Convenient synthesis of (1-propynyl)arenes through a one-pot double elimination reaction, and their conversion to enynes

Article abstract of DOI:10.1055/s-2007-984532

A series of (1-propynyl)arenes were prepared by one-pot double elimination reaction of ethyl sulfone, aromatic aldehyde and chloro diethylphosphate in THF with a base such as BuLi and t-BuOK. A propargyllithium which was prepared by treatment of (1-propynyl)arene with BuLi in the presence of 1,3-dimethyl-3,4,5, 6-tetrahydro-2(1H)-pyrimidinone (DMPU) reacted with aromatic aldehyde, chloro diethylphosphate and t-BuOK to afford (4-arylbut-3-en-1-ynyl)arene. Photoluminescence of the enynes thus prepared was recorded both in solution and in the solid state. Georg Thieme Verlag Stuttgart.

Full text of DOI:10.1055/s-2007-984532

LETTER
1909
Convenient Synthesis of (1-Propynyl)arenes through a One-Pot Double
Elimination Reaction, and Their Conversion to Enynes
C
onvenient Synthe
e
sis of (1-P
-
La
renes ie An,*a Zhiyang Zhang,a,b Akihiro Orita,*b Hidetaka Mineyama,b Junzo Otera*a,b
a
Department of Chemistry, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, P. R. of China
Fax +86(731)8827944; E-mail: deliean@sina.com
b
Department of Applied Chemistry, Okayama University of Science, Ridai-cho, Okayama 700-0005, Japan
Fax +81(86)2564292; E-mail: orita@high.ous.ac.jp; E-mail: otera@high.ous.ac.jp
Received 2 May 2007
In memory of the late Professor Yoshihiko Ito
alkyne
metathesis
Abstract: A series of (1-propynyl)arenes were prepared by one-pot
double elimination reaction of ethyl sulfone, aromatic aldehyde and
chloro diethylphosphate in THF with a base such as BuLi and
t-BuOK. A propargyllithium which was prepared by treatment of
(1-propynyl)arene with BuLi in the presence of 1,3-dimethyl-
3,4,5,6-tetrahydro-2(1H)-pyrimidinone (DMPU) reacted with aro-
matic aldehyde, chloro diethylphosphate and t-BuOK to afford (4-
arylbut-3-en-1-ynyl)arene. Photoluminescence of the enynes thus
prepared was recorded both in solution and in the solid state.
Ar
Me
Ar
Ar
Me
Me
Equation 1
Sonogashira
coupling
+
ArX
Me
Ar
Me
Key word: alkynes, sulfones, aldehydes, eliminations, enynes
Equation 2
base
RCHO
ClP(O)(OEt)2
We have long been engaged in the double elimination re-
action of b-substituted sulfones, by which a facile one-pot
process for the synthesis of various aromatic acetylenes
involving mono-, di-, and triyne components has been
achieved.1 Since the acetylenes thus obtained were termi-
nated only by aromatic or trialkylsilyl groups, we became
interested in further diversification of the terminal groups.
Among them, termination with a methyl group seemed to
us of great use because of the following reasons. First, for
alkyne metathesis, which has been receiving increasing
attention,2 (1-propynyl)arenes are best employed to bias
the reaction in the favored direction as a result of facile
release of the co-product 2-butyne from the equilibrium
system (Equation 1). However, preparation of (1-propyn-
yl)arenes suffers from inconvenience, because gaseous
propyne should be manipulated for Sonogashira coupling
with aryl halides (Equation 2).3 Second, we postulated
that the methylethyne component must be readily metal-
lated upon treatment with an organometallic base, so that
reaction of the in situ generated propargylic anion with
aldehydes could provide a one-pot procedure to produce
enynes (Equation 3). Herein, we show that the double
elimination protocol is indeed effective for convenient
synthesis of (1-propynyl)arenes without use of propyne.
Moreover, the (1-propynyl)arenes thus obtained were
transformed into enynes, which are another novel motif
for electronics materials.
