
1e
1f
4-Me2N
4-MeO
4-Me
–
4
n .r.c
b
5
–
6
n .r.c
7
1:10
1:20
1:19
1:10
1:13
1:19
95
8
34
9
4-Cl
46
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
90
4-CF3
4-CN
3-Me
75
89
1g
1h
1i
n .r.c
n .r.c
51
1:5
1:7
83
3-Cl
1:5
94
1:8
90
1j
3-CF3
2-MeO
2-Me
1:10
1:17
38
58
1k
1l
n .r.c
n .r.c
40
1:2
1:4
1:4
1:5
1:10
1:3
1:1
71
1m
1n
2-Cl
68
18
2-CF3
FcC≡CH
66
28
30d
1o
a
b
c
d
Isolated yields. Hydration of alkyn e. No reaction . 30% of th e startin g 1o.
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Novák, Kotora:
an ism s presum e th e form ation of alkyliden e ruth en ium species as on e th e
probable in term ediates, th ey differ in th e origin of E/Z selectivity. Th e pref-
eren tial form ation of Z-isom ers was reported for th e dim erization carried
out with Ru-carben e9g an d oth er Ru com plexes7,9a–9c; on th e oth er h an d,
E-selectivity was reported as well9c,9d,9h . In addition , th e ch an ge from E- to
Z-selectivity was attributed eith er to th e bulkin ess of ph osph in e ligan ds9c or
th e presen ce of protic additives9e. In view of th e foregoin g, it is at th is poin t
difficult to speculate on th e effect of water on preferen tial Z-selectivity.
CONCLUSIONS
We h ave sh own th at stable an d com m ercially available rh odium an d ruth e-
n ium com plexes such as [Rh Cl(PPh 3)3] an d [Ru(CHPh )Cl2(PCy3)2] were able
to efficien tly dim erize aryleth yn es to th e correspon din g en yn es in an aque-
ous en viron m en t. Un der th ese con dition s, th e Rh catalyst h ad h igh er selec-
tivity in th e form ation of (E)-en yn es th an th at reported for th e reaction
carried out in aprotic solven ts. In addition , so far th e largest set of ph en yl-
alkyn es was con verted selectively to th e correspon din g E-en yn es. Th e catal-
ysis with th e Ru com plex was m ore com plicated, but it exh ibited prefer-
en tial selectivity for th e (Z)-en yn es in m ost cases. Th e scope of th e reaction
with respect to substituen ts on th e ben zen e rin g was som ewh at restricted:
ph en ylalkyn es bearin g electron -don atin g groups (e.g. Me2N or MeO) or
stron gly coordin atin g ligan ds (e.g. CN) eith er did n ot react or th e h ydration
of th e triple bon d was observed. Furth er study focusin g on th e use of oth er
am ph iph iles (e.g. th e recen tly reported polyoxyeth an yl α-tocoph eryl seba-
cate (PTS)18) with elucidation of th e roles of water on th e reaction course is
un der way an d will be reported in due course.
EXPERIMENTAL
All solven ts were used as obtain ed. [Rh Cl(PPh 3)3] was prepared by th e previously reported
procedure19. [Ru(CHPh )Cl2(PCy3)2] an d alkyn es were purch ased from Sigm a–Aldrich . NMR
spectra (δ, ppm ; J, Hz) were recorded in CDCl3 solution s on a Varian Un ity 300 In ova in stru-
m en t at 300 MHz (1H) an d 75.6 MHz (13C) an d are referen ced to th e Me4Si sign al. IR spectra
(cm –1) were recorded on a Bruker IFS 88 in strum en t usin g ATR tech n ics. Mass spectra were
recorded on a Fin n igan Mat In cos 50 spectrom eter. HR MS were recorded on a ZAB-SEQ VG
An alytical spectrom eter.
