Synthesis of pentafluorophenyl- and pyridinyl-3 allenes

Article abstract of DOI:10.1002/jccs.200700017

The allenes 1,2,3,4,5-pentafluoro-6-(3-phenylpropa-1,2-dienyl)benzene 4, 3-(3-phenylpropa-1,2-dienyl)pyridine 11 and 3-(3-(pyridine-3-yl)propa-1,2- dienyl)pyridine 17 and the acetylenes 5, 12 and 16 were obtained by reduction of the corresponding propargy

Full text of DOI:10.1002/jccs.200700017

Journal of the Chinese Chemical Society, 2007, 54, 103-108
103
Synthesis of Pentafluorophenyl- and Pyridinyl-3 Allenes
Ramazan Erenler†* and Jean-François Biellmann*
Institute of Chemistry, Academia Sinica, Nankang 115, Taipei, Taiwan, R.O.C.
The allenes 1,2,3,4,5-pentafluoro-6-(3-phenylpropa-1,2-dienyl)benzene 4, 3-(3-phenylpropa-1,2-
dienyl)pyridine 11 and 3-(3-(pyridine-3-yl)propa-1,2-dienyl)pyridine 17 and the acetylenes 5, 12 and 16
were obtained by reduction of the corresponding propargylic acetates 3, 10 and 15 by Samarium(II) iodide
in the presence of Pd(0). Base-promoted isomerisation of acetylene 12 provided allene 11 in a yield of
80%. 1-(Pentafluorophenyl)-3-phenylprop-2-yn-1-ol 2 was prepared from phenylacetylene and penta-
fluorobenzaldehyde. The condensation of nicotinaldehyde with trimethylsilylacetylene gave the 3-(tri-
methylsilyl)-1-(pyridine-3-yl)prop-2-yn-1-ol 7. The removal of the silyl group of 7 to acetylene 8 was
done in basic conditions. The Pd catalysed condensation of the acetylene 8 with iodobenzene gave
3-phenyl-1-(pyridine-3-yl)prop-2-yn-1-ol 9. The Pd catalysed condensation of 8 with 3-bromopyridine
gave the 1,3-dipyridin-3-yl-prop-2-yn-1-ol 14. The propargylic alcohols 2, 9 and 14 were converted to the
acetates 3, 10 and 15 with acetic anhydride-pyridine.
Key words: Isomerisation reaction; Heterocyclic allene; Pyridinyl allene; Tetrafluorophenyl
allene; Samarium diiodide.
INTRODUCTION
Allenes present in some natural products is an inter-
padienyl)isoxazole is described as polymerizing in the
solid state.7
Herein we report the synthesis of some novel allenes:
1,2,3,4,5-pentafluoro-6-(3-phenylpropa-1,2-dienyl)ben-
zene 4, 3-(3-phenylpropa-1,2-dienyl)pyridine 11 and 3-
(3-(pyridine-3-yl)propa-1,2-dienyl)pyridine 17.
esting function whose reactivity is useful in synthesis. The
activatation of allenes in biological reactions may lead to
inhibition. The versatility of the allene acting as nucleo-
phile as well as electrophile makes the preparation of some
allenes a difficult task, for instance heterocyclic allenes
whose number are limited. Indeed the presence of an elec-
tron attracting ring increases the reactivity of the allene to-
ward nucleophilic addition so that the allenic function may
not survive the reaction and/or purification conditions.1-4
Among the most commonly used methods is the reduction
of propargylic alcohols and esters to allenes. In another
method, the mild conditions of the reduction of propargylic
acetates into mono-, di-, and trisubstituted allenes by SmI2
in the presence of Pd0 opens the way to reactive allenes.5
For several reasons we became interested in pyridinic
allenes and in allenes containing electron attracting groups.
We found in the literature only one mention of an allenic
pyridine: 2,4-(4-pyridinyl)penta-2,3-diene prepared by re-
action of a Meldrum’s acid derivative with methyl-lithium
in THF-HMPA.6 5-(1,3-Butadienyl)-3-methyl-4-(1,2-pro-
RESULTS AND DISCUSSION
Propargyl alcohol 2 was prepared by the treating of
the lithium salt of phenylacetylene with pentafluorobenz-
aldehyde 1 in THF (yield 96%). This alcohol 2 was con-
verted to propargylic acetate 3 by acetic anhydride with a
catalytic amount of pyridine at reflux for 30 min. The re-
duction of propargylic acetate 3 with SmI2 in the presence
of catalytic Pd(0) yielded allene 4 (30%) and acetylene 5
(11%) (Scheme I). The 13C-NMR signal observed at d:
210.9 ppm in compound 4 is in agreement with the allenic
structure, whereas the 13C-NMR signals at d: 81.6 and 83.6
ppm for compound 5 are typical of acetylene. All others’
spectroscopic data confirm these structures.
