A novel access to disubstituted acetylenes

Article abstract of DOI:10.1021/jo0201575

Reactions of organometallic reagents with 1-(substituted ethynyl)-1H-1,2,3-benzotriazoles 5 derived from a variety of benzotriazolylmethyl ketones 3 afforded disubstituted acetylenes in synthetically useful yields.

Full text of DOI:10.1021/jo0201575

SCHEME 1
A Novel Access to Disu bstitu ted Acetylen es
Alan R. Katritzky,* Ashraf A. A. Abdel-Fattah, and
Mingyi Wang
Center for Heterocyclic Compounds,
Department of Chemistry, University of Florida,
Gainesville, Florida 32611-7200
katritzky@chem.ufl.edu
Received March 8, 2002
SCHEME 2a
Abstr a ct: Reactions of organometallic reagents with 1-(sub-
stituted ethynyl)-1H-1,2,3-benzotriazoles 5 derived from a
variety of benzotriazolylmethyl ketones 3 afforded disubsti-
tuted acetylenes in synthetically useful yields.
Over the years, continuous attention has been devoted
to acetylene chemistry. The acetylenic bond plays a
significant role in organic reactions and in applications
ranging from material science to biochemistry.1a,b Impor-
tant methods for the synthesis of acetylenes include the
following (Scheme 1): (i) from terminal acetylenes by
alkylation of carbanionic intermediates,2a,b or by transi-
tion metal-promoted cross-couplings with alkyl or aryl
halides;3a-e (ii) reactions of halogenoacetylenes with
Grignards, organolithium reagents,4a,b or organostan-
nanes;5a,b (iii) reactions of alkynylstannanes with iodo-
nium salts;6 and (iv) reaction of â-keto-ester with hy-
droxylamine to obtain first the corresponding isoxazol-
5-one followed by nitrosation.7
a
For designation of R, R1 in 6 and R, Het in 8 see Table 1.
In method ii, the degree of success depends on a
number of factors, including the nature of the halide, the
solvent, and the organometallic reagent. In the absence
of catalysis by other metals, reactions with Grignard
reagents are limited to alkylmagnesium halides; with
both alkenyl and aryl Grignards, metal-halogen inter-
change occurs. In the reaction with organolithium re-
agents, the usual reaction is halogen-metal exchange
with formation of an alkynyllithium. Benzotriazole is a
good leaving group, which can be used in place of a
halogen in many reactions.8 We now disclose the first
examples of the displacement of the benzotriazole moiety
from 1-arylethynyl-1H-1,2,3-benzotriazoles by organo-
metallic reagents, which provides a new synthetic path-
way from acid chlorides to disubstituted acetylenes:
RCOCl + BtCH2SiMe3 f RCOCH2Bt f RCtCBt f
RCtCR1 when R1 can be alkyl, allyl, aryl, or heteroaryl.
On e-P ot Syn th esis of 1-(Su bstitu ted eth yn yl)-1H-
1, 2,3-ben zotr ia zoles 5. Direct alkynylation is conve-
nient for the preparation of many alkynyl derivatives.
Kitamura’s group prepared 1-(arylalkynyl)benzotriazoles
by way of reaction with arylethynyl(phenyl)iodonium
tosylates in yields of 55-62%,9a,b but failed to obtain
N-(alkylethynyl)benzotriazoles. Recently,10 1-(substituted
ethynyl)benzotriazoles 5 were synthesized in yields of
90-98% by treatment of (E)-2-(1H-1,2,3-benzotriazole-
1-yl)-1-(substituted ethenyl)trifluoromethane-sulfonates
(4) with 2 N NaOH. This procedure has now been
simplified to provide a one-pot synthesis of 5 (Scheme
2).
(1) (a) Modern Acetylene Chemistry; Stang, P. J ., Diederich, F., Eds.;
VCH: Weinheim, Germany, 1995. (b) Furber, M. Comprehensive
Organic Functional Group Transformations; Katritzky, A. R., Meth-
Cohn, O., Rees, C. W., Eds.; Pergamon: Oxford, UK, 1995; Vol. 1,
Chapter 1.21, p 997.
