Stereoselective synthesis of enynes by nickel-catalyzed cross-coupling of divinylic chalcogenides with alkynes

Article abstract of DOI:10.1021/jo0261707

(Z,Z)- and (E,E)-divinylic selenides and telurides undergo direct coupling with terminal alkynes in the presence of a nickel/CuI catalyst at room temperature to give (Z)- and (E)-enyne systems in good yields and with complete retention of configuration.

Full text of DOI:10.1021/jo0261707

alkenyliodonium salts9 and vinyl iodides10 and by the
coupling of 1-silylacetylenes with vinyl halides and
triflates.11 The use of vinylic chalcogenides to obtain
enyne and enediyne systems has been previously de-
scribed,12 and many other important applications of
vinylic selenides and vinylic tellurides have also been
reported.13 However, just a few of them involved (Z,Z)-
divinylic tellurides, while similar applications of (E,E)-
divinylic tellurides and selenides are virtually unknown.
In this way, (Z,Z)-divinylic tellurides undergo, in a
stereoselective manner, transmetalation reactions to give
vinyllithium14 and vinylcopper12a,d,15 species, useful in-
termediates for further reactions with electrophiles. They
have also been converted to the corresponding coupling
products by reaction with lower order cyanocuprates16
and to cross-coupling17 and homocoupling products (1,4-
diaryl-1,3-butadienes) by treatment with palladium cata-
lysts.18
Ster eoselective Syn th esis of En yn es by
Nick el-Ca ta lyzed Cr oss-Cou p lin g of
Divin ylic Ch a lcogen id es w ith Alk yn es
Claudio C. Silveira,* Antonio L. Braga,
Adriano S. Vieira, and Gilson Zeni*
Departamento de Quı´mica, Universidade Federal de Santa
Maria, C. P. 5001, CEP 97105-900, Santa Maria, RS, Brazil
silveira@quimica.ufsm.br
Received J uly 9, 2002
Abstr a ct: (Z,Z)- and (E,E)-divinylic selenides and telurides
undergo direct coupling with terminal alkynes in the pres-
ence of a nickel/CuI catalyst at room temperature to give
(Z)- and (E)-enyne systems in good yields and with complete
retention of configuration.
Recently, we accomplished the stereospecific formation
of (Z)-enyne systems by the palladium-catalyzed cross-
coupling reaction of (Z,Z)-divinyl tellurides with 1-al-
kynes.19 Although, in all cases, an excess of alkyne has
been used, the transfer of only one vinylic group was
observed. Divinylic selenides were totally inert under
these coupling conditions, employing several different
palladium catalysts, and the starting materials have
usually been recovered unchanged. Herein we report a
more general approach of this method for the direct
synthesis of (Z)- and (E)-enyne systems via a nickel-
catalyzed cross-coupling reaction of (Z,Z)- and (E,E)-
divinylic chalcogenides with 1-alkynes. In this method,
Conjugated enynes are of great interest in organic
synthesis. Calicheamicins, esperamicins, and dynemycins
are members of a newly emerged class of antibiotic
molecules that was discovered recently. They are con-
sidered to be some of the most potent antitumoral agents
known to date and have other interesting biological
activities as well.1,2 The synthesis of enynes has received
special attention during the last 20 years, and new
methods for their preparation from vinyl halides or vinyl
organometallic compounds have been recently developed.
The cross-coupling of vinyl bromides, iodides, chlorides,
and triflates with monosubstituted acetylenes has been
achieved in the presence of a Pd0 or PdII/CuI catalyst
using an amine as a base.3 The synthesis of enynes has
also been performed using the coupling reaction of
bromoalkynes with vinylmetals such as vinyl boron,4
-copper,5 -zinc,6 -aluminum,7 or -magnesium reagents8 by
the copper-catalyzed coupling reaction of alkynes with
(9) Kang, S.-K.; Yoon, S.-K.; Kim, Y.-M. Org. Lett. 2001, 3, 2697.
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De Araujo, M. A.; Comasseto, J . V. Synlett 1995, 1145. (e) Zeni, G.;
Comasseto, J . V. Tetrahedron Lett. 1999, 40, 4619. (f) Braga, A. L.;
Zeni, G.; Andrade, L. H.; Silveira, C. C.; Stefani, H. A. Synthesis 1998,
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H.; Lee, S. H. J . Chem. Res. 2001, 283.