3-(Trimethylsilyl)-1-(pyridine-3-yl)prop-2-yn-1-ol 7
* Corresponding author. E-mail: rerenler@gop.edu.tr, jfb@chem.sinica.edu.tw
† Present address: Department of Chemistry, Faculty of Art and Science, Gaziosmanpasa University, 60240 Tokat-Turkey

104 J. Chin. Chem. Soc., Vol. 54, No. 1, 2007
Erenler and Biellmann
Scheme I
was prepared by the treating of nicotinaldehyde 6 with
trimetylsilylacetylene and butyllithium in THF (yield 97%),
and its spectral data are consistent with those of the litera-
ture.8 Removal of the silyl group was performed with po-
tassium hydroxide in methanol to give propargylic alcohol
8. Sonogashira coupling of alkyne 8 with iodobenzene af-
forded the phenyl derivative of pyridine 9 converted to ace-
tate 10 with acetic anhydride in the presence of pyridine at
room temperature.9,10 Reduction of acetate 10 with SmI2 in
the presence of palladium afforded allene 11 (16%) and
acetylene 12 (40%). Moreover acetylene 12 was isomer-
ised with sodium ethoxide to allene 11 in a yield of 80%
(Scheme II). The signals in 1H-NMR spectrum at d: 6.57
and 6.64 ppm and in 13C-NMR at d: 208.1 ppm agree with
the allenic structure of compound 11.
The Pd-catalyzed cross-coupling reaction between
3-bromopyridine 13 with terminal alkyne 8 afforded dipyr-
idine 14. Treatment of this alcohol 14 with acetic anhydride
in the presence of pyridine gave the acetate 15. The treat-
ment of acetate 15 with SmI2 in the presence of palladium
Scheme II

Synthesis of Pentafluorophenyl- and Pyridinyl-3 Allenes
J. Chin. Chem. Soc., Vol. 54, No. 1, 2007 105
gave acetylene 16 and allene 17 (Scheme III). 1H and 13C-
NMR spectra of allene 17 agree with its symmetry. The sig-
nals at d: 6.64 ppm in the 1H-NMR spectrum and at d: 208.2
ppm in the 13C-NMR spectrum agree with the allenic struc-
ture for compound 17.
rected. 1H and 13C NMR spectra were recorded with Bruker
AMX400 and 500 MHz instruments. Chemical shifts are in
ppm from Me4Si, generated from the CDCl3. IR spectra
were taken with a Perkin-Elmer Paragon 1000 FT-IR spec-
trometer. Elemental analyses were measured with a Perkin-
Elmer 2400CHN instrument. Mass spectra were obtained
with a FAB JMS-700 double focusing mass spectrometer
(JEOL, Tokyo, Japan).
CONCLUSION
The allenes 4, 11 and 17 were prepared from the cor-
responding propargylic acetates by SmI2 reduction in the
presence of Pd(0). The acetylenes 5, 12 and 16 were also
produced. Acetylene 12 was isomerised to allene 11 by so-
dium ethoxide in THF. The allenes 4, 11 and 17 were stable
under the reaction conditions and could be chromatographed
without loss. So the prejudice regarding their instability is
not founded.