(2) (a) Henrick, C. A. Tetrahedron 1977, 33, 1845. (b) Cossy, J .; Pete,
J . P. Tetrahedron Lett. 1986, 27, 573.
(3) (a) Singh, R.; J ust, G. J . Org. Chem. 1989, 54, 4453. (b) Grushin,
V. V.; Alper, H. J . Org. Chem. 1992, 57, 2188. (c) Alami, M.; Ferri, F.;
Linstrumelle, G. Tetrahedron Lett. 1993, 34, 6403. (d) Nguefack, J .-
F.; Bolitt, V.; Sinou, D. Tetrahedron Lett. 1996, 37, 5527. (e) Iyer, S.;
Ramesh, C.; Ramani, A. Tetrahedron Lett. 1997, 38, 8533.
(4) (a) Normant, J . Bull. Soc. Chim. Fr. 1963, 876. (b) Normant, J .
Bull. Soc. Chim. Fr. 1963, 1888.
Treatment of N-acylmethylbenzotriazoles (3a -f) with
triflic anhydride (Tf2O) in the presence of 2,6-lutidine in
(5) (a) Ma, Y.; Huang, X. Synth. Commun. 1997, 27, 3441. (b) Kang,
S.-K.; Kim, W.-Y.; J iao, X. Synthesis 1998, 1252.
(6) Kang, S.-K.; Lee, H.-W.; J ang, S.-B.; Kim, T.-H.; Kim, J .-S. Synth.
Commun. 1996, 26, 4311.
(7) Boivin, J .; Elkaim, L.; Ferro, P. G.; Zard, S. Z. Tetrahedron Lett.
1991, 32, 5321.
(8) Katritzky, A. R.; Lan, X.; Yang, J . Z.; Denisko, O. V. Chem. Rev.
1998, 98, 409.
(9) (a) Kitamura, T.; Tashi, N.; Tsuda, K.; Fujiwara, Y. Tetrahedron
Lett. 1998, 39, 3787. (b) Kitamura, T.; Tashi, N.; Tsuda, K.; Chen, H.;
Fujiwara, Y. Heterocycles 2000, 52, 303.
(10) Katritzky, A. R.; Zhang, S.; Fang, Y. Org. Lett. 2000, 2, 3789.
10.1021/jo0201575 CCC: $22.00 © 2002 American Chemical Society
Published on Web 09/21/2002
7526
J . Org. Chem. 2002, 67, 7526-7529

TABLE 1. Syn th esis of Acetylen es 6 a n d 8 via
Alk yn yla tion of Or ga n om eta llic Rea gen ts w ith
1-(Ar yleth yn yl)ben zotr ia zoles 5
from 4% to 67% and afforded previously unreported
derivatives of benzothiophene 8c,d .
This approach for the synthesis of disubstituted acety-
lenes is advantageous compared with the closest litera-
ture analogy, which is the reaction of halogenoacetylenes
with Grignard or organolithium reagents4a,b (Scheme 1,
ii). It utilitizes commercially available starting materials
(e.g. RCO2H and heteroaromatic in the case of heteroaro-
matic acetylenes), and requires no transition metal
catalyst. Thus, 1-(arylethynyl)benzotriazoles constitute
superior alkynylating agents for organometallic reagents.