* Phone/Fax: 0055(55)2208754.
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Stang, P. J ., Diederich, F., Eds.; VCH: Weinheim, 1995.
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D. Tetrahedron 1996, 52, 6453. (b) Nicolaou, K. C.; Da´ı, W. M. Angew.
Chem., Int. Ed. Engl. 1991, 30, 1387. (c) Nicolaou, K. C.; Da´ı, W.-D.;
Hong, Y. P.; Tsay, S.-C.; Baldridge, J . S.; Siegel, J . S. J . Am. Chem.
Soc. 1993, 115, 7944. (d) Danishefsky, S. J .; Shair, M. D. J . Org. Chem.
1996, 61, 16. (e) Yang, C.; Nolan, S. P. J . Org. Chem. 2002, 67, 591
and references therein.
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1975, 4467. (b) Alami, M.; Linstrumelle, G. Tetrahedron Lett. 1991,
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10.1021/jo0261707 CCC: $25.00 © 2003 American Chemical Society
Published on Web 12/21/2002
662
J . Org. Chem. 2003, 68, 662-665

TABLE 1. Syn th esis of En yn es by Cr oss-Cou p lin g
Rea ction of Divin ylic Ch a lcogen id es w ith 1-Alk yn es
SCHEME 1
SCHEME 2
substrate
alkyne R1
n-pentyl
Ph
CH2OH
CH2CH2CH2OH
n-pentyl
Ph
enyne time (h) yielda (%)
1
2
3
4
5
6
7
8
9
(Z,Z)-1
(Z,Z)-1
(Z,Z)-1
(Z,Z)-1
(E,E)-2
(E,E)-2
(E,E)-2
(E,E)-2
(Z,Z)-3
6
7
20
16
20
20
20
16
15
20
20
20
16
22
22
20
20
20
20
24
78
61
73
72
57
72
81
68
61
54
56
76
71
63
75
83
71
61
8
9
the transfer of both vinylic groups linked to the chalcogen
atom was observed, as summarized in Scheme 1.
The initial studies were focused on the development
of an optimum set of reaction conditions for the coupling
reaction of divinylic chalcogenides with terminal alkynes.
In preliminary experiments, we investigated the cata-
lyzed cross-coupling between (Z,Z)-distyryl telluride 1
(1 equiv) and 2-propyn-1-ol (4 equiv) in pyrrolidine, at
room temperature (Scheme 2).
10
11
12
13
6
7
8
9
10
11
12
13
14
15
CH2OH
CH2CH2CH2OH
n-pentyl
Ph
10 (Z,Z)-3
11 (Z,Z)-3
12 (Z,Z)-3
13 (E,E)-4
14 (E,E)-4
15 (E,E)-4
16 (E,E)-4
17 (Z,Z)-5
18 (Z,Z)-5
CH2OH
CH2CH2CH2OH
n-pentyl
Ph
CH2OH
The influence of the nature of the catalyst is note-
worthy. When the reaction was performed in pyrrolidine
using PdCl2(PhCN)2, Pd(OAc)2, PdCl2, PdCl2/PPh3, PdCl2-
(PPh3)2, Pd(PPh3)4, or Pd(PPh3)4/CuI, no coupling product
was isolated. The change of the catalyst to Ni(PPh3)2Cl2
gave the desired enynes in unsatisfactory yields (20-
40%), depending on the amount of catalyst used (1-5 mol
%). However, using Ni(dppe)Cl2 (5 mol %), in the presence
of a copper salt (CuI, 5 mol %), afforded enyne (Z)-5 in
77% isolated yield. Lower yields were obtained in the
presence of other solvents or mixtures of solvents such
as THF, DMF, CH3CN, CH2Cl2, THF/methanol, benzene,
and DMF/methanol. Thus, the optimum conditions for
coupling according to Scheme 1 were stablished to be the
use of Ni(dppe)Cl2 (5 mol %), CuI (5 mol %), pyrrolidine
(10 mL), divinyl chalcogenide (1 mmol), and the ap-
propriate 1-alkyne (4 mmol) at room temperature. More-
over, the coupling reaction was then extended to other
divinylic chalcogenides 2-4 and alkynes. Fortunately,
this condition proved to be efficient for the (E,E)-isomers
of selenium and tellurium derivatives and also for the
(Z,Z)-divinyl selenide. The results are summarized in
Table 1.