[Rh Cl(PPh 3)3]-Catalyzed Dim erization . Gen eral Procedure
[Rh Cl(PPh 3)3] (0.025 m m ol, 23 m g), alkyn e (0.5 m m ol), toluen e (0.4 m l) an d water (3.6 m l)
were placed in to a vial flask. SDS (1 m m ol, 288 m g) was th en added, an d th e solution was
Collect. Czech. Chem. Commun. 2009, Vol. 74, No. 3, pp. 433–442

Rh- and Ru-Complex-Catalyzed Dimerization of Arylethynes
439
stirred at 50 °C for 15 h . Th e reaction m ixture was th en extracted with Et2O (2 × 5 m l). Th e
com bin ed organ ic fraction s were wash ed with brin e (5 m l) an d dried over an h ydrous
MgSO4. After rem oval of th e solven ts in vacuo, th e residue was purified by colum n ch rom a-
tograph y on silica gel (h exan e/EtOAc 6:1). Th e products were obtain ed as yellowish liquids
in th e yields given below. Th eir spectral data were in agreem en t with th ose publish ed previ-
ously.
(E)-1,4-Diphenylbut-1-en-3-yne (E-2a). Yield 40 m g (78%)15c,20
(E)-1,4-Bis[4-(dimethylamino)phenyl]but-1-en-3-yne (E-2b). Yield 14 m g (19%)10b
(E)-1,4-Bis(4-methoxyphenyl)but-1-en-3-yne (E-2c). Yield 12 m g (18%)9g,20
(E)-1,4-Bis(4-methylphenyl)but-1-en-3-yne (E-2d ). Yield 50 m g (86%)21
(E)-1,4-Bis(4-chlorophenyl)but-1-en-3-yne (E-2e). Yield 40 m g (59%)20
(E)-1,4-Bis[4-(trifluoromethyl)phenyl]but-1-en-3-yne (E-2f). Yield 53 m g (62%)10b,20
(E)-1,4-Bis(4-cyanophenyl)but-1-en-3-yne (E-2g). Yield 14 m g (22%)10b
.
.
.
.
.
.
.
(E)-1,4-Bis(3-methylphenyl)but-1-en-3-yne (E-2h ). Yield 48 m g (83%). 1H NMR: 2.34 s, 3 H;
2.36 s, 3 H; 6.36 d, J = 16.2, 1 H; 6.99 d, J = 16.2, 1 H; 7.11–7.30 m , 8 H. 13C NMR: 21.2,
21.4, 88.7, 91.8, 108.0, 123.2, 123.5, 127.0, 128.2, 128.5, 128.6, 129.1, 129.4, 132.1, 136.3,
138.0, 138.3, 141.3. IR: 3027, 2920, 1582, 1484, 1453, 1091, 1040, 782, 703, 690. HR MS (EI)
for C18H16 calculated: 232.125201, foun d: 232.124879.
(E)-1,4-Bis(3-chlorophenyl)but-1-en-3-yne (E-2i). Yield 44 m g (56%). 1H NMR: 6.36 d, J =
16.2, 1 H; 6.97 d, J = 16.2, 1 H; 7.26–7.46 m , 8 H. 13C NMR: 89.5, 91.0, 109.2, 124.5, 124.9,
126.2, 128.2, 128.7, 129.6, 129.7, 130.0, 131.4, 134.2, 134.8, 137.9, 140.4. IR: 1590, 1561,
1474, 1096, 1077, 950, 881, 804, 782, 709, 702, 681. HR MS (EI) for C16H10Cl2 calculated:
272.015956, foun d: 272.015645.
(E)-1,4-Bis[3-(trifluoromethyl)phenyl]but-1-en-3-yne (E-2j). Yield 21 m g (25%). 1H NMR: 6.44 d,
J = 16.2, 1 H; 7.09 d, J = 16.2, 1 H; 7.45–7.65 m , 6 H; 7.66 s, 1 H; 7.74 s, 1 H. 13C NMR:
89.7, 91.1, 109.6, 123.0, 123.0, 124.1, 124.9, 125.0, 125.3, 125.4, 128.3, 128.4, 128.91,
129.3, 129.4, 134.6, 136.8, 140.5. IR: 1332, 1167, 1128, 1073, 695. HR MS (EI) for C16H10F6
calculated: 340.068670, foun d: 340.068276.
