Free radical cyclization of 1,3-dicarbonyl compounds mediated by manganese(III) acetate with alkynes and synthesis of tetrahydrobenzofurans, naphthalene, and trifluoroacetyl substituted aromatic compounds

Article abstract of DOI:10.1080/00397910500501516

Furan derivatives were obtained from radical cyclizations of 1,3-dicarbonyl compounds mediated by Mn(OAc)₃ with phenyl acetylene 2a (14-66% yields). Naphthalene derivates 4a and 4b were produced in the treatments with 2a. In addition to these,

Full text of DOI:10.1080/00397910500501516

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Free Radical Cyclization of 1,3‐Dicarbonyl
Compounds Mediated by Manganese(III)
Acetate with Alkynes and Synthesis of
Tetrahydrobenzofurans, Naphthalene,
and Trifluoroacetyl Substituted Aromatic
Compounds
Oguzhan Alagoz a , Mehmet Yılmaz a & A. Tarık Pekel a
a Department of Chemistry, Ankara University, Tandogan, Ankara, Turkey
Published online: 16 Aug 2006.
To cite this article: Oguzhan Alagoz , Mehmet Ylmaz & A. Tark Pekel (2006) Free Radical Cyclization
of 1,3‐Dicarbonyl Compounds Mediated by Manganese(III) Acetate with Alkynes and Synthesis of
Tetrahydrobenzofurans, Naphthalene, and Trifluoroacetyl Substituted Aromatic Compounds, Synthetic
Communications: An International Journal for Rapid Communication of Synthetic Organic Chemistry, 36:8,
1005-1013, DOI: 10.1080/00397910500501516
To link to this article: http://dx.doi.org/10.1080/00397910500501516
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Synthetic Communicationsw, 36: 1005–1013, 2006
Copyright # Taylor & Francis Group, LLC
ISSN 0039-7911 print/1532-2432 online
DOI: 10.1080/00397910500501516
Free Radical Cyclization of 1,3-Dicarbonyl
Compounds Mediated by Manganese(III)
Acetate with Alkynes and Synthesis
of Tetrahydrobenzofurans, Naphthalene,
and Trifluoroacetyl Substituted
Aromatic Compounds
Oguzhan Alagoz, Mehmet Yılmaz, and A. Tarık Pekel
Department of Chemistry, Ankara University, Tandogan, Ankara, Turkey
Abstract: Furan derivatives were obtained from radical cyclizations of 1,3-dicarbonyl
compounds mediated by Mn(OAc)3 with phenyl acetylene 2a (14–66% yields).
Naphthalene derivates 4a and 4b were produced in the treatments with 2a. In
addition to these, trifluoroacetyl substituted naphthalene 4c, benzofuran 4d, and ben-
zothien 4e were obtained in the reactions of trifluoromethyl-1,3-dicarbonyls (1 g–i)
with 2a.
Keywords: Benzofuran, benzothien, 1,3-dicarbonyl, free radical cyclization, furan,
manganese(III) acetate, naphthalene, trifluoroacetyl
It is widely known that the C–C bond is obtained by transition metal salts–
mediated oxidative addition of organic compounds to unsaturated
systems.[1] Mn(OAc)3 is used effectively as a mediator in the inter- and intra-
molecular cyclizations for the synthesis of furans,[2–6] dihydrofurans,[7–9]
lactones,[4] and natural products.[10–13] The addition of a-carbon radical
generated in carbonyl compounds using Mn(OAc)3 and cerium(IV) amon-
niumnitrate (CAN) to aromatics was first reported by Heiba et al.[14] Malony-
lation and nitromethylation of aromatic compounds are also known.[15–17]
Received in the U.K. February 3, 2005
Address correspondence to Mehmet Yılmaz, Science Faculty, Department of
Chemistry, Ankara University, Tandogan 06100,
meyilmaz@science.ankara.edu.tr
Ankara, Turkey. E-mail:
1005