The reaction was equally successful with the divinylic
telluride 5, a substrate containing free OH groups. The
cross-coupling reaction of 5 with 1-heptyne and 2-methyl-
3-butyn-2-ol gave the corresponding enynes 14 and 15
in good yields (entries 17 and 18, Table 1).
Noteworthy is the efficiency of this coupling reaction
using a nickel catalyst. To our knowledge, this reaction
is one of the first examples of an efficient cross-coupling
reaction involving a terminal alkyne catalyzed by nickel,
since in almost all examples described to date, only
palladium catalysts have been used with efficiency.3h,20
Also, all described examples of efficient cross-coupling
involving vinylic tellurides have utilized palladium cata-
lysts (in up to 20 mol % of catalyst), while alkyl or aryl
Grignard reagents have been shown to couple with vinylic
CH2CH2CH2OH
n-pentyl
C(CH3)2OH
a
Yield of isolated pure product.
selenides in the presence of nickel catalysts.21 The
advantages of the nickel system include its air stability,
lower cost, and ease of preparation of the catalyst, all of
which are important when considering the scale-up of a
reaction.
Analysis of the H NMR and 13C NMR spectra showed
1
that all the enyne compounds presented data in full
agreement with their assigned structures. The stereo-
chemistry of the obtained enynes was easily established.
As an example, the 1H NMR spectrum of compound 6
showed a double triplet at 5.69 ppm with coupling
constants of 11.8 and 2.4 Hz, typical of a cis hydrogen.
The other vinylic hydrogen resonates at 6.54 ppm as a
doublet, with a coupling constant of 11.8 Hz. The stere-
oisomeric purities of enynes 6-9 were similar to that of
starting divinylic telluride 1, due to a complete retention
of configuration in this type of reaction. If the reactions
were performed with pure (E,E)- or (Z,Z)-isomers, pure
(E)- or (Z)-enynes were isolated in all cases. By using an
enriched mixture such as 95:5 , the same ratio was
observed in the final product. The only exception was
observed with the coupling of (Z,Z)-isomers 1 and 3 with
phenylacetylene. Under the experimental conditions
employed, isomerization of enyne 7 occurred, and the
same 93:7 mixture of (Z/ E)-isomers was isolated, starting
with either telluride 1 or selenide 3.
The starting divinylic chalcogenides have been pre-
pared by procedures previously described or by methods
under study in our laboratory. In this way, (Z,Z)-divinylic
(21) Okamura, H.; Miura, M.; Kosugi, K.; Takei, H. Tetrahedron Lett.
1980, 21, 87. Tingoli, M.; Tiecco, M.; Testaferri, L.; Temperini, A.;
Pelizzi, G.; Bacci, A Tetrahedron 1995, 51, 4691. Tingoli, M.; Tiecco,
M.; Testaferri, L.; Chianelli, D. Gazz. Chim. Ital. 1991, 121, 59. Hevesi,
L.; Hermans, B.; Allard, C. Tetrahedron Lett. 1994, 36, 6729. Gerard,
J .; Hevesi, L. Tetrahedron 2001, 57, 9109.
(20) Furber, M. In Comprehensive Organic Functions Group Trans-
formations; Katritzky, A. R., Meth-Cohn, O., Rees, C. W., Eds.;
Pergamon: Oxford, 1995; Vol. 1.
J . Org. Chem, Vol. 68, No. 2, 2003 663

bath. The reaction was stirred at room temperature for 20 h.