Ar
Ar
R
Ar
Me
R
(EtO)2(O)PO
Equation 3
The methyl termination was realized by use of ethyl
phenyl sulfone (1). Thus, according to the standard double
elimination procedure, 1 was treated sequentially with
BuLi, aldehyde 2, ClP(O)(OEt)2, and t-BuOK in one-pot
manner4 to afford the desired (1-propynyl)arenes 3 as
shown in Scheme 1. A variety of (1-propynyl)arenes were
obtained. The yields are satisfactory if it is taken into
account that several consecutive reactions are involved in
this procedure, i.e., metallation, aldol-type reaction, eno-
late trapping, and double elimination (Scheme 2). The
methoxy group was employable and halogens remained
intact.4a Not only simple phenylacetylenes but also other
aromatics such as naphthyl, thienyl, ferrocenyl, and
(phenylethynyl)phenyl derivatives were obtained.
(1) BuLi
(2) ArCHO 2
(3) ClP(O)(OEt)2
(4) t-BuOK
EtSO2Ph
Me
Ar
THF
1
3
BuLi
t-BuOK
– PhSO2H
ArCHO 2
ClP(O)(OEt)2
PhSO2
Ar
PhSO2
Me
Ar
t-BuOK
– (EtO)2PO2H
Me
OP(O)(OEt)2
SYNLETT 2007, No. 12, pp 1909–1912
2
4
.0
7
.2
0
0
7
Advanced online publication: 27.06.2007
DOI: 10.1055/s-2007-984532; Art ID: U04407ST
© Georg Thieme Verlag Stuttgart · New York
Scheme 1

1910
D.-L. An et al.
LETTER
(1) BuLi
Upon treatment of 3 with BuLi in the presence of 1,3-di-
methyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (DMPU),
the corresponding propargylic anion was generated
smoothly. To this solution were added aldehyde, ClP(O)
(OEt)2, and t-BuOK successively. After aqueous workup,
the desired enynes 4 were obtained in reasonable yields.
Although the C=C bond formation is usually carried out
by Wittig reaction5 or McMurry coupling,6 the present
method is more convenient because neither Wittig re-
agents nor titanium reagent is necessary.
(2) ArCHO 2
(3) ClP(O)(OEt)2
(4) t-BuOK
EtSO2Ph
Me
Ar
THF
3
1
Ar isolated yield (%)
Ar isolated yield (%)
Ph (3a) 70%
m-MeOC6H4 (3b) 69%
p-MeOC6H4 (3c) 83%
*
o-(3l) 53%
m-(3m) 72%
p-(3n) 78%
2,5-dimethoxyphenyl (3d) 69%
o-BnOC6H4 (3e) 69%
A number of photoluminescence studies have been report-
ed on arenes connected with vinyl and ethynyl moieties,7
but few with enynes. We present here the preliminary
results of UV–Vis. and photoluminescence spectra of the
enynes obtained above. Upon reprecipitation of 4 from
hot hexane, the E-isomers precipitated first followed by
the E/Z mixtures, and, hence, the pure E-isomers were
subjected to spectroscopic investigations. The UV–Vis
spectra of 4a–c exhibited strong bands at around 340 nm
(Table 1). A strong and medium emission band was ob-
served for 4c and 4a, respectively, in CH2Cl2, while 4b
was almost nonemissive (Figure 1). This is in parallel
with the quantum yields (Table 2). Notably, 4a and 4b in
the solid state gave higher quantum yields than in solu-
tion. This is of great promise for designing electronic
devices.
o-BrC6H4 (3f) 72%
p-BrC6H4 (3g) 68%
o-IC6H4 (3h) 65%
2-naphthyl (3i) 74%
ferrocenyl (3j) 60%
*
o-(3o) 50%
m-(3p) 47%
p-(3q) 43%
O
(3k) 61%
O
*
Br
S
Scheme 2
Notably, bis(1-propynyl) derivatives were also accessible,
and these may be employed for ring-closing and polymer-
ization metathesis. Next, the (1-propynyl)arenes thus ob-
tained were subjected to another one-pot procedure Table 2 Photochemical Data of 4a–c in Solution and in the Solid
State
involving aldol-type reaction followed by elimination to
provide enynes (Table 1).