1006
O. Alagoz, M. Yılmaz, and A. T. Pekel
Many furans show biological activities, and furan derivatives are useful
synthetic intermediates used in the synthesis of photochromic molecules,
food additives, and pharmaceuticals.[18–20] Additionally, fluorinated
molecules are widespread in pharmaceutical applications such as proteaz
and phosphodiestereaz inhibitors, antiparasitic agents, anticancer compunds,
antibacterials, and anastetics.[21,22] Here we studied Mn(OAc)3-mediated
addition of various 1,3-dicarbonyl compounds to alkynes and obtained
furan, tetrahydrobenzofurans, naphthalens, and trifluoroacetyl substituted
aromatic compounds, which are worth consideration.
We report a one-step synthesis of tetrahydrobenzofuran, naphthalens, and
trifluoroacetyl substituted organic compounds by Mn(OAc)3-mediated radical
cyclization of 1,3-dicarbonyls (1a–i) with 2a and 2b (molar ratio 2 : 3 : 1,
respectively). The best product yields were obtained at 80 8C in HOAc.
After workup, all new products purified with preparative TLC were character-
1
ized by IR; H, 19F, and 13C NMR; MS; and microanalysis, and the other
1
products were characterized by H NMR. All spectroscopic data are given
in the experimental section.
In the radical cyclization, 1,3-dicarbonyls without aromatic groups
(1a–d) and 1,3-dicarbonyls (1e–i) containing aromatic groups such as
phenyl, 2-furyl, and 2-thienyl were used. Furan and tetrahydrobenzofurans
were obtained in the Mn(OAc)3-mediated treatments of 1a–d with 2a and
2b. Recommended reaction mechanism is given in Scheme 1, and the
results of the experiment are given in Table 1.
According to this mechanism, Mn(OAc)3 with the enole forms of 1,3-
dicarbonyls (1a–d) forms Mn(III)-enolate complex A. In this structure,
Mnþ3 is reduced to Mnþ2 and an oxo radical B forms. Oxo radical changes
into a-carbon radical, which is more stable, and this radical is added to
Scheme 1.

Cyclization of 1,3-Dicarbonyl Compounds
1007
Table 1. Synthesis of furan and benzofuran derivatives
Product and
yield (%)a
Entry
1,3-Dicarbonyl
R1
R2
Alkyne
1
2
3
4
5
1a
1b
1b
1c
1d
Me
OEt
2a
2a
2b
2b
2b
3a (14)
3b (66)
3c (50)
3d (38)
3e (60)
–CH2CH2CH2–
–CH2CH2CH2–
–CH2CHPhCH2–
–CH2C(CH3)2CH2–
aYield of isolated product based on the alkynes.
alkyne (2a, 2b), so C intermediate product gains. This intermediate product is
oxidized to carbocation D with the equivalent Mn(OAc)3, and furan deriv-
atives E (3a–d) form intramolecular cyclization of oxanion.
We obtained 3a[23–25] (14%) in the treatment of 1a with 2a with moderate
yield, and the radical cyclization of 1b with 2a and 2b gave tetrahydrobenzo-
furans 3b[26] (66%) and 3c (50%), respectively. Additionally, the reaction of
1d with 2b gave 3e (60%) with a better yield. Because 2b is more sterically
hindered than 2a, the reaction of 1b with 2b formed tetrahydrobenzofuran
with lower yields than that of 2a (entries 2, 3).
In the Mn(OAc)3-mediated radical cyclizations of 1,3-dicarbonyl
compounds (1e–i) containing aromatic groups with 2a, we obtained benzo-
furan, benzothien, and naphthalene derivatives. The recommended reaction
mechanism for formation of these compounds is given in Scheme 2 and the
results of experiment are given in Table 2.
Intermediate product F, which is formed by the addition of a-carbon
radical generated by 1,3-dicarbonyl compounds containing aromatic group
Scheme 2.