1-(Pentafluorophenyl)-3-phenylprop-2-yn-1-ol 2
To a solution of phenylacetylene (1.14 g) in anhy-
drous THF (10 mL) was added a solution of n-BuLi (7.0
mL) at -78 °C under argon. The reaction mixture was al-
lowed to warm to -50 °C, then a solution of pentafluoro-
benzaldehyde (2.0 g) in THF (5.0 mL) was slowly added
via syringe. After 1 h of stirring, the mixture was washed
with saturated NH4Cl, extracted with CH2Cl2 (2 × 10 mL),
dried over MgSO4, concentrated under vacuum to yield the
product as an oil (2.92 g, 96%). UV/Vis (CH2Cl2); lmax (e)
= 246 (17200); IR (CH2Cl2), u = 905, 997, 1118, 1502,
1653, 2228, 3055, 3571, 3675; 1H NMR (400 MHz, CDCl3),
d: 3.0 (brs, 1H), 5.98 (s, 1H), 7.29-7.37 (m, 3H), 7.42-7.45
(m, 2H); 13C NMR (100 MHz, CDCl3), d: 55.3, 85.4, 86.6,
114.7 (m), 121.5, 128.3 (2C), 129.1, 131.8 (2C), 136.4 (m),
138.9 (m), 140.0 (m), 142.5 (m), 143.4 (m), 145.9 (m); Ms
(FAB+), m/z, 299 [M+H]+; Anal. Calcd for C15H7F5O
(298.2), C 60.41; H 2.37. Found, C 60.52; H 2.31.
EXPERIMENTAL
General Procedures
Commercial reagents were purchased from standard
chemical suppliers and purified to match the reported phys-
ical and spectroscopic data. Solvents were purified and
dried by passing through activated aluminum oxide under
argon pressure. Flash column chromatography was carried
out on Silica Gel 60 (230-400 mesh, E. Merck). TLC was
performed on pre-coated glass plates of Silica Gel 60 F254
(0.25 mm, E. Merck); detection was done by spraying with
a solution of Ce(NH4)2(NO3)6, (NH4)6Mo7O24, and H2SO4
in water or ninhydrin and acetic acid solution in n-butanol
and subsequent heating on a hot plate. Melting points were
determined with a Büchi B-540 apparatus and are uncor-
1-(Pentafluorophenyl)-3-phenylprop-2-ynyl-1-acetate 3
A solution of 1-(pentafluorophenyl)-3-phenylprop-
2-yn-1-ol (1.0 g) in acetic anhydride (2 mL) and pyridine (2
drops) was heated at 80 °C for 30 min. After 30 min at rt,
the reaction mixture was quenched with water (10 mL), and
the product was extracted with CH2Cl2 (3 × 15 mL) and
Scheme III

106 J. Chin. Chem. Soc., Vol. 54, No. 1, 2007
Erenler and Biellmann
dried over MgSO4. After filtration and evaporation of the
solvent the crude material was chromatographed on silica
gel (hexane/EtOAc, 4/1) to give the acetate 3 as a solid
(0.93 g, 82%), mp 45-46 °C. UV/Vis (CH2Cl2), lmax (e) =
250 (30800); IR (CH2Cl2), u = 919, 997, 1126, 1214, 1370,
1426, 1440, 1508, 1652, 1749, 2233, 2857, 2953; 1H NMR
(400 MHz, CDCl3), d: 2.14 (s, 3H), 6.93 (s, 1H), 7.29-7.35
(m, 3H), 7.44-7.46 (m, 2H); 13C NMR (100 MHz, CDCl3),
d: 20.5, 55.9, 82.3, 87.0, 111.6 (m), 121.3, 128.3 (2C),
129.2, 131.9 (2C), 136.4 (m), 138.8 (m), 140.6 (m), 143.1
(m), 143.7 (m), 146.3 (m), 169.2; Ms (FAB+), m/z, 340
[M+H]+; Anal. Calcd for C17H9F5O2 (340.2), C 60.01; H
2.67. Found, C 60.11; H 2.59.
2-yn-1-ol 7 (1.30 g) in MeOH (5.0 mL) was added finely
powdered KOH (0.53 g) in methanol (3.0 mL). After the
completion of the reaction for 15 min at rt, the mixture was
acidified with 1.0 N HCl. The aqueous solution was sepa-
rated and neutralized with aqueous K2CO3 and extracted
with diethyl ether (3 ´ 10 mL). The combined organic ex-
tracts were dried (MgSO4), filtered and concentrated under
vacuum. The crude product was purified by column chro-
matography (silica, hexane/EtOAc, 1/1) to yield the prod-
uct 8 as an oil (0.48 g, 57%). UV/Vis (CHCl3), lmax (e) =
261 (2900); 1H NMR (500 MHz, CDCl3), d: 2.62 (d, J = 2.2
Hz, 1H), 5.47 (d, J = 2.2 Hz, 1H), 6.0 (brs, 1H), 7.23 (dd, J
= 7.8 Hz, J = 4.2 Hz, 1H), 7.87 (d, J = 7.8 Hz, 1H), 8.37 (d, J
= 4.2 Hz, 1H), 8.62 (s, 1H); 13C NMR (125 MHz, CDCl3),
d: 61.4, 74.9, 83.2, 123.6, 135.0, 136.9, 147.6, 148.4; IR
(CHCl3), u = 905, 1041, 1424, 1590, 2110, 2250, 3163; Ms
(FAB+), m/z, 134 [M+H]+ (100); HRMS (FAB+); Calcd for
C8H7NO: m/z 133.0528; Found m/z 133.0525.