lmax
Compound UV–Visa
(nm)
PL in CH2Cl2
(nm)
PL in the solid statec
(nm)
b,c
Table 1 Aldol-Type Reaction of (1-Propynyl)arenes to Enynes
(1) BuLi, DMPU
(2) Ar'CHO
4a
4b
4c
331
341
341
367 (0.13)
402 (0.02)
377 (0.58)
408 (0.55)
412 (0.22)
429 (0.50)
(3) ClP(O)(OEt)2
(4) t-BuOK
Ar
Ar
Me
Ar'
THF
4
3
t-BuOK
BuLi
DMPU
– (EtO)2PO2H
a In CH2Cl2 (1.9 × 10–4 M).
b In CH2Cl2 (9.4 × 10–7 M).
Ar'CHO
ClP(O)(OEt)2
Ar
c Quantum yields are shown in parentheses.
-
Ar'
Ar
(EtO)2P(O)O
Ar
Ar¢
Yield
(E:Z)
2-naphthyl
2-naphthyl
Ph
4a 63 (5:1)
4b 61 (6:1)
4c 68 (2:1)
p-MeOC6H4
Ph
*
*
2-naphthyl
2-naphthyl
Ph
4d 65 (4:1)
4e 74 (1:1)
*
4f 52 (3:1)
MeO
*
Figure 1 Emission of 4a–c in CH2Cl2 (9.4 × 10–7 M)
Synlett 2007, No. 12, 1909–1912 © Thieme Stuttgart · New York

LETTER
Convenient Synthesis of (1-Propynyl)arenes
1911
was stirred at r.t. for 3 h. t-BuOK (561.1 mg, 5.0 mmol) was
added at –78 °C, and the mixture was stirred at r.t. for 15 h.
After usual workup with EtOAc and aq NH4Cl solution, the
organic layer was evaporated, and the residue was subjected
to column chromatography on silica gel to give 2-(1-prop-
ynyl)naphthalene (3i) as a white powder (123.0 mg, 74%).
2-(1-Propynyl)naphthalene (3i): mp 30–31 °C. 1H NMR
(500 MHz, CDCl3): d = 2.10 (s, 3 H), 7.44–7.49 (m, 3 H),
7.74–7.80 (m, 3 H), 7.90 (s, 1 H). 13C NMR (125 MHz,
CDCl3): d = 4.4, 80.1, 86.2, 121.3, 126.2, 126.3, 127.5,
127.6, 127.8, 128.6, 131.0, 132.4, 133.0.
In summary, the double elimination protocol has proved
to be effective for facile synthesis of (1-propynyl)arenes8
which are otherwise rather inconvenient to prepare. The
(1-propynyl)arenes thus obtained can be transformed into
enynes by one-pot addition–elimination reactions. Thus,
combination of two one-pot reactions offers a new route
for enynes without use of transition-metal catalysts. The
enynes free from transition-metal contamination will find
practical uses in electronic devices. The applications
along this line are now in progress in our group.
(1-Propynyl)benzene (3a): colorless oil. 1H NMR (500
MHz, CDCl3): d = 2.06 (s, 3 H), 7.27–7.29 (m, 3 H), 7.38–
7.40 (m, 2 H). 13C NMR (125 MHz, CDCl3): d = 4.3, 79.7,
85.8, 124.0, 127.5, 128.2, 131.5.
Acknowledgment
1-Methoxy-3-(1-propynyl)benzene (3b): yellow oil. 1H
NMR (500 MHz, CDCl3): d = 2.04 (s, 3 H), 3.77 (s, 3 H),
6.82 (d, J = 8.2 Hz, 1 H), 6.92 (s, 1 H), 6.98 (d, J = 7.7 Hz,
1 H), 7.18 (t, J = 7.9 Hz, 1 H). 13C NMR (125 MHz, CDCl3):
d = 4.2, 55.1, 79.6, 85.7, 114.0, 116.3, 124.0, 125.0, 129.2,
159.2.