1008
O. Alagoz, M. Yılmaz, and A. T. Pekel
Table 2. Synthesis of benzothien, benzofuran, and naphthalene derivatives
Product and
yield (%)a
Entry
1,3-Dicarbonyl
X
R1
1
2
3
4
5
1e
1f
–CH55CH–
–CH55CH–
–CH55CH–
Me
Ph
4a (44)
4b (30)
4c (42)
4d (38)
4e (45)
1g
1h
1i
CF3
CF3
CF3
O
S
aYield of isolated product based on the alkynes.
(1e–i) mediated Mn(OAc)3 to 2a, can follow two ways. First, H, which is
formed by the addition of the radical to aromatic group as electrophilic
radical, produces carbocation intermediate product I by oxidizing the equival-
ent Mn(OAc)3. J (4a–e) compounds are formed by removing a Hþ from this
structure. Second, F is oxidized to carbocation G by the equivalent Mn(OAc)3
directly, and this intermediate product can form I following path i or furans K
following path ii. Yet, furans were not formed in the treatments of 1e–i with
2a in our study. For this reason we believe that this mechanism forms 4a–e
compounds following the first way.
Although 4a[27,28] was obtained with 44% yield, in the reaction of 1e with
2a, the treatment of 1f with 2a gave naphthalene derivative 4b[28] with a lower
yield (30%). Trifluoroacetyl substituted naphthalene (4c, 42%), benzofuran
(4d, 38%), and benzothien (4e, 45%) compounds were obtained in the treat-
ments of trifluoromethyl-1,3-dicarbonyls containing different aromatic
groups (1g–i) with 2a. Unknown products formed in the treatments of 1e–i
with 2b.
Compounds 4a–c were characterized by spectroscopic techniques and
1
microanalysis. The characteristic coupling of these compounds in H, 13C,
and 19F NMR spectra are given later. The peaks at 12–14 ppm (s, -OH) in
1H NMR spectra of 4a–e disappeared during D2O exchanges. Although
H-5 protons of 4a and 4b appear as a singlet, the protons H-3 of 4c and H-5
of 4d and 4e appear as quartet (4JH-F ¼ 2 Hz) because of the coupling with
CF3. Similarly, the peak of –CF3 in 19F NMR spectra of 4c–e resonated as
a doublet (4JF-H ¼ 2 Hz). The chemical shift values of carbonyl groups at
4a and 4b in 13C NMR spectra were 205 ppm (s), and 202 ppm (s), respect-
ively. Additionally, these values of the carbonyl groups at 4c–e were
185–189 ppm quartet (2JC-F ¼ 35 Hz).
EXPERIMENTAL
Melting points were determined on Gallencamp capillary melting-point
apparatus. IR spectra (KBr disc, CHCl3) were obtained with a Matson 1000

Cyclization of 1,3-Dicarbonyl Compounds
1009
1
FT-IR in the 400–4000 cm21 range with 4 cm21 resolution. H (400 MHz),