Reduction of 1-(pentafluorophenyl)-3-phenylprop-2-
ynyl-1-acetate 3 with SmI2
To a solution of 1-(pentafluorophenyl)-3-phenyl-
prop-2-ynylacetate 3 (0.50 g) in THF (10 mL) was added
2-propanol (88 mg), tetrakis(triphenylphosphine)-palla-
dium(0) (84 mg) and 0.1 M solution of SmI2 in THF (36.8
mL). After completion of the reaction (2 h), water was
added (10 mL); the product was extracted with CH2Cl2 (2 ×
15 mL) and dried over MgSO4. After filtration and evapo-
ration of the solvent the crude material was chromato-
graphed on silica gel (hexane) to give the products 4 and 5:
1,2,3,4,5-pentafluoro-6-(3-phenylpropa-1,2-dienyl)-
benzene 4 as an oil (0.123 g, 30%), UV/Vis (CH2Cl2), lmax
(e) = 252 (28300); 1H NMR (400 MHz, CDCl3), d: 6.61 (s,
1H), 6.62 (s, 1H), 7.29 (m, 1H), 7.36 (m, 4H); 13C NMR
(100 MHz, CDCl3), d: 83.4, 97.8, 110.0 (m), 126.6 (m),
127.5 (2C), 127.9, 128.3 (m), 128.9 (2C), 129.7 (m), 132.5,
136.6 (m), 139.0 (m), 141.3 (m), 143.3 (m), 145.8 (m),
210.9; Ms (FAB+), m/z, 282 [M]+; Anal. Calcd for C15H7F5
(282.2), C 63.84; H 2.50. Found: C 63.79; H 2.55.
3-Phenyl-1-(pyridin-3-yl)prop-2-yn-1-ol 9
To a solution of 1-(pyridin-3-yl)prop-2-yn-1-ol 8
(1.20 g) and of iodobenzene (2.2 g) in THF (10.0 mL) was
added bis(triphenylphosphine)palladium chloride (0.126
g), copper(I)iodide (69 mg) and triethylamine (5.0 mL).
After being stirred for 15 h at rt, the reaction mixture was
neutralized with 2 M HCl and the product was extracted
with CH2Cl2 (2 ´ 10 mL). After adding NaHCO3 to the so-
lution, it was dried over MgSO4. After filtration and evapo-
ration of the solvent, the crude material was chromato-
graphed on silica gel (hexane/EtOAc, 3/2) to yield the
product 9 as an oil (1.50 g, 80%).11 UV/Vis (CHCl3), lmax
1
(e) = 244 (13700), 254 (13100); H NMR (400 MHz,
CDCl3), d: 5.27 (brs, 1H), 5.71 (s, 1H), 7.25-7.30 (m, 4H),
7.39 (dd, J = 1.5 Hz, J = 7.9 Hz, 2H), 7.95 (d, J = 7.9 Hz,
1H), 8.44 (s, 1H), 8.74 (s, 1H); 13C NMR (100 MHz,
CDCl3), d: 62.2, 86.7, 88.4, 122.1, 123.6, 128.3 (2C),
128.6, 131.7 (2C), 134.9, 137.3, 147.7, 148.6; IR (CHCl3),
u = 1040, 1432, 1485, 1737, 2232, 2359, 2394, 3014; Ms
(FAB+), m/z, 210 [M+H]+ (100), HRMS (FAB+); Calcd for
C14H11NO: m/z 209.0841; Found m/z 209.0845.