This work has been supported financially by Grant-in-Aid for
Scientific Research from the Ministry of Education, Culture,
Sports, Science and Technology, Japan (MEXT) and Tokuyama
foundation.
1-Methoxy-4-(1-propynyl)benzene (3c): colorless oil. 1H
NMR (500 MHz, CDCl3): d = 2.03 (s, 3 H), 3.78 (s, 3 H),
6.81 (d, J = 8.9 Hz, 2 H), 7.32 (d, J = 8.9 Hz, 2 H). 13C NMR
(125 MHz, CDCl3): d = 4.3, 55.2, 79.4, 84.1, 113.8, 116.1,
132.7, 158.9.
References and Notes
(1) (a) Otera, J. Pure Appl. Chem. 2006, 78, 731. (b) Orita, A.;
Otera, J. Chem. Rev. 2006, 106, 5387.
(2) (a) Sancho, J.; Schrock, R. R. J. Mol. Catal. 1982, 15, 75.
(b) Kaneta, N.; Hirai, T.; Mori, M. Chem. Lett. 1995, 627.
(c) Kaneta, N.; Hikichi, K.; Asaka, S.-I.; Uemura, M.; Mori,
M. Chem. Lett. 1995, 1055. (d) Weis, K.; Michel, A.; Auth,
E.-M.; Bunzu, U. H. F.; Mangel, T.; Müllen, K. Angew.
Chem., Int. Ed. Engl. 1997, 36, 506. (e)Fürstner, A.;Seidel,
G. Angew. Chem. Int. Ed. 1998, 37, 1734. (f) Kloppenburg,
L.; Song, D.; Bunz, U. H. F. J. Am. Chem. Soc. 1998, 120,
7973. (g) Brizius, G.; Pschirer, N. G.; Steffen, W.; Stitzer,
K.; zur Loye, H.-C.; Bunz, U. H. F. J. Am. Chem. Soc. 2000,
122, 12435. (h) For a short review: Bunz, U. H. F.;
Kloppenburg, L. Angew. Chem. Int. Ed. 1999, 38, 478.
(3) (a) Sonogashira, K.; Tohda, Y.; Hagihara, N. Tetrahedron
Lett. 1975, 4467. (b) Tohda, Y.; Sonogashira, K.; Hagihara,
N. Synthesis 1977, 777. (c) Takahashi, S.; Kuroyama, Y.;
Sonogashira, K.; Hagihara, N. Synthesis 1980, 627.
(d) Tomizaki, K.-Y.; Loewe, R. S.; Kirmaier, C.; Schwartz,
J. K.; Retsek, J. L.; Bocian, D. F.; Holten, D. F.; Lindsey, J.
S. J. Org. Chem. 2002, 67, 6519. (e) Bauer, R. E.;
1,4-Dimethoxy-2-(1-propynyl)benzene (3d): white
powder; mp 61–62 °C. 1H NMR (500 MHz, CDCl3): d = 2.12
(s, 3 H), 3.75 (s, 3 H), 3.84 (s, 3 H), 6.77–6.81 (m, 2 H), 6.94
(d, J = 7.5 Hz, 1 H). 13C NMR (125 MHz, CDCl3): d = 4.8,
55.7, 56.3, 75.7, 90.1, 111.6, 113.4, 114.7, 118.3, 153.1,
154.2.
1-Phenylmethyloxy-2-(1-propynyl)benzene (3e):
colorless oil. 1H NMR (500 MHz, CDCl3): d = 2.12 (s, 3 H),
5.18 (s, 2 H), 6.87 (d, J = 8.3 Hz, 1 H), 6.89 (t, J = 7.5 Hz, 1
H), 7.18 (t, J = 8.0 Hz, 1 H), 7.30 (t, J = 7.2 Hz, 1 H), 7.36–
7.40 (m, 3 H), 7.47 (d, J = 7.6 Hz, 2 H). 13C NMR (125 MHz,
CDCl3): d = 4.7, 70.3, 75.8, 90.1, 112.8, 113.9, 120.8, 126.8,
127.6, 128.4, 128.7, 133.1, 159.0.