In summary, we have developed a convenient method
for the preparation of alkynylbenzotriazoles 5 starting
from N-acylmethylbenzotriazoles 3. These alkynylben-
zotriazoles have interesting synthetic potential, and their
reaction with organometallic reagents provides a new,
efficient, and broadly applicable synthetic methodology
for the synthesis of disubstituted acetylenes.
entry
R
R1/Het
yield (%)
6a
6b
6c
6d
6e
6f
6g
6h
6i
8a
8b
8c
8d
8e
C6H5
C6H5
CH3(CH2)3CH2
CH2dCH-CH2
CH3(CH2)3CH2
CH2dCH-CH2
CH2dCH-CH2
C6H5
C6H5
4-ClC6H4
C6H5
thiophen-2-yl
thiophen-2-yl
benzothiophen-2-yl
benzothiophen-2-yl
benzofuran-2-yl
76
79
83
75
81
51
63
70
68
58
65
70
62
67
2-naphthyl
2-naphthyl
4-BrC6H4
4-CH3C6H4
2-naphthyl
2-naphthyl
4-BrC6H4
C6H5
4-BrC6H4
C6H5
4-BrC6H4
C6H5
CH2Cl2 at 0-20 °C for 2-12 h affords the corresponding
enol triflates 4a -f. Removal of the solvent and treatment
with 2 N NaOH in THF at 20 °C gave the 1-(substituted
ethynyl)-1H-1,2,3-benzotriazoles 5a -f in 70-90% yields.
The 13C NMR spectra of alkynylbenzotriazoles 5a -f
revealed two characteristic signals of the acetylenic bond
at 66.9-76.1 and 76.3-80.3 ppm.
Rea ction s of Alk yn ylben zotr ia zoles 5 w ith Or ga -
n om eta llic Rea gen ts. Treatment of 1-arylethynyl-1H-
1,2,3-benzotriazoles 5a -d with Grignard reagents in dry
toluene at -45 to 20 °C afforded acetylenes 6a -i (Scheme
2, Table 1). This synthetic route provided the known
compounds 6a ,b,f,g in yields comparable with those
reported in the literature.3c,6,7,11 The yields of previously
unreported acetylenes 6c-e,h ,i were 68-83%. The NMR
spectra of the displacement products 6a -i clearly showed
the disappearance of the characteristic benzotriazolyl
signals and the data for the known compounds are
consistent with those reported in the literature. The
acetylenic bond signals in 13C NMR spectra were shifted
downfield as compared to those of their precursors due
to the loss of the benzotriazolyl group.
Exp er im en ta l Section
Gen er a l. Melting points were determined on a hot stage
apparatus and are uncorrected. NMR spectra were recorded in
CDCl3 with tetramethylsilane as internal standard for 1H (300
MHz) or solvent as the internal standard for 13C (75 MHz).
Microanalyses were performed on a Carlo Erba 1106 elemental
analyzer. Anhydrous solvents were obtained by distillation
immediately prior to use, from calcium hydride (dichloromethane)
or from sodium (toluene). Column chromatography was con-
ducted with silica gel 200-425 mesh. BtCH2TMS (1) and
N-(acylmethyl)benzotriazoles 3a -f were prepared according to
literature procedures.14
Gen er a l P r oced u r e for th e P r ep a r a tion of 1-(Su bstitu t-
ed eth yn yl)ben zotr ia zoles 5a -f. Triflic anhydride (15 mmol)
was added dropwise to a mixture of N-(acylmethyl)benzotriazoles
1 (10 mmol) and 2,6-lutidine (15 mmol) in dry dichloromethane
(50 mL) at 0-20 °C for 2-12 h. The mixture was concentrated
under reduced pressure, and the residue was treated with 2 N
NaOH (10 mL) in THF (30 mL) at 20 °C for 1 h. The mixture
was then diluted with ethyl acetate, washed with water, and
dried over MgSO4. The solvent was removed in vacuo, and the
residue was purified by column chromatography with CH2Cl2
as an eluent.
The reaction of 1-(alkylethynyl)benzotriazoles 5e,f with
Grignard reagents under the same reaction conditions
provided only the cis addition products 7a -c in 76-91%
yields, instead of the expected products of type 6 (Scheme
2). No trans isomers were detected in the NMR spectra
of the crude 7a -c. This cis configuration of 7 was
established by NOE: for example, irradiation of the
vinylic proton of 7b at 7.21 ppm showed NOE effects on
the methyl group protons at 2.36 ppm. Elemental analy-
ses and NMR spectral data supported the structure of
7a -c. In 13C NMR spectra, the newly formed olefinic
bond in compounds 7a -c was exhibited at 116.8-118.7
and 138.8-143.0 ppm.