1,2,3,4,5-pentafluoro-6-(3-phenylprop-2-ynyl)ben-
zene 5 as a solid (45 mg, 11%). mp 56-57 °C; UV/Vis
1
(CH2Cl2), lmax (e) = 245 (11300); H NMR (400 MHz,
CDCl3), d: 3.84 (s, 2H), 7.28-7.31 (m, 3H), 7.32-7.41 (m,
2H); 13C NMR (100 MHz, CDCl3), d: 13.2, 81.6, 83.6,
110.9 (m), 122.9, 128.3 (3C), 131.8 (2C), 136.4 (m), 139.2
(m), 143.8 (m), 146.5 (m); IR (CH2Cl2), u = 901, 1002,
1125, 1509, 1658, 2303, 2362; Ms (FAB+), m/z, 282 [M]+;
Anal. Calcd for C15H7F5 (282.2), C 63.84; H 2.50. Found, C
63.86; H 2.46.
1-(3-Phenyl-1-(pyridin-3-yl)prop-2-ynyl)-1-acetate 10
To a solution of 3-phenyl-1-(pyridin-3-yl)prop-2-
yn-1-ol 9 (1.50 g) in acetic anhydride (3.0 mL) was added
four drops of pyridine. After completion of the reaction for
2 h at rt, the reaction mixture was washed with water (5.0
mL) and the product was extracted with CH2Cl2 (3 ´ 10
1-(Pyridin-3-yl)prop-2-yn-1-ol 8
A solution of 3-(trimethylsilyl)-1-(pyridin-3-yl)prop-

Synthesis of Pentafluorophenyl- and Pyridinyl-3 Allenes
J. Chin. Chem. Soc., Vol. 54, No. 1, 2007 107
mL) and dried over MgSO4. After filtration and evapora-
tion of the solvent, the crude material was chromato-
graphed on silica gel (hexane/EtOAc, 3/2) to give the prod-
uct 10 as an oil (1.30 g, 72%). UV/Vis (CHCl3) lmax (e) =
243 (15800); 1H NMR (500 MHz, CDCl3), d: 2.10 (s, 3H),
6.69 (s, 1H), 7.27 (m, 3H), 7.32 (dd, J = 4.0 Hz, J = 7.9 Hz,
1H), 7.44 (dd, J = 1.6 Hz, J = 7.9 Hz, 2H), 7.92 (d, J = 7.9
Hz, 1H), 8.60 (d, J = 4.0 Hz, 1H), 8.81 (s, 1H); 13C NMR
(125 MHz, CDCl3), d: 20.9, 63.9, 84.3, 87.8, 121.5, 123.7,
128.3 (2C), 129.1, 131.9 (2C), 133.3, 135.8, 148.7, 149.6,
169.6; IR (CHCl3), u = 1380, 1461, 1494, 1797, 1856,
1941, 2944, 3003, 3055; Ms (FAB+), m/z, 252 [M+H]+
(30), 235 (30), 221 (32), 119 (93); HRMS (FAB+) Calcd for
C16H13NO2: m/z 251.0946; Found m/z 251.0941.
Isomerisation of 3-(3-phenylprop-2-ynyl)pyridine 12
To a solution of 3-(3-phenylprop-2-ynyl)pyridine 12
(0.21 g) in THF (5.0 mL) was added sodium ethoxide (90
mg) in THF (3.0 mL). After completion of the reaction (4 h
at rt), water was added to the mixture; it was extracted with
CH2Cl2 (3 × 10 mL), dried over MgSO4, and concentrated
under vacuum to yield the product, 3-(3-phenylpropa-1,2-
dienyl)pyridine 11 (0.168 g, 80%).
1,3-Bis-pyridin-3-yl-prop-2-yn-1-ol 14
To a solution of 1-(pyridine-3-yl)prop-2-yn-1-ol 8
(1.56 g) in THF (10.0 mL) was added 3-bromopyridine 10
(2.0 g), bis(triphenylphosphine)palladium(II)dichloride
(164 mg), copper(I)iodide (89 mg) and triethylamine (4.0
mL). The mixture was stirred for 15 h at rt. The reaction
mixture was washed with water (5.0 mL), and the product
was extracted with dichloromethane (2 ´ 10 mL). The or-
ganic layer was dried over magnesium sulphate. After fil-
tration and evaporation of the solvent, the crude material
was chromatographed on silica gel (hexane/EtOAc, 3/2) to
yield the product 14 as an oil (0.51 g, 21%). UV/Vis
Reduction of propargylic acetate 10 with SmI2
To a solution of 3-phenyl-1-(pyridin-3-yl)prop-2-
ynyl acetate 10 (0.98 g) in THF (2.0 mL) was added 2-
propanol (0.23 g), Pd(PPh3)4 (0.23 g) and a 0.1 M solution
of SmI2 in THF (98 mL). After completion of the reaction
(10 h), the mixture was concentrated under vacuum. Water
was added to the reaction mixture; it was extracted with
CH2Cl2 (2 ´ 15 mL) and dried over MgSO4, After filtration
and evaporation of the solvent the crude material was
chromatographed on silica gel (hexane/EtOAc, 9/1) to give
the products 11 and 12.