1-Bromo-2-(1-propynyl)benzene (3f): yellow oil. 1H NMR
(500 MHz, CDCl3): d = 2.11 (s, 3 H), 7.11 (t, J = 7.7 Hz, 1
H), 7.22 (t, J = 8.0 Hz, 1 H), 7.42 (d, J = 7.7 Hz, 1 H), 7.55
(d, J = 8.0 Hz, 1 H). 13C NMR (125 MHz, CDCl3): d = 4.4,
78.4, 90.8, 125.1, 125.8, 126.7, 128.6, 132.1, 133.2.
4-Bromo-1-(1-propynyl)benzene (3g): yellow oil. 1H
NMR (500 MHz, CDCl3): d = 2.02 (s, 3 H), 7.23 (d, J = 8.4
Hz, 2 H), 7.40 (d, J = 8.4 Hz, 2 H). 13C NMR (125 MHz,
CDCl3): d = 4.3, 78.7, 87.1, 121.6, 122.9, 131.4, 132.9.
1-Iodo-2-(1-propynyl)benzene (3h): yellow oil. 1H NMR
(500 MHz, CDCl3): d = 2.11 (s, 3 H), 6.94 (t, J = 8.0 Hz, 1
H), 7.25 (t, J = 7.6 Hz, 1 H), 7.39 (d, J = 7.6 Hz, 1 H), 7.81
(d, J = 8.0 Hz, 1 H). 13C NMR (125 MHz, CDCl3): d = 4.5,
82.0, 90.2, 100.8, 127.7, 128.7, 130.4, 132.5, 138.5.
(1-Propynyl)ferrocene (3j): red powder; mp 79–80 °C. 1H
NMR (500 MHz, CDCl3): d = 1.94 (s, 3 H), 4.13 (t, J = 1.8
Hz, 2 H), 4.19 (s, 5 H), 4.35 (t, J = 1.8 Hz, 2 H). 13C NMR
(125 MHz, CDCl3): d = 4.4, 66.0, 68.0, 69.6, 70.9, 77.2,
81.7.
Enkelmann, V.; Wiesler, U. M.; Berresheim, A. J.; Müllen,
K. Chem. Eur. J. 2002, 8, 3858. (f) Lu, M.; Wei, Y.; Xu, B.;
Cheng, C. F.-C.; Peng, Z.; Powell, D. R. Angew. Chem. Int.
Ed. 2002, 41, 1566. (g) Pappenfus, T. M.; Mann, K. R. Org.
Lett. 2002, 4, 3043. (h) For a most recent review:
Chinchilla, R.; Nájera, C. Chem. Rev. 2007, 107, 874.
(4) (a) Orita, A.; Miyamoto, K.; Nakashima, M.; Ye, F.; Otera,
J. Adv. Synth. Catal. 2004, 346, 767. (b) Orita, A.; Ye, F.;
Babu, G.; Ikemoto, T.; Otera, J. Can. J. Chem. 2005, 83, 716.
(5) (a) Maryanoff, B. E.; Reitz, A. B. Chem. Ber. 1989, 89, 863.
(b) Kolodiazhyl, O. I. Phosphorus Ylides, Chemistry and
Application in Organic Synthesis; Wiley-VCH: Weinheim,
1999.
(6) McMurry, J. E. Chem. Rev. 1989, 89, 1513.
(7) Liu, Y.; Nishiura, M.; Wang, Y.; Hou, Z. J. Am. Chem. Soc.
2006, 128, 5592.
2-Bromo-5-(1-propynyl)thiophene (3k): red oil. 1H NMR
(500 MHz, CDCl3): d = 2.06 (s, 3 H), 6.84 (d, J = 3.7 Hz, 1
H), 6.88 (d, J = 3.9 Hz, 1 H). 13C NMR (125 MHz, CDCl3):
d = 4.7, 72.2, 91.3, 111.4, 125.9, 129.7, 131.2.
1-(Phenylethynyl)-2-(1-propynyl)benzene(3l): yellow oil.