1-(2-P h en yleth yn yl)-1H-1,2,3-ben zotr ia zole (5a ). Color-
less crystals (76%), mp 78-79 °C (lit.10 mp 78-78.5 °C). 1H NMR
δ 7.42-7.50 (m, 4H), 7.62-7.67 (m, 3H), 7.75 (d, J ) 8.2 Hz,
1H), 8.13 (d, J ) 8.4 Hz, 1H). 13C NMR δ 75.8, 79.8, 110.1, 120.5,
120.6, 125.3, 128.6, 129.4, 129.5, 131.8, 134.2, 143.9.
1-[2-(4-Meth ylph en yl)eth yn yl]-1H-1,2,3-ben zotr iazole (5b).
1
Solid (70%), mp 86-88 °C (lit.10 mp 84-85 °C). H NMR δ 2.39
(s, 3H), 7.22 (d, J ) 7.7 Hz, 2H), 7.43-7.54 (m, 3H), 7.62 (t, J )
7.6 Hz, 1H), 7.73 (d, J ) 8.1 Hz, 1H), 8.12 (d, J ) 8.2 Hz, 1H).
13C NMR δ 21.5, 75.2, 79.9, 110.1, 117.5, 120.5, 125.2, 129.2,
129.3, 131.8, 134.2, 139.8, 143.9.
1-[2-(2-Naph th yl)eth yn yl]-1H-1,2,3-ben zotr iazole (5c). Pale
yellow solid (88%), mp 146-148 °C. 1H NMR δ 7.48-7.56 (m,
3H), 7.64-7.67 (m, 2H), 7.79 (d, J ) 8.2 Hz, 1H), 7.84-7.89 (m,
3H), 8.13-8.16 (m, 2H). 13C NMR δ 76.0, 80.3, 110.2, 117.9,
120.6, 125.3, 126.9, 127.3, 127.8, 127.9, 128.0, 128.4, 129.4, 132.2,
132.8, 133.3, 134.3, 144.0. Anal. Calcd for C18H11N3: C, 80.28;
H, 4.12; N, 15.60. Found: C, 80.06; H, 3.97; N, 15.51.
1-[2-(4-Br om oph en yl)eth yn yl]-1H-1,2,3-ben zotr iazole (5d).
Pale yellow plates (85%), mp 142-144 °C. 1H NMR δ 7.47-7.59
(m, 5H), 7.66 (t, J ) 11 Hz, 1H), 7.75 (d, J ) 8.2 Hz, 1H), 8.15
(d, J ) 8.2 Hz, 1H). 13C NMR δ 76.1, 78.9, 110.1, 119.7, 120.7,
124.0, 125.4, 129.5, 132.0, 133.2, 134.2, 143.9. Anal. Calcd for
Heterocyclic lithio-derivatives (generated by lithiation
of the corresponding heterocycle12a,b) reacted with inter-
mediates 5a ,d to give 1-aryl-2-heterylacetylenes 8a -e in
58-70% yields (Scheme 2, Table 1). This synthetic route
improved the previously reported yield13 of compound 8e
(11) de la Rosa, M. A.; Velarde, E.; Guzman, A. Synth. Commun.
1990, 20, 2059.
(12) (a) Strekowski, L.; Watson, R. J . Org. Chem. 1986, 51, 3226.
(b) Yokoyama, M.; Akiba, T.; Ochiai, Y.; Momotake, A.; Togo, H. J .
Org. Chem. 1996, 61, 6079.
C
14H8BrN3: C, 56.40; H, 2.70; N, 14.09. Found: C, 56.42; H,
2.67; N, 13.84.
(13) Tsuge, O.; Ueno, K.; Oe, K. Chem. Lett. 1981, 135.