1
(CH2Cl2), lmax (e) = 244 (23400); H NMR (400 MHz,
CDCl3), d: 5.50 (brs, 1H), 5.37 (s, 1H), 7.20 (dd, J = 4.9 Hz,
J = 7.9 Hz, 1H), 7.29 (dd, J = 4.9 Hz, J = 7.9 Hz, 1H), 7.69
(dt, J = 1.8 Hz, J = 3.7 Hz, J = 7.9 Hz, 1H), 7.94 (dd, J = 1.5
Hz, J = 7.9 Hz, 1H), 8.42 (d, J = 4.0 Hz, 1H), 8.48 (s, 1H),
8.66 (s, 1H), 8.77 (s, 1H); 13C NMR (100 MHz, CDCl3), d:
62.0, 82.8, 92.6, 119.7, 123.3, 123.6, 134.7, 136.9, 139.0,
147.8, 148.4, 148.8, 151.8; IR (CHCl3), u = 960, 1023,
1045, 1365, 1406, 1424, 1476, 1579, 1730, 2981, 3195;
HRMS (FAB+); Calcd for C13H10N2O: m/z 211.0871
[M+H]+; Found m/z 211.0871.
3-(3-phenylpropa-1,2-dienyl)pyridine 11 as an oil
(0.12 g, 16%). UV/Vis (CHCl3), lmax (e) = 250 (24800); 1H
NMR (400 MHz, CDCl3), d: 6.57 (d, J = 6.5 Hz, 1H), 6.64
(d, J = 6.5 Hz, 1H), 7.20-7.26 (m, 2H), 7.29-7.35 (m, 4H),
7.66 (d, J = 7.9 Hz, 1H), 8.45 (d, J = 4.3 Hz, 1H), 8.57 (s,
1H); 13C NMR (100 MHz, CDCl3), d: 95.2, 99.0, 123.6,
127.0 (2C), 127.6, 128.9 (2C), 129.7, 132.8, 133.7, 148.2,
148.3, 208.1; IR (CHCl3), u = 905, 1023, 1214, 1421, 1520,
1601, 1941, 2398, 3025, 3623, 3690; HRMS (FAB+); Calcd
for C14H12N: m/z 194.0970; Found m/z 194.0967.
1,3-Bis-pyridin-3-yl-prop-2-ynyl-1-acetate 15
To a solution of alcohol 14 (0.31 g) in acetic anhy-
dride (3.0 mL) was added 5 drops of pyridine. After 3 h at
rt, the reaction mixture was washed with water (5.0 mL)
and the product was extracted with dichloromethane (3 ´
10 mL); it was then dried over magnesium sulfate. After fil-
tration and evaporation of the solvent the crude material
was chromatographed on silica gel (hexane/EtOAc, 1/4) to
yield the product 15 as an oil (0.27 g, 73%). UV/Vis
3-(3-phenylprop-2-ynyl)pyridine 12 as an oil (0.30 g,
40%). UV/Vis (CH2Cl2), lmax (e) = 240 (17500); 1H NMR
(500 MHz, CDCl3), d: 3.79 (s, 2H), 7.23 (dd, J = 4.3 Hz, J =
7.8 Hz, 1H), 7.27 (m, 3H), 7.42 (m, 2H), 7.71 (d, J = 7.8 Hz,
1H), 8.48 (d, J = 4.3 Hz, 1H), 8.62 (s, 1H); 13C NMR (125
MHz, CDCl3), d: 23.2, 83.3, 85.9, 123.2, 123.4, 128.1,
128.3 (2C), 131.6 (2C), 132.4, 135.5, 148.1, 149.3; IR
(C2Cl2), u = 1026, 1166, 1214, 1295, 1421, 1487, 1579, 1601,
2302, 3040, 3682; HRMS (FAB+); Calcd for C14H12N: m/z
194.0970; Found m/z 194.0975.