(E)-1,4-Bis(2-methoxyphenyl)but-1-en-3-yne (E-2k). Yield 32 m g (48%)15c,20
(E)-1,4-Bis(2-methylphenyl)but-1-en-3-yne (E-2l). Yield 40 m g (69%)15c,21
(E)-1,4- Bis(2-chlorophenyl)but-1-en-3-yne (E-2m ). Yield 39 m g (57%)22
(E)-1,4-Bis[(2-trifluoromethyl)phenyl]but-1-en-3-yne (E-2n ). Yield 32 m g (44%)20
(E)-1,4-(Diferrocenyl)but-1-en-3-yne (E-1o). Yield 30 m g (29%)20
.
.
.
.
.
[Ru(CHPh )Cl2(PCy3)2]-Catalyzed Dim erization . Gen eral Procedure
Method A. First gen eration Grubbs catalyst (0.025 m m ol, 20.5 m g), alkyn e (0.5 m m ol),
an d water (4 m l) were placed in a vial. SDS (1 m m ol, 288 m g) was th en added, an d th e solu-
tion was stirred at 50 °C for 15 h . Th e reaction m ixture was th en extracted with Et2O (2 ×
5 m l). Th e com bin ed organ ic fraction s were wash ed with brin e (5 m l) an d dried over an h y-
drous MgSO4. After rem oval of th e solven ts in vacuo, th e residue was purified by colum n
ch rom atograph y on silica gel (h exan e/EtOAc 6:1). Th e products were obtain ed as yellowish
liquids in th e yields given below. Th eir spectral data were in agreem en t with th ose pub-
lish ed previously.
Method B. First gen eration Grubbscatalyst (0.025 m m ol, 20.5 m g), alkyn e (0.5 m m ol),
toluen e (0.4 m l), an d water (3.6 m l) were placed in a vial. SDS (1 m m ol, 288 m g) was th en
added, an d th e solution was stirred at 50 °C for 15 h . Th e reaction m ixture was th en ex-
Collect. Czech. Chem. Commun. 2009, Vol. 74, No. 3, pp. 433–442

440
Novák, Kotora:
tracted with Et2O (2 × 5 m l). Th e com bin ed organ ic fraction s were wash ed with brin e (5 m l)
an d dried over an h ydrous MgSO4. After rem oval of th e solven ts in vacuo, th e residue was
purified by colum n ch rom atograph y on silica gel (h exan e/EtOAc 6:1). Th e products were ob-
tain ed as yellowish liquids in th e yields given below. Th eir spectral data were in agreem en t
with th ose publish ed previously.
(Z)- and (E)-1,4-Diphenylbut-1-en-3-yne (Z-2a an d E-2a). Meth ods A an d B 49 m g (96%) an d
50 m g (98%), respectively. Z/E m ixture (5:1)7,15c,20,23
.
(Z)- and (E)-1,4-Bis(4-methylphenyl)but-1-en-3-yne (Z-2d an d E-2d ). Meth od A 55 m g (95%).
Z/E m ixture (10:1). Meth od B 20 m g (34%). Z/E m ixture (20:1)7,9g,10b
(Z)- and (E)-1,4-Bis(4-chlorophenyl)but-1-en-3-yne (Z-2e an d E-2e). Meth od A 31 m g (46%).
Z/E m ixture (19:1). Meth od B 61 m g (90%). Z/E m ixture (10:1)15a,20
(Z)- and (E)-1,4-Bis[4-(trifluoromethyl)phenyl]but-1-en-3-yne (Z-2f an d E-2f). Meth od A 64 m g
(75%). Z/E m ixture (13:1). Meth od B 76 m g (89%). Z/E m ixture (19:1)15a,20,21
.
.
.
(Z)- and (E)-1,4-Bis(3-methylphenyl)but-1-en-3-yne (Z-2h an d E-2h ). Meth od A 38 m g (51%).
Z/E m ixture (5:1). Meth od B 48 m g (83%). Z/E m ixture (7:1). Z-2h . 1H NMR: 2.34 s, 3 H;
2.38 s, 3 H; 5.88 d, J = 12, 1 H; 6.65 d, J = 12, 1 H; 7.21–7.31 m , 6 H; 7.68–7.71 m , 1 H;
7.81 m , 1 H. 13C NMR: 21.2, 21.5, 88.1, 96.0, 107.2, 123.3, 126.0, 128.2, 128.3, 129.2, 129.2,
129.4, 132.0, 136.5, 137.7, 138.1, 138.6. IR: 3032, 2918, 1579, 1489, 1448, 1095, 1038, 786,
707, 685. HR MS (EI) for C18H16 calculated: 232.125201, foun d: 232.124913.