(14) Katritzky, A. R.; Lam, J . N. Heteroatom Chem. 1990, 1, 21.
J . Org. Chem, Vol. 67, No. 21, 2002 7527

1-(1-P r op yn yl)-1H-1,2,3-ben zotr ia zole (5e). Colorless solid
(82%), mp 37-38 °C. 1H NMR δ 2.22 (s, 3H), 7.41 (t, J ) 7.6 Hz,
1H), 7.57 (t, J ) 7.5 Hz, 1H), 7.64 (d, J ) 8.2 Hz, 1H), 8.07 (d,
J ) 8.2 Hz, 1H). 13C NMR δ 3.6, 66.9, 76.3, 110.0, 120.3, 124.9,
129.0, 134.3, 143.7. Anal. Calcd for C9H7N3: C, 68.77; H, 4.49;
N, 26.73. Found: C, 68.49; H, 4.85; N, 26.67.
1-Br om o-4-(2-ph en yleth yn yl)ben zen e (6i). Colorless plates
(68%), mp 82-83 °C. 1H NMR δ 7.33-7.40 (m, 5H), 7.47-7.54
(m, 4H). 13C NMR δ 88.3, 90.5, 122.2, 122.5, 122.9, 128.4, 128.5,
131.6, 131.6, 133.0. Anal. Calcd for C14H9Br: C, 65.40; H, 3.53.
Found: C, 65.07; H, 3.34.
Gen er a l P r oced u r e for th e P r ep a r a tion of 7a -c. To a
solution of 1-(alkylethynyl)benzotriazole (1 mmol) in dry toluene
(10 mL) was added Grignard reagent (2 mmol, 1.0 M in THF)
at -45 °C. The resulting mixture was stirred at this temperature
for 2 h and then allowed to warm to 20 °C. After quenching with
water and extraction with ethyl acetate (3 × 10 mL), the
combined organic extracts were dried over MgSO4. The solvent
was removed in vacuo and the resulting oil was purified by
column chromatography (eluent: EtOAc-hexanes 1:4) to give
the pure product.
1-(2-Meth yl-1-h ep ten yl)-1H-1,2,3-ben zotr ia zole (7a ). Liq-
uid (91%). 1H NMR δ 0.79 (t, J ) 6.9 Hz, 3H), 1.12-1.19 (m,
4H), 1.40-1.48 (m, 2H), 2.03 (s, 3H), 2.10 (t, J ) 4.7 Hz, 2H),
6.80 (s, 1H), 7.36-7.53 (m, 3H), 8.07 (d, J ) 8.2 Hz, 1H). 13C
NMR δ 13.8, 20.4, 22.2, 27.0, 31.4, 31.7, 109.8, 116.8, 119.9,
123.9, 127.5, 133.4, 143.0, 145.2. Anal. Calcd for C14H19N3: N,
18.32. Found: N, 18.03.
1-[2-(4-Met h ylp h en yl)-1-p r op en yl]-1H -1,2,3-b en zot r ia -
zole (7b). Colorless plates (76%), mp 127-129 °C. 1H NMR δ
2.17 (s, 3H), 2.36 (s, 3H), 6.89 (s, 4H), 7.00-7.03 (m, 1H), 7.20-
7.26 (m, 3H), 7.95-7.98 (m, 1H). 13C NMR δ 21.0, 22.4, 110.4,
117.9, 119.5, 123.6, 127.0, 127.2, 129.1, 132.4, 134.6, 138.0, 138.8,
145.3. Anal. Calcd for C16H15N3: N, 16.85. Found: 16.81.
1-[4-Meth yl-2-(4-m eth ylph en yl)-1-pen ten yl]-1H-1,2,3-ben -
zotr ia zole (7c). Colorless plates (72%), mp 90-91 °C. 1H NMR
δ 0.98 (d, J ) 6.6 Hz, 6H), 1.64-1.73 (m, 1H), 2.18 (s, 3H), 2.57
(d, J ) 7.1 Hz, 2H), 6.90 (s, 4H), 6.99-7.02 (m, 1H), 7.17-7.26
(m, 3H), 7.93-7.96 (m, 1H). 13C NMR δ 21.1, 22.2, 26.1, 45.3,
110.4, 118.7, 119.5, 123.6, 127.1, 127.4, 129.1, 132.5, 133.6, 137.8,
142.7, 145.2. Anal. Calcd for C19H21N3: N, 14.42. Found: N,
14.49.