1
(CHCl3), lmax (e) = 243 (14700); H NMR (400 MHz,
CDCl3), d: 2.11 (s, 3H), 6.67 (s, 1H), 7.23 (dd, J = 4.9 Hz, J
= 7.7 Hz, 1H), 7.32 (dd, J = 4.9 Hz, J = 7.7 Hz, 1H), 7.73 (d,
J = 7.9 Hz, 1H), 7.88 (d, J = 7.9 Hz, 1H), 8.53 (s, 1H), 8.60

108 J. Chin. Chem. Soc., Vol. 54, No. 1, 2007
Erenler and Biellmann
(s, 1H), 8.67 (s, 1H), 8.80 (s, 1H); 13C NMR (100 MHz,
CDCl3), d: 20.8, 63.7, 84.3, 87.8, 118.8, 122.9, 123.6, 132.6,
135.3, 138.8, 149.0, 149.3, 150.1, 152.4, 169.4; IR (CHCl3),
u = 1406, 1432, 1476, 1517, 1576, 1738, 2250, 2398, 2974;
Ms (FAB), m/z (%) = 253 [M+H]+ (60), 193 (30), 143 (35),
119 (85); HRMS (FAB+); Calcd for C15H12N2O2: m/z
252.2680; Found m/z 252.2684.
1421, 1472, 1520, 1605, 1793, 1944, 2250, 2391, 3151;
HRMS (FAB+); Calcd for C13H10N2: m/z 195.0922 [M+H]+;
Found m/z 195.0923.
Received April 6, 2006.
Reduction of propargylic acetate 15 with SmI2
REFERENCES
To a solution of acetate 15 (0.26 g) in THF (2.0 mL)
was added 2-propanol (62 mg), Pd(PPh3)4 (60 mg) and a 0.1
M SmI2 solution in THF (25.8 mL). After completion of the
reaction for 4 h, half of the solvent was evaporated. Water
(8 mL) was added to the mixture and it was extracted with
dichloromethane (2 ´ 15 mL). The organic layer was dried
over magnesium sulfate and treated with silica gel chroma-
tography (hexane/EtOAc, 1/4) to give products 16 and 17:
3-(3-(pyridine-3-yl)prop-2-ynyl)pyridine 16 as an oil
(51 mg, 20%), UV/Vis (CHCl3), lmax (e) = 242 (22900); 1H
NMR (400 MHz, CDCl3), d: 3.86 (s, 2H), 7.24 (dd, J = 4.9
Hz, J = 7.9 Hz, 1H), 7.31 (dd, J = 5.2 Hz, J = 7.6 Hz, 1H),
7.70 (dt, J = 1.8 Hz, J = 7.8 Hz, 1H), 7.77 (d, J = 7.8 Hz,
1H), 8.53 (s, 2H), 8.68 (s, 2H); 13C NMR (100 MHz, CDCl3),
d: 23.3, 80.0, 89.5, 122.9, 135.8, 138.6 (2C), 147.9, 148.4
(2C), 149.0, 152.3 (2C); IR (CHCl3), u = 1096, 1380, 1421,
1476, 1520, 1598, 1797, 2243, 2405; HRMS (FAB+); Calcd
for C13H10N2: m/z 194.0884 [M]+; Found m/z 194.08473.
3-(3-(pyridine-3yl)propa-1,2-dienyl)pyridine 17 as
an oil (59 mg, 23%) UV/Vis (CH2Cl2), lmax (e) = 251
(22100); 1H NMR (400 MHz, CDCl3), d: 6.64 (s, 2H), 7.25
(dd, J = 4.8 Hz, J = 7.9 Hz, 2H), 7.64 (dd, J = 1.7 Hz, J = 7.9
Hz, 2H), 8.47 (dd, J = 1.4 Hz, J = 4.8 Hz, 2H), 8.56 (s, 2H);
13C NMR (100 MHz, CDCl3), d: 95.8, 123.7, 129.0, 133.8,
148.3, 148.6, 208.3; IR (CHCl3), u = 1026, 1093, 1376,
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11. Data close to those published.10