The solids were filtered off over Celite; the filtrate was treated
with a saturated solution of NH4Cl and extracted with ethyl
acetate, and the organic layers were dried over MgSO4 and
concentrated in vacuo. Column chromatography (hexanes) of the
residue gave (Z)-6 as a pale yellow oil (0.308 g, 78%): IR (neat,
cm-1) 3061, 3021, 2200, 1660, 1450, 784, 692; 1H NMR (CDCl3)
δ 7.85 (d, J ) 6.8 Hz, 2H), 7.37-7.20 (m, 3H), 6.54 (d, J ) 11.8
Hz, 1H), 5.69 (dt, J ) 11.8, 2.4 Hz, 1H), 2.43 (td, J ) 8.0, 2.0
Hz, 2H), 1.63-1.33 (m, 6H), 0.91 (t, J ) 6.8 Hz, 3H); 13C NMR
(CDCl3) δ 137.18, 136.70, 128.41, 128.10, 128.07, 108.20, 97.80,
79.20, 31.14, 28.27, 22.21, 19.84, 13.94; EIMS m/z (rel int) 198
(25), 155 (20), 141 (100), 91 (27), 79 (12); HRMS calcd for C15H18
198.1408, found 198.1417.
telluride 1 was prepared by the reaction of phenyl
acetylene with a solution of sodium telluride, generated
in situ, in 79% isolated yield.12a,15b The (E,E)-isomers were
prepared by Na2Y (Y ) Se, Te) vinylic substitution of (E)-
â-bromostyrene (70 and 82% yields, respectively).22 Using
a commercially available (∼9:1) E/ Z mixture of isomers
of bromostyrene allowed the pure (E,E)-isomer to be
isolated after column chromatography and washing with
petroleum ether or by starting with the pure (E)-â-
bromostyrene, easily available by recently described
procedures.23 (Z,Z)- and (E,E)-divinylic selenides are also
available by a procedure published some years ago,
involving the reaction of (Z)- and (E)-â-styryl selenide
anions, generated in situ, with (Z)- and (E)-â-bromo-
styrene, respectively.24 Otherwise, we prefer to prepare
these species by a method under investigation in our
laboratory. (Z,Z)-Divinylic selenide 3 was obtained by the
reaction of phenylacetylene with Na2Se, in 71% isolated
yield, in a procedure similar to the one used for the
preparation of the divinyl tellurium derivative (E,E)-
2.12a,15b We observed that the use of 1-propanol instead
of ethanol in this reaction was necessary and allows for
easy entry to this class of compounds.25
In summary, we have explored a new Ni/CuI-catalyzed
cross-coupling reaction of the (Z,Z)- and (E,E)-divinylic
chalcogenides with alkynes and established a new ste-
reoselective route to (Z)- and (E)-enynes in good yields.
Our approach is an improvement of the described meth-
ods, since it avoids the preparation of vinylmetals and
haloalkynes and requires no protection of the hydroxyl
group in propargylic alcohol. In comparison to our previ-
ously described method, the present procedure has
advantages such as the easy access and the great stability
of the divinylic chalcogenides and the transfer of both of
the vinylic units.
(Z)-1,4-Dip h en yl-1-bu ten -3-yn e (7):26 oil; IR (neat, cm-1
)
3060, 3022, 2184, 1594, 1448, 1441; 1H NMR (CDCl3) δ 7.90 (d,
J ) 8.0 Hz, 2H); 7.49-7.22 (m, 8H), 6.65 (d, J ) 12.0 Hz, 1H),
5.89 (d, J ) 12.0 Hz, 1H); 13C NMR (CDCl3) δ 138.64, 136.5,
131.42, 128.73, 128.48, 128.38, 128.34, 128.26, 123.42,107.35,
95.83, 88.22; EIMS m/z (rel int) 204 (base), 203 (95), 202 (97),
101 (50), 89 (16), 76 (15), 63 (7), 51 (7).
(Z)-5-P h en yl-4-p en ten -2-yn -1-ol (8): oil; IR (neat, cm-1
)
3329, 3023, 2860, 1951, 1899, 1598, 1492; 1H NMR (CDCl3) δ
7.81 (d, J ) 8.0 Hz, 2H), 7.39-7.23 (m, 3H), 6.64 (d, J ) 12.0
Hz, 1H), 5.71 (dt, J ) 12.0, 2.0 Hz, 1H), 4.46 (s, 2H), 2.27 (s,
1H); 13C NMR (CDCl3) δ 139.10, 136.14, 128.53, 128.51, 128.36,
106.68, 93.80, 83.98, 51.65; EIMS m/z (rel int) 158 (53), 140 (41),
129 (95), 128 (100), 127 (40), 115 (38), 102 (11), 77 (18), 63 (23),
51 (27); HRMS calcd for C11H10O 158.0731, found 158.0737.