19F (376 MHz), and 13C NMR (100 MHz) spectra were recorded on a
Bruker DPX 400-MHz high-performance digital FT-NMR, in CDCl3
solution using TMS as internal standard. The electron impact mass spectra
(EIMS 70 eV) were measured on Shimadzu GC-17A/GC-MS-QP5000
spectrophotometer. Microanalyses were performed on a Leco 932 CHNS-O
instrument.
Manganese(III) acetate dihydrate (98%) was prepared by an electroche-
mical method according to the literature.[29] All the alkynes and trifluoro-
methyl-1,3-dicarbonyl compounds were purchased from ABCR; the other
1,3-dicarbonyl compounds and preparative silica gel (PF 254–366 nm) were
purchased from Merck.
General Procedure
A solution of manganese(III) acetate (6 mmol, 1.61g) in 30mL of glacial acetic
acid was heated under nitrogen atmosphere at 808C until it dissolved. After
Mn(OAc)3 was dissolved completely, the solution was cooled down to 508C.
A solution of 1,3-dicarbonyl compound (4mmol) and alkyne (2 mmol) in
5 mL of acetic acid was added to this mixture. The reaction finished when the
dark brown color of the solution disappeared. Acetic acid was evaporated out
under reduced pressure. Water was added to the residue and extraction was
performed with CHCl3 or EtOAc (3 ꢀ 20mL). The combined organic
extracts were neutralized with satd. NaHCO3 solution, dried over anhydrous
Na2SO4, and evaporated. The residue was purified by TLC (silica gel PF
254–366 nm) eluting with hexane–EtOAc (4 : 1).
1
2-Methyl-5-phenyl-furan-3-carboxylicacid ethylester (3a): yellow oil; H
NMR, d (ppm): 1.39 (t, 3H, J ¼ 7.1 Hz), 2.67 (s, 3H), 4.34 (q, 2H,
J ¼ 7.1 Hz), 6.91 (s, 1H), 7.28 (tt, 1H, J ¼ 7.4 and 1.2 Hz), 7.40 (td, 2H,
J ¼ 7.4 and 1.5 Hz), 7.66 (dd, 2H, J ¼ 8.3 and 1.2 Hz).
2-Phenyl-6,7-dihydro-5H-benzofuran-4-one (3b): colorless solid, mp 135–
136 8C; IR, ymax: 3080–3050, 2970, 1675 (C55O), 1600, 1450–1380,
1
1130 cm21; H NMR, d (ppm): 2.23 (m, 2H), 2.56 (t, 2H, J ¼ 6.4 Hz), 2.98
(t, 2H, J ¼ 6.3 Hz), 6.91 (s, 1H), 7.31 (t, 1H, J ¼ 7.5 Hz), 7.41 (t, 2H,
J ¼ 7.5 Hz), 7.67 (d, 2H, J ¼ 7.5 Hz); 13C NMR, d (ppm): 22.9, 23.8, 38.0,
101.2, 123.3, 124.3, 128.4, 129.2, 130.2, 154.6, 167.1, 194.9 (C55O); MS
(m/z, %): 213 (Mþ1, 0.2), 212 (Mþ, 2.71), 104 (COC6Hþ5 , 19.98), 76
(C6Hþ5 , 28.87), 50 (100), 41 (68.86); anal. calcd. for C14H12O2: C, 79.24; H,
5.66; found: C, 79.30; H, 5.68.
3-Ethyl-2-phenyl-6,7-dihydro-5H-benzofuran-4-one (3c): colorless solid,
mp 88–90 8C IR, ymax: 3050, 2980, 1685 (C55O), 1450, 1070–1020 cm21
;