Gen er a l P r oced u r e for th e P r ep a r a tion of Heter ocyclic
Acetylen es 8a -e. To a solution of aromatic heterocycle (1
mmol) in THF (5 mL) was added n-butyllithium (1.2 equiv, 1.56
M hexane solution) dropwise at 0 °C. The solution was allowed
to rise to room temperature and stirred for 1 h. This solution
was maintained at -78 °C while a solution of 5 (1 mmol) in THF
(15 mL) was added slowly with stirring during 10 min. The
reaction mixture was stirred for 12 h while the temperature was
allowed to rise to 20 °C. After quenching with water (5 mL) and
extraction with EtOAc (2 × 20 mL), the combined organic
extracts were dried over MgSO4 and filtered and the solvent was
removed in vacuo. The resulting oil was subjected to column
chromatography (eluent: hexanes) to give the pure product.
2-(2-P h en yleth yn yl)th iop h en e (8a ). Colorless plates (58%),
mp 49-51 °C, (lit.17 mp 51-52 °C). 1H NMR δ 6.99-7.01 (m,
1H), 7.27-7.34 (m, 5H), 7.50-7.53 (m, 2H). 13C NMR δ 82.6,
93.0, 122.9, 123.3, 127.1, 127.2, 128.4, 128.4, 131.4, 131.9.
2-[2-(4-Br om op h en yl)eth yn yl]th iop h en e (8b). Colorless
plates (65%), mp 89-91 °C. 1H NMR δ 7.00-7.16 (m, 1H), 7.28-
7.32 (m, 2H), 7.35-7.38 (m, 2H), 7.48 (d, J ) 8.5 Hz, 1H). 13C
NMR δ 83.8, 91.9, 121.9, 122.6, 122.9, 127.2, 127.6, 131.6, 131.7,
132.1, 132.8. Anal. Calcd for C12H7BrS: C, 54.77; H, 2.68.
Found: C, 55.16; H, 2.37.
1-(4-Meth yl-1-p en tyn yl)-1H-1,2,3-ben zotr ia zole (5f). Pale
1
yellow oil (90%). H NMR δ 1.12 (d, J ) 6.6 Hz, 6H), 1.98-2.07
(m, 1H), 2.50 (d, J ) 6.5 Hz, 2H), 7.44 (t, J ) 7.5 Hz, 1H), 7.57-
7.67 (m, 2H), 8.09 (d, J ) 8.2 Hz, 1H). 13C NMR δ 22.0, 27.7,
27.9, 68.7, 79.5, 110.0, 120.3, 125.0, 129.0, 134.4, 143.7. Anal.
Calcd for C12H13N3: C, 72.33; H, 6.58; N, 21.09. Found: C, 72.01;
H, 6.89; N, 21.19.
Gen er a l P r oced u r e for th e P r ep a r a tion of Acetylen es
6a -i. To a solution of 1-arylethynyl-1H-1,2,3-benzotriazole (1
mmol) in dry toluene (10 mL) was added Grignard reagent (2
equiv, 1.0 M THF solution) dropwise at -45 °C. The resulting
mixture was stirred at this temperature for 2 h and then allowed
to warm to 20 °C. After quenching with water and extraction
with ethyl acetate (3 × 10 mL), the combined organic extracts
were dried over MgSO4. The solvent was removed in vacuo and
the resulting oil was purified by column chromatography (elu-
ent: hexanes) to give the pure product.