(Z)-7-P h en yl-6-h ep ten -4-yn -1-ol (9):27 oil; 1H NMR (CDCl3)
δ 7.83 (d, J ) 8.2 Hz, 2H), 7.37-7.21 (m, 3H), 6.54 (d, J ) 11.8
Hz, 1H), 5.67 (dt, J ) 11.8, 2.4 Hz, 1H), 3.73 (t, J ) 6.2 Hz, 2H),
2.53 (td, J ) 6.9, 2.4 Hz, 2H), 2.05 (s, 1H), 1.81 (quint., J ) 6.6
Hz, 2H); 13C NMR (CDCl3) δ 137.51, 136.50, 129.47, 128.64,
128.31, 107.85, 96.53, 79.49, 61.42, 31.14, 16.51; EIMS m/z (rel
int) 186 (52), 167 (27), 155 (28), 153 (56), 141 (85), 129 (50), 128
(48), 115 (100), 91 (35), 77 (20), 63 (23), 51 (22); HRMS calcd for
C
13H14O 186.1044, found 186.1051.
(E)-1-P h en yl-1-n on en -3-yn e (10):10b oil; IR (neat, cm-1
)
2956, 2932, 2859, 2210, 1704, 1596, 1449;1H NMR (CDCl3) δ
7.35-7.21 (m, 5H), 6.85 (d, J ) 16.0 Hz, 1H), 6.14 (dt, J ) 16.0,
2.1 Hz, 1H), 2.34 (td, J ) 6.0, 2.0 Hz, 2H), 1.59-1.35 (m, 6H),
0.91 (t, J ) 7.1 Hz, 3H), 13C NMR (CDCl3) δ 139.88, 136.60,
128.57, 128.11, 125.98, 108.93, 92.99, 79.72, 31.11, 28.49, 22.20,
19.59, 13.93; EIMS m/z (rel int) 198 (36), 169 (11), 155 (23), 141
(100), 115 (61), 91 (36), 79 (14).
Exp er im en ta l Section
Gen er a l Meth od s. 1H and 13C NMR spectra were recorded
in CDCl3 at 200 or 50 MHz, respectively. Melting points are
uncorrected. HRMS were obtained at Central Analı´tica, Instituto
de Qu´ımica, UNICAMP, or Universidade de Sa˜o Paulo, SP,
Brazil. All reagents and solvents were dried and purified before
use by the usual procedures prior to use. Column chromatog-
raphy was carried out on 230-400 mesh silica gel.
(Z)-1-(1-Non en )-3-yn ylb en zen e (6). Typ ica l P r oced u r e
for th e Cou p lin g of (Z,Z)-Bis-styr yltellu r id e ((Z)-1) w ith
1-Alk yn e. To a two-necked 25 mL round-bottomed flask under
an argon atmosphere containing Ni(dppe)Cl2 (0.026 g, 5 mol %),
CuI (0.01 g, 5 mol %), and dry pyrrolidine (1.5 mL) was added
(Z,Z)-1 (0.33 g, 1.0 mmol). After the mixture was stirred for 15
min at room temperature, 1-heptyne (0.38 g, 4.0 mmol) was
added. An exothermic reaction was observed, and the temper-
ature was maintained between 15 and 20 °C by using a water
(E)-1,4-Dip h en yl-1-bu ten -3-yn e (11): mp 97-98°C (lit. 12h
96-97 °C).
(E)-5-P h en yl-4-p en ten -2-yn -1-ol (12):10b oil; IR (neat, cm-1
)
3369, 3027, 2923, 2208, 1732, 1689, 1597, 1492, 1448; 1H NMR
(CDCl3) δ 7.36-7.21 (m, 5H), 6.95 (d, J ) 16.0 Hz, 1H), 6.16
(dt, J ) 16.0, 4.0 Hz, 1H), 4.43 (d, J ) 2.0 Hz, 2H), 2.06 (s, 1H);
13C NMR (CDCl3) δ 141.81, 135.95, 128.62, 128.54, 126.23,
107.37, 89.40, 84.80, 51.52; EIMS m/z (rel int) 158 (52), 140 (37),
128 (100), 127 (40), 115 (43), 102 (12), 77 (20), 63 (20), 51 (29).