1H NMR (500 MHz, CDCl3): d = 2.15 (s, 3 H), 7.23–7.26 (m,
2 H), 7.33–7.38 (m, 3 H), 7.42–7.44 (m, 1 H), 7.50–7.52 (m,
1 H), 7.54–7.57 (m, 2 H). 13C NMR (125 MHz, CDCl3): d =
4.5, 78.5, 88.5, 90.3, 92.9, 123.3, 125.5, 126.5, 127.2, 127.9,
128.2, 128.3, 131.5, 131.6, 131.1.
(8) Typical Procedure of Preparation for 2-(1-
Propynyl)naphthalene (3i): To a THF solution (15 mL) of
ethyl phenyl sulfone (1, 204.3 mg, 1.2 mmol) was added
BuLi (1.6 M, 0.75 mL, 1.2 mmol) at –78 °C, and the mixture
was stirred for 30 min. A THF solution (2 mL) of 2-naph-
thaldehyde (156.2 mg, 1.0 mmol) was added at –78 °C, and
the mixture was stirred for 30 min. Diethyl chlorophosphate
(207.1 mg, 1.2 mmol) was added at –78 °C, and the mixture
Synlett 2007, No. 12, 1909–1912 © Thieme Stuttgart · New York

1912
D.-L. An et al.
LETTER
1-(Phenylethynyl)-3-(1-propynyl)benzene (3m): colorless
oil. 1H NMR (500 MHz, CDCl3): d = 2.03 (s, 3 H), 7.23 (t,
J = 7.9 Hz, 1 H), 7.31–7.34 (m, 4 H), 7.41 (d, J = 7.6 Hz, 1
H), 7.50–7.52 (m, 2 H), 7.57 (s, 1 H). 13C NMR (125 MHz,
CDCl3): d = 4.3, 78.9, 86.6, 88.6, 89.7, 123.0, 123.3, 124.3,
128.2, 128.3, 130.6, 131.2, 131.6, 134.5.
1-(Phenylethynyl)-4-(1-propynyl)benzene (3n): white
powder; mp 99–101 °C. 1H NMR (500 MHz, CDCl3): d =
2.06 (s, 3 H), 7.32–7.34 (m, 3 H), 7.35 (d, J = 8.6 Hz, 2 H),
7.44 (d, J = 8.2 Hz, 2 H), 7.51–7.53 (m, 2 H). 13C NMR (125
MHz, CDCl3): d = 4.4, 79.5, 87.9, 89.1, 90.7, 122.3, 123.0,
123.9, 128.3, 131.3, 131.4, 131.5.
1,2-Bis[2-(1-propynyl)phenyloxymethyl]benzene (3o):
white powder; mp 99–100 °C. 1H NMR (500 MHz, CDCl3):
d = 2.04 (s, 6 H), 5.33 (s, 4 H), 6.89 (t, J = 7.5 Hz, 2 H), 6.97
(d, J = 8.3 Hz, 2 H), 7.21 (t, J = 7.8 Hz, 2 H), 7.34–7.36 (m,
2 H), 7.38 (d, J = 7.6 Hz, 2 H), 7.61 (s, 2 H). 13C NMR (125
MHz, CDCl3): d = 4.6, 68.7, 75.9, 90.1, 112.4, 113.7, 120.8,
128.0, 128.2, 128.8, 133.4, 134.9, 158.8.
1,3-Bis[2-(1-propynyl)phenyloxymethyl]benzene (3p):
pale yellow oil. 1H NMR (500 MHz, CDCl3): d = 2.10 (s, 6
H), 5.18 (s, 4 H), 6.85 (d, J = 8.3 Hz, 2 H), 6.89 (t, J = 7.5
Hz, 2 H), 7.17 (t, J = 7.9 Hz, 2 H), 7.36–7.42 (m, 5 H), 7.59
(s, 1 H). 13C NMR (125 MHz, CDCl3): d = 4.7, 70.4, 75.8,
90.2, 113.0, 114.0, 120.9, 125.4, 126.2, 128.6, 128.7, 133.5,
137.4, 159.0.