1010
O. Alagoz, M. Yılmaz, and A. T. Pekel
1H NMR, d (ppm): 1.30 (t, 3H, J ¼ 7.4 Hz), 2.21 (m, 2H), 2.53 (t, 2H,
J ¼ 6.5 Hz), 2.90 (m, 4H), 7.33 (tt, 1H, J ¼ 7.4 and 1.7 Hz), 7.45 (td, 2H,
J ¼ 7.5 and 1.7 Hz), 7.61 (dd, 2H, J ¼ 7.5 and 1.4 Hz); 13C NMR, d (ppm):
14.9, 18.1, 22.9, 24.0, 30.1, 38.9, 121.8, 121.9, 126.3, 127.9, 129.0, 131.0,
148.9, 166.7, 195.7 (C55O); MS, (m/z, %): 241 (MHþ, 9.67), 240 (Mþ,
68.02), 225 (Mþ–CH3, 8.14), 105 (C6H5COþ, 31.69), 77 (C6Hþ5 , 100.00),
41.08 (52.62); Anal. calcd. for C16H16O2: C, 79.97; H, 6,71; found: C,
79.94; H, 6.74.
3-Ethyl-2,6-diphenyl-6,7-dihydro-5H-benzofuran-4-one(3d):colorlesssolid,
mp 138–139 8C; IR, ymax
:
3000, 2980, 1685 (C55O), 1450,
1060cm21; H NMR, d (ppm): 1.33 (t, 3H, J ¼ 7.4 Hz), 2.80 (m, 2H), 2.94
(q, 2H, J ¼ 7.4 Hz), 3.12 (dd, 1H, J ¼ 17.1 and 11.1Hz), 3.24 (dd, 1H,
J ¼ 17.1 and 5.3 Hz), 3.62 (m, 1H), 7.40–7.50 (m, 8H, arom.), 7.62 (dd, 2H,
J ¼ 7.9 and 1.3 Hz); 13C NMR, d (ppm): 14.9, 18.1, 31.8, 41.6, 46.2, 121.8,
126.4, 127.2, 127.6, 128.1, 129.1, 129.3, 130.9, 143.0, 149.5, 165.9, 194.2
(C55O); MS, (m/z, %): 317 (MHþ, 2.35), 316 (Mþ, 11.04), 211 (Mþ-
C6H5CO, 6.98), 183 (Mþ–C6H5CO –C2H5, 12.66), 105 (C6H5COþ, 27.60),
102 (89.61), 77 (C6Hþ5 , 100.00); anal. calcd. for C22H20O2: C, 83.54; H, 6.33;
found: C, 83.62; H, 6.36.
1
3-Ethyl-6,6-dimethyl-2-phenyl-6,7-dihydro-5H-benzofuran-4-one (3e):
pale yellow oil; IR, ymax: 3050, 2980, 1685 (C55O), 1450, 1070–1020cm21
;
1HNMR, d (ppm): 1.18 (s, 6H, -CH3), 1.29 (t, 3H, J ¼ 7.4 Hz, -CH3), 2.41
(s, 2H), 2.79 (s, 2H), 2.89 (q, 2H, J ¼ 7.4 Hz, -CH2), 7.33 (t, 1H,
J ¼ 7.3 Hz), 7.44 (t, 2H, J ¼ 7.6 Hz), 7.6 (dd, 2H, J ¼ 7.7 and 1.1 Hz); 13C
NMR, d (ppm): 14.9, 18.0, 26.8, 29.0, 35.5, 38.3, 53.1, 121.6, 126.2, 127.4,
129.0, 130.5, 134.0, 149.3, 166.1, 195.5 (C55O); MS, (m/z, %): 269 (MHþ,
1.06), 268 (Mþ, 4.92), 165 (Mþ-2CH3 –C6H5, 1.68), 152 (Mþ–3CH3
–
C6H5, 1.25), 104 (COC6Hþ5 , 17.97), 77 (C6Hþ5 , 54.11), 41 (100.00); anal.
calcd. for C18H20O2: C, 80.56; H, 7.51; found: C, 80.51; H, 7.48.
1-(1-Hydroxy-4-phenyl-naphthalen-2-yl)-ethanone (4a): pale yellow solid,
mp: 181–182 8C; IR, ymax: 3020, 1635 (C55O), 1600, 1500, 1450–1400,
1250cm21 1H NMR, d (ppm): 2.73 (s, 3H, -CH3), 7.45 (m, 5H), 7.55
;
(m, 3H), 7.78 (dd, 1H, J ¼ 7.7 and 1.7 Hz), 8.57 (dd, 1H, J ¼ 7.6 and
1.7 Hz), 13.98 (s, 1H, -OH); 13C NMR, d (ppm): 27.8, 113.6, 125.6, 126.2,
126.4, 126.7, 128.2, 129.3, 130.7, 131.0, 131.8, 136.7, 140.9, 162.7, 205.3
(C55O); MS, (m/z, %): 263 (MHþ, 17.89), 262 (Mþ, 100.00), 247 (Mþ
–
CH3, 63.60), 220 (Mþ –CH3CO, 1.94), 202 (Mþ –OH –CH3CO, 5.20), 189
(32.64), 186 (Mþ –C6H5, 7.64), 77 (C6H5þ, 2.56), 43 (CH3COþ, 100.00);
anal. calcd. for C18H14O2: C, 82.42; H, 5.38; found: C, 82.34; H, 5.41.
(1-Hydroxy-4-phenyl-naphthalen-2-yl)-phenyl-methanone (4b): yellow
solid, mp 159–160 8C; IR, ymax: 3030, 1615 (C55O), 1600, 1500,