1-P h en yl-1-h ep tyn e (6a ).3c Colorless liquid (76%). 1H NMR
δ 0.92 (t, J ) 6.9 Hz, 3H), 1.26-1.46 (m, 4H), 1.58-1.63 (m,
2H), 2.39 (t, J ) 7.1 Hz, 2H), 7.25-7.27 (m, 3H), 7.38-7.39 (m,
2H). 13C NMR δ 14.0, 19.4, 22.2, 28.5, 31.1, 80.5, 90.5, 124.1,
127.4, 128.1, 131.5. Anal. Calcd for C13H16: C, 90.64; H, 9.36.
Found: C, 90.45; H, 9.74.
1-(4-P en ten -1-yn yl)ben zen e (6b). Colorless liquid (79%)
(lit.15 bp 60 °C/0.3 mm). 1H NMR δ 3.25 (dt, J ) 5.2, 1.9 Hz,
2H), 5.20 (dq, J ) 9.9, 1.8 Hz, 1H), 5.47 (dq, J ) 17.0, 1.8 Hz,
1H), 5.87-6.00 (m, 1H), 7.43-7.49 (m, 2H), 7.74-7.81 (m, 2H),
7.94 (s, 1H). 13C NMR δ 23.7, 82.9, 86.5, 116.2, 123.7, 127.7,
128.2, 131.6, 132.4.
2-(1-Hep tyn yl)n a p h th a len e (6c). Colorless liquid (83%). 1H
NMR δ 0.93 (t, J ) 7.1 Hz, 3H), 1.26-1.46 (m, 4H), 1.58-1.63
(m, 2H), 2.39 (t, J ) 7.1 Hz, 2H), 7.25-7.27 (m, 3H), 7.38-7.39
(m, 2H). 13C NMR δ 14.0, 19.4, 22.2, 28.5, 31.1, 80.5, 90.5, 124.1,
127.4, 128.1, 131.5. Anal. Calcd for C13H16: C, 90.64; H, 9.36.
Found: C, 90.45; H, 9.74.
2-(4-P en ten -1-yn yl)n aph th alen e (6d). Colorless liquid (75%).
1H NMR δ 3.20 (dt, J ) 5.3, 1.7 Hz, 2H), 5.17 (dq, J ) 10.0, 1.7
Hz, 1H), 5.41 (dq, J ) 17.0, 1.7 Hz, 1H), 5.85-5.97 (m, 1H),
7.26-7.31 (m, 5H), 7.41-7.44 (m, 2H). 13C NMR δ 23.8, 83.2,
86.3, 116.3, 121.0, 126.3, 126.4, 127.6, 127.7, 127.8, 128.6, 131.2,
132.4, 132.6, 133.0. HRMS calcd for C15H12: 192.2603. Found:
192.0955.
1-Br om o-4-(4-p en ten -1-yn yl)ben zen e (6e). Colorless liquid
(81%). 1H NMR δ 3.18 (dt, J ) 5.2, 1.8 Hz, 2H), 5.17 (dq, J )
9.9, 1.8 Hz, 1H), 5.38 (dq, J ) 16.9, 1.9 Hz, 1H), 5.82-5.95 (m,
1H), 7.27 (d, J ) 8.4 Hz, 2H), 7.42 (d, J ) 8.2 Hz, 2H). 13C NMR
δ 23.7, 81.8, 87.9, 116.4, 121.9, 122.6, 131.4, 132.1, 133.0. HRMS
calcd for C11H9Br: 221.0965. Found: 221.0917.
1-Meth yl-4-(2-p h en yleth yn yl)ben zen e (6f). Colorless solid
(51%), mp 67-69 °C, (lit.16 mp 59-61 °C). 1H NMR δ 2.36 (s,
3H), 7.15 (d, J ) 8.0 Hz, 2H), 7.32-7.35 (m, 3H), 7.43 (d, J )
8.0 Hz, 2H), 7.51-7.53 (m, 2H). 13C NMR δ 21.5, 88.7, 89.5,
120.2, 123.5, 128.0, 128.3, 129.1, 131.4, 131.5, 138.4.