1,4-Bis[2-(1-propynyl)phenyloxymethyl]benzene (3q):
white powder; mp 112–114 °C. 1H NMR (500 MHz,
CDCl3): d = 2.10 (s, 6 H), 5.15 (s, 4 H), 6.84–6.89 (m, 2 H),
7.17 (t, J = 7.8 Hz, 2 H), 7.38 (d, J = 7.6 Hz, 4 H), 7.46 (s, 4
H). 13C NMR (125 MHz, CDCl3): d = 4.7, 70.2, 75.8, 90.1,
112.8, 113.9, 120.8, 127.0, 128.7, 133.5, 136.5, 159.0.
Typical Procedure of Preparation for 2-(4-Phenylbut-3-
en-1-ynyl)naphthalene (4a): To a THF solution (10 mL) of
2-(1-propynyl)naphthalene (83.1 mg, 0.5 mmol) and DMPU
(64.1 mg, 0.5 mmol) was added BuLi (1.6 M, 0.31 mL, 0.5
mmol) at –78 °C, and the mixture was stirred for 30 min. A
THF solution (2 mL) of benzaldehyde (53.1 mg, 0.5 mmol)
was added at –78 °C, and the mixture was stirred for 30 min.
Diethyl chlorophosphate (103.5 mg, 0.6 mmol) was added at
–78 °C, and the mixture was stirred at r.t. for 2 h. t-BuOK
(140.3 mg, 1.25 mmol) was added at –78 °C, and the mixture
was stirred at r.t. for 2 h. After usual workup with EtOAc and
aq NH4Cl solution, the organic layer was evaporated, and the
residue was subjected to column chromatography on silica
gel and recrystallization (from hexane) to afford (E)-2-(4-
phenylbut-3-en-1-ynyl)naphthalene (4a) as a white powder
(59.0 mg, 46%). Recrystallization of the second crop from
hexane gave a 3:5 mixture of E- and Z-isomers (21.1 mg,
17%).
1 H), 7.78–7.82 (m, 3 H), 8.00 (s, 1 H). 13C NMR (125 MHz,
CDCl3): d = 89.3, 92.2, 108.1, 120.7, 126.3, 126.5, 126.6,
127.7, 127.8, 128.0, 128.3, 128.6, 128.7, 131.3, 132.7,
133.0, 136.3, 141.4. ESI–MS: m/z [M+] calcd for C20H14:
254.1; found: 254.8.
(E)-2-[4-(4-Methoxyphenyl)but-3-en-1-ynyl]naph-
thalene (4b): pale yellow powder; mp 145–147 °C (hexane).
1H NMR (500 MHz, CDCl3): d = 3.83 (s, 3 H), 6.29 (d, J =
16.2 Hz, 1 H), 6.89 (d, J = 8.5 Hz, 2 H), 7.05 (d, J = 16.2 Hz,
1 H), 7.40 (d, J = 8.5 Hz, 2 H), 7.47–7.55 (m, 3 H), 7.78–7.82
(m, 3 H), 7.98 (s, 1 H). 13C NMR (125 MHz, CDCl3): d =
55.3, 89.7, 91.4, 105.7, 114.2, 120.9, 126.5, 126.6, 127.6,
127.7, 127.8, 127.9, 128.3, 129.2, 131.1, 132.6, 133.0,
141.0, 160.1. ESI–MS: m/z [M+] calcd for C21H16O: 284.1;
found: 284.8.
(E)-1-(4-Phenylbut-3-en-1-ynyl)-4-phenyl-
ethynylbenzene (4c): white powder; mp 171–173 °C
(hexane). 1H NMR (500 MHz, CDCl3): d = 6.40 (d, J = 16.5
Hz, 1 H), 7.06 (d, J = 16.5 Hz, 1 H), 7.30 (t, J = 7.4 Hz, 1 H),
7.34–7.37 (m, 5 H), 7.44 (d, J = 8.3 Hz, 2 H), 7.45 (d, J = 8.5
Hz, 2 H), 7.51 (d, J = 8.6 Hz, 2 H), 7.53–7.55 (m, 2 H). 13
C
NMR (125 MHz, CDCl3): d = 89.1, 90.8, 91.3, 91.5, 107.9,
122.9, 123.0, 123.2, 126.4, 128.4, 128.5, 128.8, 131.4,
131.5, 131.6, 136.2. ESI–MS: m/z [M+] calcd for C24H16:
304.1; found: 304.8.