Cyclization of 1,3-Dicarbonyl Compounds
1011
1
1450–1380, 1250 cm21; H NMR, d (ppm): 7.42–7.62 (m, 11H), 7.76 (dd,
2H, J ¼ 7.6 and 1.6 Hz), 7.85 (dd, 1H, J ¼ 7.1 and 2.5 Hz), 8.65 (dd, 1H,
J ¼ 7.2 and 2.6 Hz), 13.98 (s, 1H, –OH); 13C NMR, d (ppm): 113.0, 125.6,
126.4, 126.8, 128.1, 128.1, 128.6, 129.3, 129.3, 129.6, 129.9, 131.0, 131.3,
131.4, 132.6, 136.6, 139.0, 140.8, 164.2, 202.4 (C55O); MS, (m/z, %): 325
(MHþ, 2.82), 324 (Mþ, 18.83), 246 (Mþ -C6H5, 4.90), 218 (Mþ -COC6H5,
1.91), 189 (22.22), 105 (COC6H5þ, 46.91), 77 (C6H5þ, 100.00); anal. calcd.
for C23H16O2: C, 85.16; H, 4.97; found: C, 85.09; H, 5.04.
2,2,2-Trifluoro-1-(1-hydroxy-4-phenyl-naphthalen-2-yl)-ethanone (4c): pale
1
yellow solid, mp 92–93 8C; H NMR, d (ppm): 7.49 (m, 5H), 7.61 (m, 2H),
7.68 (td, 1H, J ¼ 7.6 and 1.8 Hz), 7.81 (dd, 1H, J ¼ 7.2 and 1.1 Hz), 8.59 (dd,
1H, J ¼ 8.4 and 1.1Hz), 12.90 (s, 1H, –OH); 13C NMR, d (ppm): 107.94,
1
117.12 (q, JC-F ¼ 289 Hz), 123.53, 125.20, 125.35, 126.50, 126.86, 127.96,
2
128.81, 130.27, 132.21, 132.65, 137.02, 139.45, 165.96, 184.23 (q, JC-
5
¼ 35.5 Hz); 19F NMR, d (ppm): 269.6 (d, JF-H ¼ 2 Hz, –CF3); MS, (m/z,
F
%): 317 (MHþ, 13.31), 316 (Mþ, 72.78), 246 (Mþ –CF3, 85.39), 219 (Mþ
–
COCF3, 8.28), 189 (60.00), 105 (C6H5COþ, 12.09), 94 (C6H5OHþ, 100.00),
77 (C6Hþ5 , 12.15), 69.05 (CF3þ, 29.07), 43 (CH3COþ, 33.67); anal. calcd. for
C18H11F3O2: C, 68.36; H, 3.51; found: C, 68.40; H, 3.44.
2,2,2-Trifluoro-1-(4-hydroxy-7-phenyl-benzofuran-5-yl)-ethanone (4d): pale
yellow solid, mp: 103–104 8C; IR, ymax: 3030, 1615 (C55O), 1600, 1250, 750,
703 cm21; 1HNMR, d (ppm): 7.00 (d, 1H, J ¼ 2.0 Hz), 7.44 (tt, 1H, J ¼ 7.1 and
5
1.4 Hz), 7.52 (m, 4H), 7.68 (q, 1H, JH-F ¼ 2.1 Hz, H-5), 7.93 (d, 1H,
1
J ¼ 2.0 Hz), 11.78 (s, 1H); 13C NMR, d (ppm): 107.6, 110.3, 116.6 (q, JC-
4
¼ 289.8 Hz, CF3), 123.21 (q, JC-F ¼ 3.7 Hz, C-5), 127.0, 127.9, 128.2,
F
135.9, 139.2, 128.8, 150.3, 184.5 (d, JC-F ¼ 35.9Hz, C55O); 19F NMR, d
2
(ppm): 269.7 (d, JF-H ¼ 2.2 Hz, –CF3); MS, (m/z, %): 307 (MHþ, 7.23),
5
306 (Mþ, 45.76), 237 (Mþ -CF3, 100.00), 209 (Mþ -COCF3, 6.66), 118 (Mþ
–OH –COCF3 -C6H5, 37.40), 97 (COCFþ3 , 4.14), 77 (C6H5þ, 21.09), 69 (CFþ3 ,
7.57); anal. calcd. for C16H9F3O3: C, 62.75; H, 2.96; found: C, 62.81; H, 2.88.
2,2,2-Trifluoro-1-(4-hydroxy-7-phenyl-benzo[b]thiophen-5-yl)-ethanone
(4e): yellow solid, mp 102–103 8C; IR, ymax: 3030, 1600 (C55O), 1600, 1250,
745, 700 cm21; 1H NMR, d (ppm): 7.51 (m, 2H), 7.54 (m, 4H), 7.71 (q, 1H,
5JH-F ¼ 2.2 Hz, H-5), 7.86 (d, 1H, J ¼ 5.4 Hz), 12.13 (s, 1H, –OH); 13C
1
NMR, d (ppm): 109.3, 117.5 (q, JC-F ¼ 289.5 Hz, –CF3), 125.4, 126.4
4
(q, JC-F ¼ 3.8 Hz, C-5), 128.7, 129.6, 129.8, 131.4, 135.4, 140.1, 147.3,
2
161.6, 185.1 (q, JC-F ¼35.5 Hz, C55O); 19F NMR, d (ppm): 270.51
5
(d, JF-H ¼ 2.0 Hz, –CF3); MS, (m/z, %): 323 (MHþ, 18.36), 322 (Mþ,
100.00), 303 (Mþ –H2O, 1.99), 253 (Mþ –CF3, 99.42), 225 (Mþ –COCF3,
3.61), 195 (42.30), 152 (19.58), 97 (COCFþ3 , 39.21), 77 (C6H5þ, 5.59), 69
(CFþ3 , 12.10); anal. calcd. for C16H9F3O2S: C, 59.63; H, 2.81; S, 9.95;
found: C, 59.67; H, 2.88; S, 9.87.

1012
O. Alagoz, M. Yılmaz, and A. T. Pekel
ACKNOWLEDGMENT
This study was financially supported by the Scientific and Technical Research
Council of Turkey (TBAG-AY/268 coded project). EIMS analyses were
performed at Scientific Research Center of Ankara University.
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