2-(2-P h en yleth yn yl)n aph th alen e (6g). Colorless solid (63%),
mp 110-112 °C, (lit.11 mp 112-113 °C). 1H NMR δ 7.34-7.36
(m, 3H), 7.46-7.49 (m, 2H), 7.56-7.59 (m, 3H), 7.78-7.81 (m,
3H), 8.05 (s, 1H). 13C NMR δ 89.7, 89.8, 120.6, 123.3, 126.5,
126.6, 127.8, 128.0, 128.3, 128.3, 128.4, 131.4, 131.7, 132.8, 133.0.
2-[2-(4-Ch lor op h en yl)eth yn yl]n a p h th a len e (6h ). Color-
less plates (70%), mp 122-123 °C.1H NMR δ 7.34 (d, J ) 8.4
Hz, 2H), 7.48-7.57 (m, 5H), 7.79-7.82 (m, 3H), 8.04 (s, 1H).
13C NMR δ 88.6, 90.7, 120.2, 121.8, 126.6, 126.8, 127.7, 127.8,
128.1, 128.3, 128.7, 131.5, 132.8, 132.9, 133.0, 134.3. Anal. Calcd
for C18H11Cl: C, 82.29; H, 4.22. Found: C, 82.12; H, 4.44.
2-(2-P h en yleth yn yl)-1-ben zoth ioph en e (8c). Colorless solid
(70%), mp 115-117 °C. 1H NMR δ 7.24-7.38 (m, 5H), 7.50 (s,
1H), 7.54-7.57 (m, 2H), 7.74-7.79 (m, 2H). 13C NMR 82.9, 94.8,
122.0, 122.5, 123.2, 123.8, 124.7, 125.4, 128.4, 128.7, 128.8, 131.6,
139.1, 140.3. Anal. Calcd for C16H10S: C, 82.01; H, 4.30. Found:
C, 81.97; H, 4.30.
2-[2-(4-Br om op h en ylet h yn yl)]-1-b en zot h iop h en e (8d ).
1
Pale yellow solid (62%), mp 189-191 °C. H NMR δ 7.36-7.43
(m, 4H), 7.50-7.52 (d, J ) 6.5 Hz, 3H), 7.78-7.79 (m, 2H). 13C
NMR 83.9, 93.5, 121.3, 121.8, 122.6, 122.9, 123.7, 124.6, 125.4,
128.8, 131.5, 132.8, 138.8, 140.1. HRMS calcd for C16H9BrS:
311.9608. Found: 311.9581.
(15) Klein, J .; Brenner, S. Tetrahedron 1970, 26, 5807.
(16) Mouries, V.; Waschbusch, R.; Carran, J .; Savignac, P. Synthesis
1997, 271.
(17) Rossi, R.; Carpita, A.; Lezzi, A. Tetrahedron 1984, 40, 2773.
7528 J . Org. Chem., Vol. 67, No. 21, 2002

2-(2-P h en yleth yn yl)-1-ben zofu r a n (8e). Colorless plates
(67%), mp 87-89 °C (lit.13 mp 88-90 °C). 1H NMR δ 7.00 (s,
1H), 7.25 (t, J ) 7.4 Hz, 1H), 7.31-7.38 (m, 4H), 7.48 (d, J )
8.2 Hz, 1H), 7.57 (d, J ) 5.1 Hz, 3H). 13C NMR δ 79.6, 95.0,
111.2, 111.6, 121.2, 121.8, 123.3, 125.6, 127.7, 128.5, 129.1, 131.6,
138.7, 154.9.
Ack n ow led gm en t. The authors gratefully acknowl-
edge Dr. S. Zhang, and Dr. N. Akhmedov for their
generous help.
J O0201575
J . Org. Chem, Vol. 67, No. 21, 2002 7529