(E)-2-[4-(2-Naphthyl)but-3-en-1-ynyl]naphthalene (4d):
yellow powder; mp 157–158 °C (hexane). 1H NMR (300
MHz, CDCl3): d = 6.56 (d, J = 16.3 Hz, 1 H), 7.26 (d, J =
16.3 Hz, 1 H), 7.47–7.52 (m, 4 H), 7.55 (d, J = 8.6 Hz, 1 H),
7.65 (d, J = 8.6 Hz, 1 H), 7.80–7.86 (m, 7 H), 8.02 (s, 1 H).
13C NMR (125 MHz, CDCl3): d = 89.5, 92.6, 108.4, 120.7,
122.7, 126.4, 126.5, 126.6, 126.7, 127.0, 127.7, 127.8,
127.9, 128.0, 128.2, 128.3, 128.5, 131.3, 132.8, 133.0,
133.5, 133.8, 141.5. ESI–MS: m/z [M+] calcd for C24H16:
304.1; found: 304.8.
(E)-1-(Phenylethynyl)-4-{4-[4-(phenyl-ethynyl)phen-
yl]but-3-en-1-ynyl}benzene (4e): yellow powder; mp 263–
266 °C (CH2Cl2). 1H NMR (500 MHz, CDCl3): d = 6.43 (d,
J = 16.4 Hz, 1 H), 7.04 (d, J = 16.4 Hz, 1 H), 7.35–7.37 (m,
7 H), 7.43 (d, J = 8.3 Hz, 2 H), 7.45 (d, J = 8.6 Hz, 2 H), 7.50
(d, J = 8.3 Hz, 2 H), 7.51 (d, J = 8.3 Hz, 2 H), 7.53–7.55 (m,
3 H). ESI–MS: m/z [M+] calcd for C32H20: 404.2; found:
404.9. 13C NMR could not be measured because of poor
solubility.
(E)-1-(4-Methoxyphenylethynyl)-3-(4-phenylbut-3-en-1-
ynyl)benzene (4f): mp 104–106 °C (hexane). 1H NMR (300
MHz, CDCl3): d = 3.84 (s, 3 H), 6.39 (d, J = 16.2 Hz, 1 H),
6.89 (d, J = 8.8 Hz, 2 H), 7.06 (d, J = 16.2 Hz, 1 H), 7.28 (d,
J = 8.0 Hz, 1 H), 7.30 (d, J = 7.7 Hz, 1 H), 7.35 (d, J = 8.0
Hz, 1 H), 7.37 (d, J = 7.6 Hz, 1 H), 7.40–7.46 (m, 4 H), 7.48
(d, J = 8.9 Hz, 2 H), 7.63 (s, 1 H). 13C NMR (125 MHz,
CDCl3): d = 55.3, 87.3, 89.4, 90.0, 90.9, 107.9, 114.0, 123.7,
123.9, 126.3, 128.3, 128.4, 128.7, 128.8, 130.8, 131.0,
133.1, 134.3, 136.2, 141.6, 159.7. ESI–MS: m/z [M+] calcd
for C25H18O: 334.1; found: 334.9.
(E)-2-(4-Phenylbut-3-en-1-ynyl)naphthalene (4a): white
powder; mp 135–136 °C (hexane). 1H NMR (500 MHz,
CDCl3): d = 6.44 (d, J = 16.2 Hz, 1 H), 7.09 (d, J = 16.2 Hz,
1 H), 7.30 (t, J = 7.4 Hz, 1 H), 7.35 (d, J = 7.6 Hz, 1 H), 7.36
(d, J = 8.6 Hz, 1 H), 7.44–7.50 (m, 4 H), 7.53 (d, J = 8.2 Hz,
Synlett 2007, No. 12, 1909–1912 © Thieme Stuttgart · New York

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