(Z)- and (E)-1,4-Bis(3-chlorophenyl)but-1-en-3-yne (Z-2i an d E-2i). Meth od A 64 m g (94%).
Z/E m ixture (5:1). Meth od B 61 m g (90%). Z/E m ixture (8:1). Z-2i. 1H NMR: 5.93 d, J = 12,
1 H; 6.66 d, J = 12, 1 H; 7.27–7.58 m , 7 H; 8.09 s, 1 H. 13C NMR: 88.8, 95.2, 108.5, 124.8,
127.1, 128.3, 128.5, 128.8, 129.6, 129.6, 129.7, 131.3, 134.2, 134.3, 137.8, 138.0. IR: 1585,
1559, 1468, 1073, 806, 779, 711, 700, 685. HR MS (EI) for C16H10Cl2 calculated: 272.015956,
foun d: 272.015787.
(Z)- and (E)-1,4-Bis[3-(trifluoromethyl)phenyl]but-1-en-3-yne (Z-2j an d E-2j). Meth od A 31 m g
(38%). Z/E m ixture (10:1). Meth od B 49 m g (58%). Z/E m ixture (17:1). Z-2j. 1H NMR:
6.01 d, J = 12, 1 H; 6.77 d, J = 12, 1 H; 7.47–7.83 m , 7 H; 8.43 s, 1 H. 13C NMR: 88.8, 95.2,
108.8, 123.9, 124.9, 124.9, 125.1, 125.2, 128.3, 128.4, 128.9, 129.0, 131.5, 131.9, 132.2,
134.5, 136.9, 137.9. IR: 1336, 1175, 1131, 1085, 689. HR MS (EI) for C16H10F6 calculated:
340.068670, foun d: 340.068309.
(Z)- and (E)-1,4-Bis(2-methylphenyl)but-1-en-3-yne (Z-2l an d E-2l). Meth od A 23 m g (40%).
Z/E m ixture (2:1). Meth od B 41 m g (71%). Z/E m ixture (4:1)15c,21
.
(Z)- and (E)-1,4-Bis(2-chlorophenyl)but-1-en-3-yne (Z-2m an d E-2m ). Meth od A 46 m g (68%).
Z/E m ixture (4:1). Meth od B 12 m g (18%). Z/E m ixture (5:1)15c,22
.
(Z)- and (E)-1,4-Bis[2-(trifluoromethyl)phenyl]but-1-en-3-yne (Z-2n an d E-2n ). Meth od A 56 m g
(66%). Z/E m ixture (10:1). Meth od B 24 m g (28%). Z/E m ixture (3:1). Z-2n . 1H NMR: 5.93 d,
J = 11.7, 1 H; 6.66 d, J = 11.7, 1 H; 7.27–7.39 m , 6 H; 7.48–7.49 m , 1 H; 8.09–8.10 m , 1 H.
13C NMR: 88.8, 95.2, 108.5, 124.8, 127.1, 128.3, 128.6, 128.8, 129.6, 129.6, 129.7, 131.3,
134.2, 134.3, 137.8, 138.0. IR: 1340, 1173, 1119, 1085, 693. HR MS (EI) for C16H10F6 calcu-
lated: 340.068670, foun d: 340.06915821
(Z)- and (E)-1,4-Di(ferrocenyl)but-1-en-3-yne (Z-2o an d E-2o). Meth od B 31 m g (30%). Z/E
m ixture (1:1)20,23
.
.
Collect. Czech. Chem. Commun. 2009, Vol. 74, No. 3, pp. 433–442

Rh- and Ru-Complex-Catalyzed Dimerization of Arylethynes
441
This work was supported by the Ministry of Education, Youth and Sports of the Czech Republic
(projects LC06070 and MSM 0021620857).
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