(E)-7-P h en yl-6-h ep ten -4-yn -1-ol (13):28 oil; IR (neat, cm-1
)
3343, 3026, 2946, 2211, 1598, 1491, 1446; 1H NMR (CDCl3) δ
7.32-7.20 (m, 5H), 6.86 (d, J ) 16.0 Hz, 1H), 6.12 (dt, J ) 16.0,
4.0 Hz, 1H), 3.76 (t, J ) 6.0 Hz, 2H), 2.48 (td, J ) 8.0, 4.0 Hz,
2H), 2.09 (s, 1H), 1.80 (quint., J ) 8.0 Hz, 2H); 13C NMR (CDCl3)
δ 140.22, 136.34, 128.54, 128.19, 125.96, 108.49, 91.81, 80.19,
61.50, 31.30, 14.86; EIMS m/z (rel int) 186 (65), 167 (29), 155
(30), 153 (57), 142 (98), 141 (89), 130 (34), 129 (51), 128 (49),
115 (base), 91 (40), 77 (20), 63 (21), 51 (20); HRMS calcd for
C13H14O 186.1044, found 186.1019.
(22) Unpublished results from our laboratory. See also: Silveira,
C. C.; Perin, G.; Boeck, P.; Braga, A. L.; Petragnani, N. J . Organomet.
Chem. 1999, 584, 44.
(23) (a) Kuang, C.; Senboku, H.; Tokuda, M. Tetrahedron Lett. 2001,
42, 3893. (b) Kuang, C.; Senboku, H.; Tokuda, M. Synlett 2000, 1439.
(c) Chowdhury, S.; Roy, S. J . Org. Chem. 1997, 62, 199.
(24) Testaferri, L.; Tiecco, M.; Tingoli, M.; Chianelli, D. Tetrahedron
1986, 42, 63.
(Z)-Dec-2-en -4-yn -1-ol (14): oil; spectroscopic data were in
good agreement with the literature.3f
(2Z)-6-Meth ylh ep t-2-en -4-yn e-1,6-d iol (15): oil; IR (neat,
cm-1) 3351, 2918, 2851, 1736, 1455, 1369, 1240, 1159, 1026, 940;
1H NMR (CDCl3) δ 6.07 (dt, J ) 10.8, 6.3 Hz, 1H), 5.60 (d, J )
10.8 Hz, 1H), 4.38 (dd, J ) 6.5, 1.2 Hz, 2H), 2.12 (s, 2H), 1.54 (s,
6H); 13C NMR (CDCl3) δ 141.4, 110.1, 100.0, 73.3, 65.2, 60.4,
31.2; HRMS calcd for C8H12O2 140.0837, found 140.0834.
(25) Unpublished results from our laboratory.
(26) Galli, C.; Gentili, P.; Rappoport, Z. J . Org. Chem. 1994, 59, 6786.
(27) Zeni, G.; Comasseto, J . V. Tetrahedron Lett. 1999, 40, 4619.
(28) Blade, R. J .; Robinson, J . E.; Peek, R. J .; Weston, J . B.
Tetrahedron Lett. 1987, 3857.
664 J . Org. Chem., Vol. 68, No. 2, 2003

Su p p or tin g In for m a tion Ava ila ble: Analytical data for
compounds 11 and 14 and 1H and 13C NMR spectra of
compounds 6-15. This material is available free of charge via
the Internet at http://pubs.acs.org.
Ack n ow led gm en t. The authors acknowledge the
financial support provided by FAPERGS, CNPq, and
CAPES. We also thank Profs. P. Bakuzis and R. A. Pilli
for their sugestions and Central Anal´ıtica, IQ, UNI-
CAMP, for providing some HRMS.
J O0261707
J . Org. Chem, Vol. 68, No. 2, 2003 665